# Electrical Feed question



## Walt (Aug 11, 2013)

I'm out of available connections at my 100A breaker box.

In order to run my Monarch 10EE lathe (1941 motor-generator) I need to use the 220v circuit that now powers the 5hp air compressor in my garage. The lathe is now in my basement workshop at the other end of the house, about 35' away from the garage. The breaker for the compressor is 20 A and has never tripped. I purchased a 40 A breaker for the lathe (actually for the rotary phase converter that will run the lathe). I have a 125' coil of #8 3 conductor cable plus ground for the to-be-upgraded circuit.

I'd like to connect the upgraded circuit so I can run either the compressor or the lathe. My first concern is the upgraded breaker will be too large for the compressor and maybe not trip the circuit if the compressor overheats. If that won't be a problem then what's the best way to do connect the parts together? I see three possibilities. 

One is to run the cable through the receptical box at the compressor and on to the shop. This results in the fewest connections (but only if the cable can be paired up on the receptical) and fewest boxes, but at the expense of some extra cable.

Second option is to branch the cable at the garage wall with a short leg going to the compressor, and a long leg going to the lathe. The overall length of cable is less than option #1, but there is an additional electrical box to set up.

Third option is to run full lengths of cable for both the compressor and the lathe back to the breaker box. This results in the fewest breaks in the cable, but uses the most cable. I don't know if it's legal (or even possible) to connect 2 sets of cable at the breaker.

Your thoughts? Maybe I just need to bite the bullet and put in a new, larger breaker box, but money is a factor.

Walt


----------



## awander (Aug 11, 2013)

As far as I know, it is NOT kosher to connect 2 wires directly to one breaker. you could always put a small junction box right near the breaker panel, though.


----------



## DMS (Aug 11, 2013)

We had our service panel upgraded to 200A when we moved in because I figured it would be an issue eventually, and I didn't want to deal with it later. The garage was not very well wired, so we pulled a feeder line in, and installed a sub panel. From there, we wired the rest of the garage. Upgrading your main service panel is going to be pricey; I think we payed about $4k (had a few other bits of work done at the same time).  We are in the California bay area, so everything is more expensive here. We did the sub-panel ourselves, as well as all the garage wiring. 

Personally, I think it would be cleaner to run to a sub-panel, that way you can add separate breakers and runs for your large equipment so that they are properly sized. Keep in mind that if you are going with the #8, you will not be able to exceed 40A. If it were me, and I were planning on staying in the house for a while, I would go for a heavier conductor. That way, if you upgrade your main service panel, you can just upgrade the breakers, and the wire will already be sized correctly. Of course, that is going to depend on your situation; if the wire pull is short/easy, and you already have the #8, not much risk in going with a 40A circuit to serve your immediate needs.


----------



## DMS (Aug 11, 2013)

awander said:


> As far as I know, it is NOT kosher to connect 2 wires directly to one breaker. you could always put a small junction box right near the breaker panel, though.



The breakers in my panel (at least some of them) are designed to allow 2 conductors (Square D Homeline). The clamp straddles the hold-down screw, and there is a place for a conductor on either side. IIRC this is only the 15/20A breakers. I think the 30/50A breakers are designed for a single, larger conductor. In any case, if the breaker is not designed for it, you shouldn't do it. 

There is also something like this, which lets you attach multiple circuits in a single double wide package

http://www.amazon.com/Square-Schnei...r=8-2&keywords=homeline+circuit+breaker+20/40


----------



## icore3user (Aug 11, 2013)

how old is your 100 amp panel?
are you using full size breakers?
who makes it ( Cutler Hammer, GE, etc.. )
Most 100 amp panel ( depending on their size ) are 12/24 panels 12/20 or varaints... that is 12 full size breakers with space for up to 
24 thin breakers for max capacity of 24 circuits.

it's always better to have 2 separate home runs back to the panel to each piece of equipment, that's how i have my lathe, mill and independent feeds for anything else
that I have in my garage ( welder at 40 amps @ 240v mill and lathe both 20amps / 240v, dedicated outlets for washer , dryer, xmas lights, benchtop gfcis )

it is not code to share a feed for equipment that should always be feed with dedicated feed.

some panels will have a circuit directory allowance with a graphic showing where you can place slim breakers ad tandems combos ( like a 40/ 20 20 / 40 ), which would take up
2 slots yet allow a 40 amp 240v fee plus 2 inside 20 amp 120v circuits. You would add another tandem combo breaker to relocate other circuits as you displace them with
another tandem combo breaker and re land then back on the tandem combo breaker. The key thing when doing this is to watch for phasing on the 120v circuits, especially if they share a neutral ( multi wire branch circuit ), you need to make sure they are landed back on the same leg ( A or B ) that they used to be on when they are relocated. For dedicated 120v circuits ( not shared neutral ) it does not matter how you relocated them, as there is issue of over loading the neutral.

http://www.startribune.com/local/yourvoices/140688183.html

the above link shows a good article on panels that can use slims / tandems or not.

- Al


----------



## Hawkeye (Aug 12, 2013)

Walt, Al is asking the right questions. If you could post a photo of your panel, we would be able to make better suggestions. I just added a sub-panel to my house last week, just to get a few more spaces. It is beside the main panel, but facing into the garage. I just used a 40 amp breaker to feed it, but I can raise that to 50 or 60 later if I need to (#6 copper).

