# Feed wire sizing to my garage



## magu

Hi all, I'm looking for some advice. I'm looking to add power to my detached garage so I can run my machines and do a bit of tinkering. My question is what size wire I need, the run will be 70', it will power some lights (>2amps), a little old radio, and 1 thing at a time (it's just me, I can't weld, run a mill and a sander all at once). I will be installing a 1 HP vfd to power both my mill and lathe (240 3ph, 3/4 and 1/2 Hp respectively) I will also install 8 outlets. 

Can I use 12/3g wire for this? 

My plan would be to put half the lights and half the outlets on each circuit breaker, that way if I blow a breaker I won't lose all my lighting. I would then use both legs to feed my vfd as well.


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## uncle harry

Hi,   Wire size might depend on the potential of additional needs such as an air compressor or any other needs or bargains that may come along in the future.  I supplied my outbuildings with # 6 direct burial thinking that 60 amps continuous would all that I would need.  Now I wish it was at least # 4.


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## ddickey

I used 6 gauge also.


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## cathead

You only want to bury the wire once.  I put in a 100 amp service and have no regrets.  Wire is cheap compared
to the time and expense of digging in another line.  Also a breaker box is necessary so 
you can have various breakered lines to your equipment.


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## roadie33

I used 3/0 for a 200 AMP Breaker box for my garage.
Never know when you might have the lights on, AC, air compressor and welder running at the same time.
Better to have more than needed than not enough and blow breakers all the time.


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## jim18655

Are you using direct bury cable or conduit? You could save on the expense now by installing a large (2") PVC conduit and up-size the wire later. It's more expensive overall but might help you out now.  I wouldn't do less than 100 amps for the equipment you listed. The welder might have substantial draw and don't forget about running some type of heat in the winter.


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## Silverbullet

I wouldn't go with anything smaller then #6 for the distance at least . If you have to dig conduits nice but 2" black water pipe will work and 100' roll is pretty cheap . You should bury at minimum 18" , 36" would be better the straighter the run the better . You can tie string to a dense sponge and blow the line thru with a air tank or compressor. If you pull the wire add an extra string in case you need to had later lines. Be careful to keep the buried line safe from any digging. If you use #4 you should have plenty of current with no worries of melting and shorts. Wires get hot when there's to much draw.  Temco a store on eBay has pretty good prices Ck them out . Good luck and keep safe


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## magu

Thank you all for your replies, at the moment, I have 1/2" EMT running to the garage with 5 very old and crusty wires in it. I can either make use of that, or wait for a year or two, but an eventual new trench for bigger wires is very low on the family centric priority list. Hence my attempt to use 12g copper. 

I'm nearly never out there before the baby is asleep, the housework, the leftover office work is done, and the clock has struck midnight. As a result, in the short term at least, AC will be unnecessary, and an air compressor would not be well received by the neighbors.


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## markba633csi

If it was only 50 feet I'd say 10 gauge but I think you should use at least 8, maybe 6.  70 feet of 12 gauge will not be good enough at all if you want to weld.
Mark S.


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## jim18655

Black water pipe isn't code compliant. I'd hate to see you get shot down by a building inspector, assuming you'd need an inspection in your area. I know in some places you can't plant a flower without someone sticking their nose in your business.


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## Glenn Brooks

What Jim said.  Check your local electrical code.  Most all local codes are based on the national electric code. So mostly everywhere is similar.  It will tell you what depth to bury, wire size for amperage, etc. 

I just did what you contemplate and dug  a 36" deep  trench 100' in two days with a rented trencher and a 4" trench shovels -these things are great!  I used 3" grey plastic conduit - which was the cheapest part of the job- it is WAY easier to pull wire through the bigger the diameter.

Regarding outlets and circuits.  It only took me 1 year to want more outlets.  And I installed plenty, with a big elaborate shop design plan.  This spring, I get to open up last years some Sheetrock and put in more wiring... hint, hint.

Also call before you dig...


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## CluelessNewB

I don't believe I have ever heard anyone saying something like "I wish I had run less power to my shop".   I have a relatively small shop ~576 sq feet with 100 Amp sub panel and every breaker is used.  Most of my stationary tools are wired for 220V.


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## Uglydog

My original plan was to run a buzz box and DP.
Things grew from there. 
I ran 6. Should have run 4. 
I occasionally have to go to the main panel in the house to reset a breaker.
Arrgh.

Daryl
MN


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## ewkearns

Personally? I'd go with 2-2-2-4 and a 100 amp sub panel. Just doing enough to get by for "today" will probably come back to bite you in the posterior "tomorrow."


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## mksj

If you are using 240VAC for the VFD, the breaker would need to be ganged, both legs would trip. I would not run 120 and 240 off of the same breaker. You might be able to put in an electrical sub panel for future upgrade and have two single pole 120VAC breakers and a separate 240 VAC ganged breaker. 

Like the others have mentioned, if you are going through all the trouble to trench and put in a new sub panel, then I would pull a minimum of a 100A line. I ran #4 copper wire in 1.5" ABS electrical conduit to my garage (about 40') and put in a 100A sub-panel. I believe code would require #3 wire for 100A breaker at the main panel (I use an 80A breaker at the main breaker box).  All the sub panel breaker slots are filled and I recently had to put in a quad pole circuit breaker for a compressor and two 120VAC circuits.  The VFD will give you soft start, so you do not have the motor start current that needs a bigger breaker. I think you would have too much voltage drop using #12 wire running a machine and anything else. I would also go a bit bigger on the conduit, you need to review the electrical code with regard to the fill volume (wires size and number) that can be pulled through the conduit.

I recently put in a Champion 5Hp compressor, they specify a 50A breaker. It is surprisingly quiet, it uses a low speed motor and air pump, and I can barely hear it outside of my garage. There is also the California Air compressors if you do not need higher volumes of air, they have about the same noise level as your mill when running.


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## wawoodman

More is better. When I set up the shop, I ran a 60 amp subpanel. I wish it had been 100.

And while you're running the receptacles, use 12 ga. wire, and 20 amp breakers. 14 ga./15 amp just doesn't cut it. And make sure the receptacles are 20 amp, as well.


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## stupoty

Not exactly on topic but .. 

I just changed out my workshop (cubby  hole) lighting for led flurecesent fitting of 50w, it has a maintained live and a battery that will keep half the lights on for upto 3h if the power drops might be worth considering if your going to be working at night in the dark  surrounded by spinny and sharp things 

They have got a lot cheeper, and you can get a small bulk head light as a very cheep one juat to give enough light to find your way out.

Stuart


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## tweinke

CluelessNewB said:


> I don't believe I have ever heard anyone saying something like "I wish I had run less power to my shop".   I have a relatively small shop ~576 sq feet with 100 Amp sub panel and every breaker is used.  Most of my stationary tools are wired for 220V.



I did a 100a panel and am tickled


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## mzayd3

I run my entire setup off of 240 volt, 20 amp. No issues at all. 

My vote says use what you have until there is a problem, then upgrade.


