Selecting wire size to new garage

[Overhaulin63]

I've ready several posts on this site but it seems everybody wants something a little different so I thought I would post for my own project.

My garage is about 160 ft. from my house or power source. I have 200 amp service coming into the house but I am not sure how to go about determining what wire size I need for the garage. I have a boiler for radiant heat, Bridgeport /3 phase converter, welder, lathe and other similar shop equipment along with lighting and a Bendpak lift.

Any thoughts on wire size for this distance? I always try to go with a little more than I need so I've got room for future, unknown, expansion. I hate doing things twice.

Thanks in advance for any help!

 

[jav]

There's 2 schools of thought.

1) determine how many amps you "really" need. IE. determine what your greatest electrical demand would be at any point in time and size for that. My guess is if it's just you and one other person using the garage, 75 amps might be enough so 4 AWG- - (lights (15A?) plus heat (20A?) plus 2 pieces of equipment @ 20A ea) . Without looking it up, I think 6 AWG THHN will go to 75A but your run length requires up sizing to 4 awg- I think?

2) Design in some spare capacity for future expansion - then ampacity is your choice and will determine conductor size.

 

[Norcal]

There are NO 75 ampere circuit breakers, you may have a 70A, or a 80A.

 

[dw1]

I've ready several posts on this site but it seems everybody wants something a little different so I thought I would post for my own project.

My garage is about 160 ft. from my house or power source. I have 200 amp service coming into the house but I am not sure how to go about determining what wire size I need for the garage. I have a boiler for radiant heat, Bridgeport /3 phase converter, welder, lathe and other similar shop equipment along with lighting and a Bendpak lift.

Any thoughts on wire size for this distance? I always try to go with a little more than I need so I've got room for future, unknown, expansion. I hate doing things twice.

Thanks in advance for any help!

If you used #2 alum MHF (4 wires) at 160' it is good for 75 amps, as Norcal stated above, put a 70 amp breaker in your house panel feeding this. A load calc would be good. Don't forget 2 ground rods at garage panel, separate grounds and neutrals in garage panel.

 

[JECulver]

#4 wire on a 60 amp breaker. If you will only be using one piece of equipment at a time.
If your welder is large or you plan on using more than one piece of equipment at a time go with a 100 amp breaker and #2 wire

 

[pattenp]

#4 wire on a 60 amp breaker. If you will only be using one piece of equipment at a time.
If your welder is large or you plan on using more than one piece of equipment at a time go with a 100 amp breaker and #2 wire

Are you talking about copper or aluminum wire?

 

[Overhaulin63]

I am guessing copper.

 

[matt_i]

Can you define "welder" more clearly? A 120vac minimig vs a 350A transformer-tig welder are vastly different animals. Another way to look at it is the welder is likely your biggest amp draw, so that's very important in sizing the circuit.

If a low draw welder you're probably in the 60A range, if something more serious I'd push for a 90/100A feed.

Also....I'm assuming your boiler is fossil-fueled, the electricity is merely for running circulation pumps and controls...

 

[wyliesdiesels]

If u wanted to do a 100a feeder u could use #1 al with a #6 al egc/ground.

 

[Overhaulin63]

275 Lincoln Tig

 

[milner351]

I built a similar set up about 15 years ago.
I put new 200amp underground service to the house - a new 200amp panel in the house.
I used 1 100amp breaker in the house to feed the barn, and put a 100amp panel in the barn.

I do not have a bridgeport (unfortunately) but I do have a 7.5HP air compressor, Whip 2 post lift, Synchrowave 200 ac/dc tig/arc, and 180 auto set mig, a plasma cutter, and the typical electric tools, roughly 16 4ft shop lights, and a waste oil furnace that requires electric and compressed air.

I've never had an electrical supply issue.

The cable from the house to the barn was already there
(I replaced the panels but kept the wires)
I did install a new ground rod (2 at the house, 1 at the barn)
I cable from house to barn is copper - I think it's #4 but it may be #6 - I know it was a snug fit on the 100amp break in the house - the run is roughly 100ft.

 

[alfredeneuman]

Milner
#4 copper on a 100 Amp breaker is against the NEC. The minimum size is a #3 for 100 Amp
There's an exception for services, but it doesn't extend to feeds for subpanels like in your case.

#6 is even less suitable.