DMS, even though Square D used the clamping plate for their smaller breakers instead of a set screw clamp, you are not allowed to connect two wires to one breaker, or to have any splices inside a panel. The one exception in the past was that the doorbell transformer was sometimes run to a convenient breaker when the transformer was mounted in the side of the panel. Hasn't been done that way for years.


----------



## DMS (Aug 12, 2013)

I have the type of breaker shown in the top picture of this link

http://www.structuretech1.com/2010/01/how-to-correct-double-tapped-circuit-breakers

From other info I have read, it's acceptable practice if the breaker is designed and labeled for it, though as everything, it may vary on jurisdiction. The inspector didn't actually look inside the panel (they mostly walk in, glance around the room, then say "looks good") so they may have complained, but it was on the diagram. :shrugs:

In any case, this brings up a good point, you should be able to call your local building inspector and ask them. Our local guys have been very helpful about answering questions about how they like to see things done, what's allowed, etc.


----------



## Starlight Tools (Aug 12, 2013)

I will second the sub panel route.  I have my SQ D panel stacked with dual breakers and was out of room, but I managed to free up enough slots to put in a sub panel by moving some of the load over to the sub panel.  Now I have all the shop on its own sub panel and do not need to run back to the house panel if I blow a breaker.

Walter


----------



## stupoty (Aug 12, 2013)

DMS said:


> We had our service panel upgraded to 200A when we moved in because I figured it would be an issue eventually, and I didn't want to deal with it later. The garage was not very well wired, so we pulled a feeder line in, and installed a sub panel. From there, we wired the rest of the garage. Upgrading your main service panel is going to be pricey; I think we payed about $4k (had a few other bits of work done at the same time).  We are in the California bay area, so everything is more expensive here. We did the sub-panel ourselves, as well as all the garage wiring.
> 
> Personally, I think it would be cleaner to run to a sub-panel, that way you can add separate breakers and runs for your large equipment so that they are properly sized. Keep in mind that if you are going with the #8, you will not be able to exceed 40A. If it were me, and I were planning on staying in the house for a while, I would go for a heavier conductor. That way, if you upgrade your main service panel, you can just upgrade the breakers, and the wire will already be sized correctly. Of course, that is going to depend on your situation; if the wire pull is short/easy, and you already have the #8, not much risk in going with a 40A circuit to serve your immediate needs.




A secondary consumer unit (fuse box) is a nice neat way, one big cable then brake it out local, less far to walk incase a mcb goes click 

stuart


----------



## Walt (Aug 12, 2013)

icore3user said:


> how old is your 100 amp panel?
> are you using full size breakers?
> who makes it ( Cutler Hammer, GE, etc.. )
> Most 100 amp panel ( depending on their size ) are 12/24 panels 12/20 or varaints... that is 12 full size breakers with space for up to
> ...



The panel is about 50 years old. It's a Wadsworth.

The circuit will be used to power a Monarch 10EE via a rotary phase converter. Not sure if that falls into the category of a piece of equipment that should have a dedicated feed. It would be nice to be able to power my new mill off of the same circuit. It has a 1.5 hp 220v motor listed as "9A".

http://www.machinetoolonline.com/PM-932M.html

 I guess I can get by without the compressor if need be. I'd like to get the lathe operational and money is a consideration.

Walt


----------



## Ulma Doctor (Aug 12, 2013)

Hi Walt,
2 seperate circuits on 1 breaker is a not recommended.
it might be easiest and cheapest to add a sub panel or go without a electric stove or clothes dryer.
i have disconnected both of the mentioned appliances at one time or another to get juice to the machines.
i even keep a long (35') male dryer plugged 240v single phase extension cord around, just in case i got to do some welding at a neighbors or a friend's house. it's the straight blades on one side 30A twist lock on the other. 
all my 220 welders and other equipment all have twist locks on em'!!


good luck!!
mike)


----------



## Walt (Aug 14, 2013)

DMS said:


> I have the type of breaker shown in the top picture of this link
> 
> http://www.structuretech1.com/2010/01/how-to-correct-double-tapped-circuit-breakers
> 
> ...



Thanks for the link. Looks like I could "pig tail" a second circuit in. Doubling up the lines at the breaker isn't an acceptable option according to your link.

Still not sure what a sub-panel does for me. Is it that I can size the breakers to each machine?

Walt


----------



## Walt (Aug 14, 2013)

Ulma Doctor said:


> Hi Walt,
> 2 seperate circuits on 1 breaker is a not recommended.
> it might be easiest and cheapest to add a sub panel or go without a electric stove or clothes dryer.
> i have disconnected both of the mentioned appliances at one time or another to get juice to the machines.
> ...



Hi Mike,

I have gas for the stove and dryer, so nothing to be gained there.

The shop has 2 110v lines to power lights and other machinery. Maybe I'd be better off combining those into a 220v feed to a sub-panel and powering the lights and 100v machinery from the new sub-panel? That would allow me to leave the existing 220v line to the compressor in the garage alone.

Lots to think about. I'm not sure the 40A 220v breaker I've got will do the job. Also the #8 cable I bought might not be enough either. Sigh.

Walt


----------