Sent from my iPhone using Tapatalk


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## mksj

So to answer the original question, the recommended wire for a 240 VAC single phase input 1Hp (0.75 kW) VFD is 12-14AWG with a recommended breaker/fuse of 15A. Assuming a 15A draw at 240 VAC the voltage drop for 70 feet of 12 AWG wire is about 1.4%, at 120 VAC it is 2.8%. The The NEC maximum conductor voltage drop recommended for both the feeder and branch circuit is 5 percent of the voltage source. So with a 20A main panel breaker feeding your 12AWG branch circuit to your detached garage should be OK, I still would consider a sub panel and breaking out two 120VAC separate 15A single pole breaker socket circuits for each set of 4 outlets,  and a 15A double breaker for a 240 VAC circuit. I also believe there is a requirement for all garage outlets to be on a GFI, the standard big box store GFI's usually trip when a VFD is attached to it.


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## ewkearns

stupoty said:


> Not exactly on topic but ..
> 
> I just changed out my workshop (cubby  hole) lighting for led flurecesent fitting of 50w, it has a maintained live and a battery that will keep half the lights on for upto 3h if the power drops might be worth considering if your going to be working at night in the dark  surrounded by spinny and sharp things
> 
> They have got a lot cheeper, and you can get a small bulk head light as a very cheep one juat to give enough light to find your way out.
> 
> Stuart



Magnetic contractors are your friend in a power outage....


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## Keith Foor

Hate to point this out, but.... It's never a good idea to sit and think about how little you are going to do and then subtract from what you think you need for power in a shop.  If you are not going to work in the shop, then forget about it.  Put up a sky light to get some light in and start building shelves to store crap on.  It's typically easier to begin building shelves in the middle of the floor so you can store as many things you will never use again on them.    OR you can do it with the idea that you WILL be working out there.  And buying equipment that will consume more power and build to accommodate it now.

I am not saying to get a new 400 amp service put in, but running 3 12 gauge runs of Romex ain't gonna cut it either.

First off, how big of a panel is in the house?  You can't exceed that so don't bother trying to.  If the main is 100 amp, then a 200 amp sub panel on it fed from a 200 amp breaker is pointless.   You can go 100% of the main, but no more than that.  and I wouldn't do that.  75% is where I would stop and 80% is a hard limit in my book.  Code's in your area may vary, so don't think I am quoting regulation,  I am not.
So lets size the wire for 80 AMP. 

Book says that you are looking at 4 gauge copper but that is for 50 foot.  I would go to 2 gauge and call it good for that distance. 
Cutting it in is easier that you might think.
Use a rototiller and just go from one building to the other over and over again.  Have a couple friends or kids walk behind you with shovels and clean out the trench until you are 2 foot or so down and lay the pipe.  Cover it up, put in the wire and go to town. 
get a used panel and an ebay breaker to feed it power and you are off to the races. 
Wire garage to the sub panel you installed and you are golden. 

If there is at any point, any doubt as to your abilities to do this work, stop and call a professional.


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## tq60

Forget ebay for panels.

We got our 200 amp capable subpanel with a good supply of breakers at home depot for 70 bucks.

The box stores have different sizes from small to large with breakers for decent money.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## ewkearns

tq60 said:


> We got our 200 amp capable subpanel with a good supply of breakers at home depot for 70 bucks.



One might, also, consider wiring in a Main Breaker Load Panel, if there is any thought that over 100 Amps will be needed. When I re-wired my (soon to be) workshop, I did so, knowing that an addition of a phase converter to existing lights and whatnot might exceed the capacity. If I find 100 A won't cut it, all I'll need to do is change some wiring, add a meter base, and pay the utility to connect.

NOTE: That wiring a subpanel and wiring a main breaker fed from the utility are two different animals. If you don't know the differences, you might want to get professional help...


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## TORQUIN

My garage is about 50 ft from the house. I ran 2 #4 wires for each leg. I had a tiny panel in there until I got into the lathes and mills. I found a 100A panel on CL and upgraded and have been very happy since. I have almost 0 voltage drop from the house and have never been able to blow the 100A breaker in the house, even when welding 3/8" aluminum. I suggest you go bigger than you think you need. Overkill is good in this situation.

Chris


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## jim18655

If you ran 2-#4 per phase in parallel then it's a code violation. NEC prohibits conductors smaller than 1/0 in parallel (310.10 (H)(1)). Also, most lugs on breakers and panels are not rated for more than one wire per terminal so you would have to splice them to a larger wire to connect to the panel.
I'd hate to see someone try it and get shot down in a building inspection.


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## ewkearns

jim18655 said:


> If you ran 2-#4 per phase in parallel then it's a code violation.



You would probably spend about 1/3 more in wire cost (minimum) to run 2-#4 wires vs., say, a #1 wire, which is roughly (but not quite) equivalent. Check your local codes, one #2 would probably be sufficient and meet code....


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## TORQUIN

jim18655 said:


> If you ran 2-#4 per phase in parallel then it's a code violation. NEC prohibits conductors smaller than 1/0 in parallel (310.10 (H)(1)). Also, most lugs on breakers and panels are not rated for more than one wire per terminal so you would have to splice them to a larger wire to connect to the panel.
> I'd hate to see someone try it and get shot down in a building inspection.



Bummer. My buddy that wired it is a licensed electrician, so I thought he knew what he was doing. Maybe he just cut a corner to save bucks in my situation.

Thanks for the info.
Chris


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## ewkearns

TORQUIN said:


> Bummer. My buddy that wired it is a licensed electrician, so I thought he knew what he was doing. Maybe he just cut a corner to save bucks in my situation.
> 
> Thanks for the info.
> Chris



Very likely so.....  he may have had a surplus of #4 wire left from a particular job. It is unlikely that (after the fact) any inspector is going to be rummaging in your panel. If it works, enjoy what you have...... others, that may have an inspector driven solely by the black and white of the NEC may not be so forgiving.....  IMHO, everything should be driven by common sense, an all to rare animal in this "Nation of Laws."


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## Bob Engelhardt

You have a baby?  Well, I can see why shop wiring is not a high priority budget item <G>.

For my shop, I have a  15A 240v circuit that runs VFD's for a drill press, lathe, and mill.  At 3.6KW, I could run 2 at once, but I'm not nimble enough to do that.

All the outlets (12?) are on one 15A 120V circuit.  A baby MIG is on that.  Lights are on a shared house circuit.

I know, "more is better", "better now than to have to upgrade later", yada yada.  But if I were you, I would pull a 12-3 wG through the conduit you have & put in a sub panel large enough to hold a 15A 240 & 2 15A 120's.  15A is big enough and 14ga wire is so much easier to handle than 12ga.  In other words: what you said.

This could satisfy your needs for years, depending.  Could probably even have a  moderate (20 gal) compressor on it.

Bob


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## ironhorse18

I haven't read every post word for word,,,,  but what size of the entrance to your house?  200Amp?  Do you have room for an additional 2 pole breaker in you main CB box?  It is exactly like everyone says..................  size up.

steve

Potential altitude is of no value.


