Feed wire sizing to my garage

magu

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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.
 
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.
 
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.
 
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.
 
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.
 
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
 
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.
 
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.
 
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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