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## abrace

I ran #2 THHN copper in conduit and protected it with a 125A breaker. #2 is good for 115A, but due to the next size up rule you can protect it with a 125A.

#2 is small enough it is still pretty easy to work with.


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## weaselfire

2/2/2/4 and 100 amp here as well.  70' you can hand trench quite easily in most soils, match electric code requirements for depth, wire size, etc.

In your 1/2" EMT you can run 4 #10 wires for 30 AMP 220.  If that can meet your needs.  Otherwise, you have to run new wire anyway.  12/3 with ground only gets you 20 amps.  One circuit.

How you're getting EMT to hold up underground beats me.

Jeff


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## Bob Engelhardt

weaselfire said:


> [snip]
> How you're getting EMT to hold up underground beats me.



That's a good point: your conduit may have corroded and collapsed, making a re-pull impossible.


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## whitmore

magu said:


> Hi all, I'm looking for some advice. I'm looking to add power to my detached garage ...the run will be 70', it will power some lights (>2amps), a little old radio, and 1... a 1 HP vfd to power both my mill and lathe (240 3ph, 3/4 and 1/2 Hp respectively) I will also install 8 outlets.
> .



If you want it up to code, it'll take a subpanel in the outbuilding with its own breakers.  Your lights and
outlets will have 120V breakers, and the VFD a 240V breaker, so a stalled motor doesn't leave
you in the dark...   Maybe there's already a breaker box there? 

General guidelines: for a farm outbuilding, #8 wire for up to 50 feet, #6 wire minimum for anything
farther.   Specifically, there's worksheets for totaling up loads (get _Wiring_Simplified_, H. P. Richter,
from the library if you want to see details),  but probably the smallest subpanel (60A) and #6 wire
are going to be required.


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## Rustrp

I've read most of the comments and you've gotten some good info. There's a couple of points I will make. Safety is a factor when you attempt to stretch electricity beyond the laws that govern it. One comment I read from ewkearns had flashing red lights. You electrical service from which you will be pulling to your shop is the key.  If you only have 100A then you may be stretching it. The electrical code dosen't say it's okay to it wire it like this, ________ (insert reason)? I know you stated you would be working when everything in the house is idle but on the occassion when it may be different?  The second item is the 1 hp vfd. It would be good to look at the full load amps (FLA) of what you are running vs looking at HP. When electric motors run at less than or more than how they are rated it reduced their life, and this includes speed. Slowing a motor down or speeding it up by less than or more than 20% is detrimental.  

With funds being a factor, my recommendation on pulling the wire would be to pull the correct size required. There's plenty of info on the net in regard to wire size, amperage, voltage drop, etc. You can use an undersized circuit breaker on the correctly sized wire, safely, but not an oversized breaker on incorrect wire size. I was taught to alway respect water, fire and electricity.


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## K3vyl

Run 2" pvc conduit out there and pull in wire for your present load. PVC conduit is cheap and digging is expensive. The 2" conduit could accommodate a 200 amp circuit in the future,should your needs increase.


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## ARKnack

One item that is never talked about in these thread is you voltage drop requirements. First I agree that the larger the wire the better, but better equals more expensive.
The original problem was the garage is approximately 70 feet. So assume a 100 foot run. The load requirements are lite, but allowing for future expansion lets assume 120 V @ 20 amps and 240 volt @ 30 amps. That amount of power will run most equipment. We can also assume a continuous load of 15 amps for lights and other small items. That mean a 120 V @ 35 amps. The National Electric code (NEC) recommends 3% voltage drop.





Doing a quick calculation, the recommended wire size is #8 for the 240V requirements but is #6 for the 120V needs. Note the multiplier show is incorrect, but calculations are correct.

Here are he calculations. Please note that the spread sheet isn't mine.


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## abrace

ARKnack said:


> One item that is never talked about in these thread is you voltage drop requirements. First I agree that the larger the wire the better, but better equals more expensive.
> The original problem was the garage is approximately 70 feet. So assume a 100 foot run. The load requirements are lite, but allowing for future expansion lets assume 120 V @ 20 amps and 240 volt @ 30 amps. That amount of power will run most equipment. We can also assume a continuous load of 15 amps for lights and other small items. That mean a 120 V @ 35 amps. The National Electric code (NEC) recommends 3% voltage drop.



Voltage drop is an important consideration, but I am not sure I agree with your calculations. Assuming the OP has a standard 120/240 split phase service, then only the unbalanced current between the hot legs ends up travelling back on the neutral.

Using your example above, with 20A of 120V for receptacles and another 15A for lighting, assuming that the single pole breakers are connected to different poles in the panel (and any panel should have its 120V breakers balanced!) then you only have a 5A delta between the legs, and the neutral will end up carrying that 5A.

In other words, you would end up with 15A of 240V and only 5A of 120V in that example. Add in the 240V loads and you have a total of 45 amps of 220V and only 5A of 120V.

In most cases the feeds to outbuildings end up carrying very little current over the neutral. In big installs, it is allowed to undersize the neutral compared to ungrounded conductors for this reason.


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## Rustrp

abrace said:


> Voltage drop is an important consideration, but I am not sure I agree with your calculations. Assuming the OP has a standard 120/240 split phase service, then only the unbalanced current between the hot legs ends up travelling back on the neutral.
> 
> Using your example above, with 20A of 120V for receptacles and another 15A for lighting, assuming that the single pole breakers are connected to different poles in the panel (and any panel should have its 120V breakers balanced!) then you only have a 5A delta between the legs, and the neutral will end up carrying that 5A.
> 
> In other words, you would end up with 15A of 240V and only 5A of 120V in that example. Add in the 240V loads and you have a total of 45 amps of 220V and only 5A of 120V.
> 
> In most cases the feeds to outbuildings end up carrying very little current over the neutral. In big installs, it is allowed to undersize the neutral compared to ungrounded conductors for this reason.



Wondering what you mean by split phase service? I agree with you if this is 3 phase but I'm pretty sure I read single phase in the question being presented along with the need for the VFD.


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## ARKnack

Don't completely disagree with you abrace. I am making some assumptions of the load and not balancing it.  I have seen that before. All 120 breakers on one side, 240v on the other. "Looks" pretty.  The 240 volts does indicate #8 as an option. This was more to indicate that there is more to wire sizing than current carrying capacity. Myself, I ran 170 feet of #4 to my barn. Breaker size is 60 amp. Could go to 70 amps. More than enough power to run everything I need.  Not even considering harmonics.


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## abrace

Rustrp said:


> Wondering what you mean by split phase service? I agree with you if this is 3 phase but I'm pretty sure I read single phase in the question being presented along with the need for the VFD.



Split phase is your traditional residential electric service in the USA. Basically it is a single phase 240V transformer out at the pole with a center tap. That center tap is grounded and becomes your neutral. Any circuit you run that uses a single hot and the neutral only gets half the windings at the transformer and develops around 120V RMS. A circuit that uses both hots gives you the entire winding width and develops the full 240V.

In a properly balanced panel the neutral sits there and does nothing.

You can see this working by using an amp clamp in your panel. Clamp one hot and take the reading. Clamp the other hot, take that reading. Then clamp the neutral and take a reading. You will see that the neutral is exactly whatever the difference between the two hots are.

Most panels balance out pretty well on their own as long as you fill the panel in order with a 120/240V split phase system.


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## abrace

ARKnack said:


> Don't completely disagree with you abrace. I am making some assumptions of the load and not balancing it.  I have seen that before. All 120 breakers on one side, 240v on the other. "Looks" pretty.  The 240 volts does indicate #8 as an option. This was more to indicate that there is more to wire sizing than current carrying capacity. Myself, I ran 170 feet of #4 to my barn. Breaker size is 60 amp. Could go to 70 amps. More than enough power to run everything I need.  Not even considering harmonics.



Even in that model with 240's on one side and 120's on the other you should end up in pretty good shape. Where people get into trouble is using only odds or evens, or hook up multi wire branch circuits but have both breakers on the same pole...which is a violation of course, but what happens is the neutral ends up melting.

170 feet is a long run, you can go all the way to 90A (next size up rule) with #4 if you run THWN2 in pipe, but that is a long way and voltage drop would be a killer. Seems like a smart approach bumping up a size. A little bit bigger wire doesn't cost much more.


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## Rustrp

abrace said:


> Split phase is your traditional residential electric service in the USA. Basically it is a single phase 240V transformer out at the pole with a center tap. That center tap is grounded and becomes your neutral. Any circuit you run that uses a single hot and the neutral only gets half the windings at the transformer and develops around 120V RMS. A circuit that uses both hots gives you the entire winding width and develops the full 240V.
> 
> In a properly balanced panel the neutral sits there and does nothing.
> 
> You can see this working by using an amp clamp in your panel. Clamp one hot and take the reading. Clamp the other hot, take that reading. Then clamp the neutral and take a reading. You will see that the neutral is exactly whatever the difference between the two hots are.
> 
> Most panels balance out pretty well on their own as long as you fill the panel in order with a 120/240V split phase system.



I understand the transformer arrangement, whether it's single of three phase. I'm just not sure how three phase applies to the original question asked. A balance single phase electrical panel seems more like an electricians myth than reality. Even if you have a single row of breakers down the middle or a double row of breakers in the panel the 220/240 breakers pull from the buss bar on the 110/120 side. It doesn't matter how you stack them in because the only difference between 220/240 and 110/120 breakers is the pin that trips both on the 220 breaker, and ohms law hasn't change. 

If a panel has two rows then it's logical to even up the sides, top down, but the buss bars are rated much higher than the panel rating. If you want balance because it looks pretty, I'll give it a thumbs up.


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## abrace

Balancing the load is no myth. As long as your neutral is fully sized it doesn't matter.

However, my point was that voltage drop calculations were being done at 120V. Voltage drop calculations should be done for 240V when looking at a split single phase feeder, and not for 120V. I was simply trying to explain why, from a feeder's perspective, you don't need to do drop calculations at 120V.


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## Rustrp

abrace said:


> Balancing the load is no myth. As long as your neutral is fully sized it doesn't matter.
> 
> However, my point was that voltage drop calculations were being done at 120V. Voltage drop calculations should be done for 240V when looking at a split single phase feeder, and not for 120V. I was simply trying to explain why, from a feeder's perspective, you don't need to do drop calculations at 120V.



If the feed was going to a sub-panel, yes you would add a neutral and the voltage drop would be calculated on the 240 feed. If the 240 was on a breaker inside the residence then there would only be two hot legs and a ground sized per NEC. Most wire size charts for amperage are based on 100' so voltage drop is already factored in. The reality of a need to balance a single phase panel is a myth. In reality the sub panel or main circuit breaker panel has been designed to compensate. You just can't unbalance a panel with one row of breakers and a person would need to work really hard to unbalance a panel with two rows by only using one one row and then if you look at the buss bars.............nah, can't be done.


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## abrace

Rustrp said:


> If the feed was going to a sub-panel, yes you would add a neutral and the voltage drop would be calculated on the 240 feed.



Yes, a feeder to a outbuilding is what is being discussed.



Rustrp said:


> The reality of a need to balance a single phase panel is a myth. In reality the sub panel or main circuit breaker panel has been designed to compensate.



I don't know what the sub panel/main breaker panel has to do with it. If you end up with a feeder to an outbuilding where you have 100A over hot A, and 20A over hot B, you wasted money on the feeder. That second hot is doing very little. You ran #3 out the building, when you could have run #6 if it was properly balanced.



Rustrp said:


> You just can't unbalance a panel with one row of breakers and a person would need to work really hard to unbalance a panel with two rows by only using one one row and then if you look at the buss bars.............nah, can't be done.



Yes, in this specific case discussing needing 2 circuits correct. My statements were just an intent to educate on voltage drop calculations for single phase services, and why they should be done at 240V. We really arent disagreeing, but it seems you think we are. You have to try to unbalance a single phase panel, hence why, again, my suggestion is to do voltage drop calculations at 240V. If you fully read my posts you will see I said:



			
				abrace said:
			
		

> In most cases the feeds to outbuildings end up carrying very little current over the neutral.





			
				abrace said:
			
		

> Most panels balance out pretty well on their own as long as you fill the panel in order with a 120/240V split phase system.





			
				abrace said:
			
		

> Where people get into trouble is using only odds or evens



See? We seem to actually agree.


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## Rustrp

1). Why are you referring to the commercial power source as a split phase?
2). If this is a feeder then it would be supplying a sub-panel in the outbuilding, protected at the main circuit breaker panel with a circuit breaker of fused disconnect box.
3). Voltage drop is a factor but a very small one. 
4). As a feeder the conductors would be three of the same size.
5). If this was a branch circuit (240 v) you would only have to hot legs and both the same size, plus the ground. 
6). How can you provide a 240 v feeder with two differnet size conductors?


----------



## abrace

Rustrp said:


> 1). Why are you referring to the commercial power source as a split phase?


Because that is what residential 120V/240V service is commonly referred to as by many, myself included. Call it whatever you like.



			
				Rustrp said:
			
		

> 2). If this is a feeder then it would be supplying a sub-panel in the outbuilding, protected at the main circuit breaker panel with a circuit breaker of fused disconnect box.


Correct, and code requires that for any more than a single circuit run to an outbuilding. You can't run 2 circuits to an outbuilding without putting in a feeder, panel, and ground rod. It is the only way to do it legally.



			
				Rustrp said:
			
		

> 3). Voltage drop is a factor but a very small one.


Agreed, I wasn't the one raising voltage drop as a concern.



			
				Rustrp said:
			
		

> 4). As a feeder the conductors would be three of the same size.


Most likely yes, although depending on the install the neutral could be smaller than the line conductors as long as it is properly calculated and meets requirements. In some cases, the neutral actually has to be bigger.



			
				Rustrp said:
			
		

> 5). If this was a branch circuit (240 v) you would only have to hot legs and both the same size, plus the ground.


Correct again, but I think you misunderstood my post. I was saying of 100A on leg A and 20A on leg B then I need to size the feeder for 100A, meaning I would use #3 assuming conductors in pipe. If I rebalance the load by moving single pole breakers to swing 40A of load from leg A to leg B, then I would have 60A for each leg and now I would only have needed a 6AWG feeder. These problems tend to happen a lot more in commercial settings than residential. Again, as I said, things generally balance themselves.

I have run into 120V inverter based solar systems were balancing can be a problem, but that is an edge case nowadays.

In commercial settings with UPSs, balancing the 120V loads is critical. I actually had to do that in January. A UPS was slipping into soft bypass because it was overloaded all because one of the 2 legs was much hotter than the other. I moved some of the loads to the other leg, and the UPS went from over 100% utilization (where it goes into bypass) down to the low 90's.

It may not mean much to some, but this allows my company to defer the UPS upgrade to next year.



			
				Rustrp said:
			
		

> 6). How can you provide a 240 v feeder with two differnet size conductors?


Who suggested that and how did you read that into my post? That said, see comment above about neutral. However, my previous post was not advocating using 2 different size conductors for the feeder. Just that if my example 100A/20A load had been properly calculated at the start, and balanced effectively, then the feeder could have been installed as a 6AWG feeder to begin with. Balancing the load properly most efficiently uses both line feeder conductors.

At this point I am done at this discussion. I feel that you are intentionally trying to twist my words and interpret what I am saying differently to try to make me out to look like an idiot. For what reason I do not know, but I am done with it. This forum isn't about that.


----------



## ewkearns

In the South, a few decades ago, some machine tools that were very "_affordable_" hit the used market.....  These were machines coming out of regions in the north that were designed for 2-phase power (_voltage differing by 90°_)... these were 4-wire systems, though some of them were fed with 3 wires, a large diameter "_common_" wire and two smaller "_hots._" Some were, I am given to understand, even powered by two different generators. Those systems were split phase, but not single phase.

So, I think "_split phase_," in this sense, is probably a regional use of the word. Technically, it is correct as our "_single phase_" (voltage differing by 180°) power is derived by split voltages from a center tapped transformer. Single phase implies that the two legs are in phase and, are thus, additive (_120V + 120V = 240V_). Split phase, on the other hand, doesn't necessarily carry that distinction. Single phase is probably a better descriptor for that tingly stuff hiding behind the outlets in our homes and garages.

Purchasers of the above affordable machines quickly discovered that split phase motors (_2-phase_) don't run on polyphase (_3-phase_) power *or* single phase power.....


----------



## projectnut

We had our garage professionally rewired about 10 years ago.  The electricians ran about 80' of 4 gauge 3 conductor wire to a 100 amp service.  There are 2, 50 amp outlets, 2, 30 amp outlets, about a dozen 20 amp outlets around the perimeter and another half a dozen in the ceiling for lighting.


----------



## tq60

Balance panel is no myth.

First home had most all loads on one side and resulted in cooked panel parts.

Was older home with aluminum wire that had old and cruddy grease on connectors.

Meter would get hot to touch.

The theroy is simple and the neutral carries the non balanced loads if and when load is not balanced which is often in shop with lots of 120 volt equipment with large motors.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## Rustrp

tq60 said:


> Balance panel is no myth.
> 
> First home had most all loads on one side and resulted in cooked panel parts.
> 
> Was older home with aluminum wire that had old and cruddy grease on connectors.
> 
> Meter would get hot to touch.
> 
> The theroy is simple and the neutral carries the non balanced loads if and when load is not balanced which is often in shop with lots of 120 volt equipment with large motors.
> 
> Sent from my SAMSUNG-SGH-I337Z using Tapatalk



Aluminum wire and the result of using isn't as a good example for an unbalanced. There's a myriad of reasons for the failure or overheating but the first is using aluminum wire. Unfortunately an electrical service using aluminum wire requires maintenance. Aluminum wire manufacturers swear this isn't the case. Unfortunately the home owners doesn't know this. The "cruddy grease" Noalox, which is a nonconductive grease and zinc powder mix, is placed on the connection to prevent oxidation or corrosion caused by dissimilar metal. The expansion and contraction of aluminum wire due to heat causes loose connections, in electrical service panels.

"The theroy is simple and the neutral carries the non balanced loads if and when load is not balanced which is often in shop with lots of 120 volt equipment with large motors."

Yes, this would be/could be true if the service is 3-phase. What standard voltage range uses the common as a conductor?


----------



## magu

Thank you all for taking the time to comment, whether it was constructive or not. To the handful who read what I am trying to do and, maybe more importantly, why I am not doing more, and provided relevant feedback I appreciate it as that is what I was looking for by starting this thread. 

On the note of technical discussion, I do plan to install a sub-panel, off of which I will run one 240V circuit and two 120V circuits. I have no idea how the emt is still there, but I can run a fishing tape through so I think I will be good, and yes it is emt not rigid. Anyone have a suggestion for a GFI breaker that won't fight with my VFD? While I don't intend to tell the township what I am doing (they would lose it if they came in for inspection and saw the knob and tube), I do want to do everything right. I am a mechanical engineer, so the NEC is far from my wheelhouse, but this is not the first time I have used it, I just like to consult with others when I'm outside my comfort zone.  

I do not intend to come off as arogant or angry that someone disagrees with what I am doing, but consider this. The large majority of replies (aside from a recent patter of discussion about analysis methods which I don't mind a bit) simply statedin some form: "I used ____ (insert big wire/amp size), you should too" or "that won't be enough, just bite the bullet and install a big service" I would absolutely love to do that, I am not trying to skimp by to be cheap or lazy. I am trying to make what I have work so that I can use what equipment I have now, rather than let it wait for years. When you are responding to these types of threads, keep in mind your audience may not be in the same place in life so, while personal experience and recommendations are great, maybe try not to come off acting as though what you have done is the only way, it can be a bit discouraging. Also, I live in the hills outside of Pittsburgh, if anyone who attests to how quick and easy a trench would be to dig wants to show me, I would love the help. Don't bother bringing a shovel, we will start with matocks and move to digging irons. The trench will come in time, but it won't be a weekend project. 

This is the one statement kin the thread which I actually find quite offensive: 



Keith Foor said:


> Hate to point this out, but.... It's never a good idea to sit and think about how little you are going to do and then subtract from what you think you need for power in a shop.  If you are not going to work in the shop, then forget about it.  Put up a sky light to get some light in and start building shelves to store crap on.  It's typically easier to begin building shelves in the middle of the floor so you can store as many things you will never use again on them.    OR you can do it with the idea that you WILL be working out there.  And buying equipment that will consume more power and build to accommodate it now.



Perhaps I am in a small majority that folks these days don't understand, but I am trying to take care of my family and my responsibilities. When all that is done, I try and sneak out to the garage and pursue my personal passion. Unfortunately, that meanes digging a trench and installing a large service comes after buying diapers, paying for daycare, sending my wife occasional flowers, doing dishes, updating the house, saving for someone elses college, and sitting on the floor building lego towers for a toddler (who has no appreciation for their architectual beauty) to knock down shortly before running off in a vain effort to catch the infinitely quicker dog. So no, I am not "sitting around thinking about how little I am going to do" I am working damn hard and knowing that my hobby needs to come absolutey last on the priority list.


----------



## Rustrp

abrace said:


> Because that is what residential 120V/240V service is commonly referred to as by many, myself included. Call it whatever you like.
> 
> 
> Correct, and code requires that for any more than a single circuit run to an outbuilding. You can't run 2 circuits to an outbuilding without putting in a feeder, panel, and ground rod. It is the only way to do it legally.
> 
> 
> Agreed, I wasn't the one raising voltage drop as a concern.
> 
> 
> Most likely yes, although depending on the install the neutral could be smaller than the line conductors as long as it is properly calculated and meets requirements. In some cases, the neutral actually has to be bigger.
> 
> 
> Correct again, but I think you misunderstood my post. I was saying of 100A on leg A and 20A on leg B then I need to size the feeder for 100A, meaning I would use #3 assuming conductors in pipe. If I rebalance the load by moving single pole breakers to swing 40A of load from leg A to leg B, then I would have 60A for each leg and now I would only have needed a 6AWG feeder. These problems tend to happen a lot more in commercial settings than residential. Again, as I said, things generally balance themselves.
> 
> I have run into 120V inverter based solar systems were balancing can be a problem, but that is an edge case nowadays.
> 
> In commercial settings with UPSs, balancing the 120V loads is critical. I actually had to do that in January. A UPS was slipping into soft bypass because it was overloaded all because one of the 2 legs was much hotter than the other. I moved some of the loads to the other leg, and the UPS went from over 100% utilization (where it goes into bypass) down to the low 90's.
> 
> It may not mean much to some, but this allows my company to defer the UPS upgrade to next year.
> 
> 
> Who suggested that and how did you read that into my post? That said, see comment above about neutral. However, my previous post was not advocating using 2 different size conductors for the feeder. Just that if my example 100A/20A load had been properly calculated at the start, and balanced effectively, then the feeder could have been installed as a 6AWG feeder to begin with. Balancing the load properly most efficiently uses both line feeder conductors.
> 
> At this point I am done at this discussion. I feel that you are intentionally trying to twist my words and interpret what I am saying differently to try to make me out to look like an idiot. For what reason I do not know, but I am done with it. This forum isn't about that.



I wasn't attempting to twist your words, I was attempting to untwist. Not only for myself but other readers. The original question presented was in regards to residential power so introducing an anecdotal commercial power issue with UPS being the example is a twist. I understand that geographics and demograpics play a large part in how we express ourselves. 

As *ewkearns * stated in his last comment, split-phase was the forerunner of our current single phase supply. It's a 19th century power source that was used in a specific geographical area. Specific geographically because power lines to other parts of the country had not been strung yet. By the time power was supplied the issues with split-phase were out in front and transformers had changed or were in the process of change. 

I'm no electrical engineer but I cringe when unproven electrical theory is presented as fact. It's easy to unbalance a 3-phase electrical service, but taking this and applying it to a residential application and telling/selling a home owner on an estimate to upgrade and rebalance their electrical service is ethically wrong. It does happen and it happens often. Yes, I do agree you were presenting voltage drop, but you were also presenting an electrical panel being out of balance based on circuit breaker placement, whereas in a single-phase service, it just isn't going to happen. 

Another area with a twist is switching between feeder and branch circuit conductors. A 240v (single phase) branch ciruit requires two hot legs equally sized and a ground. A 240v (single phase) feeder requires three equally sized conductors comprised of two hot legs and a common.


----------



## Rustrp

magu said:


> Thank you all for taking the time to comment, whether it was constructive or not. To the handful who read what I am trying to do and, maybe more importantly, why I am not doing more, and provided relevant feedback I appreciate it as that is what I was looking for by starting this thread.
> 
> On the note of technical discussion, I do plan to install a sub-panel, off of which I will run one 240V circuit and two 120V circuits. I have no idea how the emt is still there, but I can run a fishing tape through so I think I will be good, and yes it is emt not rigid. Anyone have a suggestion for a GFI breaker that won't fight with my VFD? While I don't intend to tell the township what I am doing (they would lose it if they came in for inspection and saw the knob and tube), I do want to do everything right. I am a mechanical engineer, so the NEC is far from my wheelhouse, but this is not the first time I have used it, I just like to consult with others when I'm outside my comfort zone.
> 
> I do not intend to come off as arogant or angry that someone disagrees with what I am doing, but consider this. The large majority of replies (aside from a recent patter of discussion about analysis methods which I don't mind a bit) simply statedin some form: "I used ____ (insert big wire/amp size), you should too" or "that won't be enough, just bite the bullet and install a big service" I would absolutely love to do that, I am not trying to skimp by to be cheap or lazy. I am trying to make what I have work so that I can use what equipment I have now, rather than let it wait for years. When you are responding to these types of threads, keep in mind your audience may not be in the same place in life so, while personal experience and recommendations are great, maybe try not to come off acting as though what you have done is the only way, it can be a bit discouraging. Also, I live in the hills outside of Pittsburgh, if anyone who attests to how quick and easy a trench would be to dig wants to show me, I would love the help. Don't bother bringing a shovel, we will start with matocks and move to digging irons. The trench will come in time, but it won't be a weekend project.
> 
> This is the one statement kin the thread which I actually find quite offensive:
> 
> 
> 
> Perhaps I am in a small majority that folks these days don't understand, but I am trying to take care of my family and my responsibilities. When all that is done, I try and sneak out to the garage and pursue my personal passion. Unfortunately, that meanes digging a trench and installing a large service comes after buying diapers, paying for daycare, sending my wife occasional flowers, doing dishes, updating the house, saving for someone elses college, and sitting on the floor building lego towers for a toddler (who has no appreciation for their architectual beauty) to knock down shortly before running off in a vain effort to catch the infinitely quicker dog. So no, I am not "sitting around thinking about how little I am going to do" I am working damn hard and knowing that my hobby needs to come absolutey last on the priority list.



Thanks for the reply and chuckle regarding the trench...........I grew up in Florida and have visited Pennsylvania...I dig. 

My comments to you were code and safety related. Code: What you pull conductors through is important and size is important. Let me address what you pull the conductors through. EMT isn't for direct burial and you may have EMT or it could be ridgid? The condition at this point is most important and it's a family matter. If you pull a conductor through damaged conduit you take a chance of skinning the conductor. Current flowing back through the damaged metal conduit (doesn't matter if it's EMT or Rigid) to ground doesn't care who's hand is in the sink full of water when they are electrocuted. Sidebar: This is one reason 110v plugs are polarized. It separated the hot leg from the **common and ground** which is mistaken sometimes by the novice handyman as unimportant, or based on when the common connects in the service panel.

The skinned wire may end up in an air space not touching anything. When the conduit floods with water....what then?  The code is written for many reasons and safety is the primary one. -Russ


----------



## magu

Rustrp: I've worked on farms in Florida, I'll take digging in rocks over fire ants and mosquitoes any day. 

I have an appreciation for code concerns so long as logic rules, and absolutely for safety. Gone are my days of working with live wires instead of walking to the breaker. 

I can't say for sure what the conduit is under ground but it looks to be EMT when. It comes through the wall. It is also very old, so it might be none of the above. I've run a metal fish tape through it and not encountered any resistance of note, it also shows no signs of moisture intrusion and my basement has a spring continuously filling a cistern in the basement, the soil is very wet. The fact that there is no trace of water makes me think it is structurally intact, but I intend to run the new wires inside of Kevlar sleeving as an added measure. (Oh the fun things you can get for free when you work in weird industries)


----------



## Keith Foor

Well, if I offended you, don't think you are somehow in a small group of people.  I offend a LOT of people.  
That being said.  
First question I would ask on this, why do you need to bury the cable to begin with?  Is there a law that says it can't be done with areal cable?  
Poles are reasonably cheap if needed and you could run areal wire out to the building and eliminate the trench and rigid pipe path.

Now for a bit of reason to do as much as you can instead of going with a minimum.  
Say you feed it with the 3 runs of 12/2 that someone suggested.  And then a killer deal on a larger lathe that needs 30 amps to run falls in your lap. 12 gauge wire is good for 20 amps not 30.  
Point here is finding machines on the used market is sort of funny when you are on a budget.  First the little table top 110 units are there.  The Central Machinery stuff from harbor freight and similar low buck low quality gear.  Then you get into the mid sized gear that people want new prices for (at least in my area of central Ohio and you aint far enough away that Ohioians aren't buying there) and it's 40 years old or better.  But that's what everyone wants so they will pay the premium.  Then you get into the bigger industrial gear that is heavy and hard to move and the price goes back down.  But that stuff uses bigger motors and requires more power.  But it's cheap to buy.  Dragging something home to find out it can't be used sucks alot more than not having it at all.  Trust me.  I too know about being broke.  Watching stuff rust away that I didn't  have the money to invest in at the time and it sat and was ruined.  

As far as how to do it on a shoestring.
First it doesn't ever happen overnight.  It takes time to put together everything you need to do a project.  Electrical systems don't come in a box that you buy and assemble.  And that's actually a good thing, because you can buy your wire this week or month or whatever and maybe get some 4 square boxes to put outlets in and then next week get the outlets and faceplates.  Once you have that stuff then it's the panel.  and then later the breakers.  do it slowly and it will come together.  
The other thing to do is check the scrap yards for rolls of wire and long sections of cut wire.  
As long as it's long enough and the correct gauge then it will work.  Color isn't important.  If it's all orange, so be it.  You grab a roll of white, black, red and green tape and mark your conductors.  

So don't be offended,,, be motivated to figure it out.  Or be offended and let that motivate you.  Yes, family comes before all else.  Don't assume I don't know about that either.


----------



## tq60

That reminded me of something...

Buy one roll of wire!!!

We needed to put a sub panel in shop off of shop panel and cable distance was say 50 feet.

Buying by foot cable in 4 colors was one price but buying 500 foot roll of black was less...much less.

Used tape to mark each conductor and all is good and we have substantial amount left on roll for large load outlets for welders someday.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


----------



## British Steel

stupoty said:


> Not exactly on topic but ..
> 
> I just changed out my workshop (cubby  hole) lighting for led flurecesent fitting of 50w, it has a maintained live and a battery that will keep half the lights on for upto 3h if the power drops might be worth considering if your going to be working at night in the dark  surrounded by spinny and sharp things
> 
> They have got a lot cheeper, and you can get a small bulk head light as a very cheep one juat to give enough light to find your way out.
> 
> Stuart



Same, but mine are fluorescent rescued from the skip when my (very eco-conscious) workplace went over to LED lighting - positioned to light the main breaker panel for house and shop as well as the spinny sharp things, cost me not a penny apart from the twin & earth to wire them in!

Dave H. (the other one)


----------



## stupoty

British Steel said:


> Same, but mine are fluorescent rescued from the skip when my (very eco-conscious) workplace went over to LED lighting - positioned to light the main breaker panel for house and shop as well as the spinny sharp things, cost me not a penny apart from the twin & earth to wire them in!
> 
> Dave H. (the other one)



Not a penny now that's a total bargain   I've got a couple of T8 LED "Tubes" I think you can upgrade to them when your tube gets dim.  Presumably the current battery backup in your maintained fitting drives a 240v inventor so might be compatible.  I'm driving mine with T8 end caps wired direct to 240v no drivers.

(apologies for dragging the posts off topic) :0

Stuart


----------



## Rustrp

Keith Foor said:


> Well, if I offended you, don't think you are somehow in a small group of people.  I offend a LOT of people.
> That being said.
> First question I would ask on this, why do you need to bury the cable to begin with?  Is there a law that says it can't be done with areal cable?
> Poles are reasonably cheap if needed and you could run areal wire out to the building and eliminate the trench and rigid pipe path.
> 
> Now for a bit of reason to do as much as you can instead of going with a minimum.
> Say you feed it with the 3 runs of 12/2 that someone suggested.  And then a killer deal on a larger lathe that needs 30 amps to run falls in your lap. 12 gauge wire is good for 20 amps not 30.
> Point here is finding machines on the used market is sort of funny when you are on a budget.  First the little table top 110 units are there.  The Central Machinery stuff from harbor freight and similar low buck low quality gear.  Then you get into the mid sized gear that people want new prices for (at least in my area of central Ohio and you aint far enough away that Ohioians aren't buying there) and it's 40 years old or better.  But that's what everyone wants so they will pay the premium.  Then you get into the bigger industrial gear that is heavy and hard to move and the price goes back down.  But that stuff uses bigger motors and requires more power.  But it's cheap to buy.  Dragging something home to find out it can't be used sucks alot more than not having it at all.  Trust me.  I too know about being broke.  Watching stuff rust away that I didn't  have the money to invest in at the time and it sat and was ruined.
> 
> As far as how to do it on a shoestring.
> First it doesn't ever happen overnight.  It takes time to put together everything you need to do a project.  Electrical systems don't come in a box that you buy and assemble.  And that's actually a good thing, because you can buy your wire this week or month or whatever and maybe get some 4 square boxes to put outlets in and then next week get the outlets and faceplates.  Once you have that stuff then it's the panel.  and then later the breakers.  do it slowly and it will come together.
> The other thing to do is check the scrap yards for rolls of wire and long sections of cut wire.
> As long as it's long enough and the correct gauge then it will work.  Color isn't important.  If it's all orange, so be it.  You grab a roll of white, black, red and green tape and mark your conductors.
> 
> So don't be offended,,, be motivated to figure it out.  Or be offended and let that motivate you.  Yes, family comes before all else.  Don't assume I don't know about that either.



There's no law that says it can't be done above ground (aerial) but the laws are are more plentiful on how you go about doing it. The task of getting the wiring into and out of the building are more complicated. Just one example.


----------



## 4GSR

You can do as I did a few years back when I had my 20" L & S lathe.  I ran 90 feet of 6ga. SO cord from the meter/breaker box to the lathe. Tied to a 50 amp breaker or I should say, had a 50 amp outside plug mounted on the breaker box that the SO cord connected to.  Worked out nice.  When not in use, unplug, roll up the SO cord, yeah, 90 feet of 6 ga. cord gets heavy, too, put away in storage.  I have several lengths of SO cord that I use for various machine/motor applications in my shop.  And yes, I use a appropriate amperage size breaker/fuses for each installation.


----------



## Keith Foor

Thought of something else.  In sourcing a panel and the feeder cable for the main run to the barn.  
Find houses that are being torn down and ask for the panel and wire.  Don't bother with pulling wire out of the wall but a workable panel is a workable panel.  Also, if the house had overhead feeder coming from the street then grab that too. 
It will typically be aluminum wire but that's ok.  
It's common to be spliced together so if you need to get 3 sections and put them together to make it work then that's ok as well.
Thing with joining them is they have to have crimped barrel connectors used to be done right.  
The tools for these barrels are very pricy so have an electrician do the splices on the cable.


----------



## magu

So on the note of running above ground.... I'm putting in a fence that will run directly from the back corner of the house to the garage. While certainly not orthodox,  would there be anything wrong (code wise) with running along the fence? Im thinking I could run ridgid or thermoformed pvc under the botom rail? 1" I could out a facce board on the inside of the rail to hide it, and it would be off the ground and away from danger.


----------



## jim18655

magu said:


> So on the note of running above ground.... I'm putting in a fence that will run directly from the back corner of the house to the garage. While certainly not orthodox,  would there be anything wrong (code wise) with running along the fence? Im thinking I could run ridgid or thermoformed pvc under the botom rail? 1" I could out a facce board on the inside of the rail to hide it, and it would be off the ground and away from danger.



No problem at all as long as you can meet the support requirements and it's protected from damage. PVC should have an expansion fitting for the length so it doesn't twist and bow and pull the straps off. Good idea.


----------



## tq60

Before spending bucks or labor make a few sketches and call them plan a to plan X and visit your local building department and they will give correct advise to what is required where YOU LIVE.

It may be less work or money and be better too...better to ask.


Another way to "cheat" is to use a plug in to connect.

Say it is a 50 amp total then at the main panel install a 50 amp outlet and use 50 amp plug and wire to supply sub.

Now it is nothing more than an extension cord...used that trick way back when inspector was having fits due to too many staples holding romex...Second inspector gave advise to circumvent first pain in rear inspector.


Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## LarryJ

jim18655 said:


> Are you using direct bury cable or conduit? You could save on the expense now by installing a large (2") PVC conduit and up-size the wire later. It's more expensive overall but might help you out now.  I wouldn't do less than 100 amps for the equipment you listed. The welder might have substantial draw and don't forget about running some type of heat in the winter.



That's a great idea, Jim, and it wouldn't cost but $50-100 to do.


----------



## LarryJ

magu said:


> Hi all, I'm looking for some advice. I'm looking to add power to my detached garage so I can run my machines and do a bit of tinkering. My question is what size wire I need, the run will be 70', it will power some lights (>2amps), a little old radio, and 1 thing at a time (it's just me, I can't weld, run a mill and a sander all at once). I will be installing a 1 HP vfd to power both my mill and lathe (240 3ph, 3/4 and 1/2 Hp respectively) I will also install 8 outlets.
> 
> Can I use 12/3g wire for this?
> 
> My plan would be to put half the lights and half the outlets on each circuit breaker, that way if I blow a breaker I won't lose all my lighting. I would then use both legs to feed my vfd as well.



Lighting on one leg and outlets on the other is the norm, I believe. 

Ditto the suggestions to put in a load panel.  A 200a service box is only $40 more than a 100a, too.  If you're doing it yourself, you're already saving $500-1,000, so splurge.  <g>

I'd run 12/3 in the shop for the 120v outlets and 10/3 for the 240v outlets for upgraded welders in the future.  I added three 240v outlets in my 2-car shop after moving in and they'll handle the welders.  Looking back, I should have put in five 240v outlets since I have wood and metalworking tools.  Instead, I built a 30' 10/3 twistlock extension cord later.


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## autonoz

There are so many variables when deciding what to do. With what your doing I would not go less than a 60 amp sub panel. Now you will need to go on line and locate a chart that will give you the size wire which I am pretty sure is #6 and what size conduit you can run #6 through. If you use EMT you will want 3/4. Do your research and do it right the first time. Definately run seperate circuits for your outlets and lights. 20 amp for outlets with #12 wire. I just installed a 100 amp subpanel with main breaker in panel. #2 AWG wire through 1 1/4 conduit. All my shop circuits are 20 amp and will also be putting in 240 once I decide where my machines are going to be. Make sure your first outlet is a GFI, then your others can be regular outlest run in a series behind it. If your pulling a permit make sure you follow code as it will bite you in the hind end later. Also for safety reasons. I cannot stress enough to do the research on wire size, conduit size for wire fill,  and j box sizes for wire fill. Also make sure you are not running more conductors through the size conduit you are using if you are running conduit inside and multipe circuits through the same conduit. Ground all boxes and use seperate neutral for each circuit. You can share grounds with more than one circuit. Again if running conduit inside go 3/4 conduit for multiple circuits it will make pulling wire much easier than through 1/2"


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## Blackjackjacques

For your small simple single phase system fed from 240 V - a quick way to figure out what you need - 
Sum the kW ratings of all the equipment you think you will be running at the same time, and add a 50% load growth margin.  
Then divide that number by 240 V to determine conductor ampacity (size).
So lets say you sum up the kW rating of all your simultaneous equipment to be 5 kW, for example. Plus 50% makes that 7.5 kW,  and 7.5 kW/240 = 31.25 amperes.  If you are using UF-B, you can use No. 8 protected by a 40 A 2-pole breaker    Despite what the code permits, I never like to run UF without some protection, and I frequently use either liqua-tite flexible conduit, or PVC conduit.  

If you doubled up No.4, then you have plenty of capacity and the doubling up of conductors may not be an issue for your jurisdiction.  It will depend on what edition (and sections) of the NEC your jurisdiction adopts --  if any.  Additionally, such a practice is permitted in many other venues and is an accepted and safe practice if basic rules are followed - which is likely the case in your circumstance of being installed by a licensed electrician.

Good luck


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