What size service wire for new workshop

747driver · May 9, 2015

I am running new electrical wire service for my barn from the house. The house is 200 amp service. The run to the barn is 120 ft. I have figured i will need #4 XHHW wire. This wire is made for running in conduit which i am doing, is more flexible also for pulling.

I have a 125 amp service panel at the barn. Does this #4 size wire work ? Will put a 60 amp breaker at the house and a 50 amp main breaker on the box at the barn ? I have a 220 tablesaw, 220 air compressor, 220 wood jointer as my big power draws.

Thanks

Chuck

MacLawn · May 9, 2015

I think I'd rather have barn on a separate meter. But, wha' do I know?

yelbike · May 9, 2015

Why a 50 amp in the burn and 60 at house. Should be the same size.

aczlan · May 9, 2015

yelbike said:
Why a 50 amp in the burn and 60 at house. Should be the same size.

Perhaps to avoid tripping the breaker in the house? Shorter walk to the barn/shop panelbox than to the house one.

Aaron Z

dstig1 · May 9, 2015

Voice of experience.... Save yourself the time and expense of doing it over later. Pull bigger wire now. I would pull enough to make a 200A subpanel, even if you don't use it to the fullest right now. Your power needs will only grow with time. Pull 2/0 copper or the alum equivalent (looks like 250 mcm, but don't quote me on that...).Later on you may find that you need more and want to upgrade your house service to accommodate that. If you pull big wire now, you will make your life easier later. If you (seriously) believe that you will not live here for the long term, then you will probably just want to do what you suggested.

My $0.02

mddorange · May 9, 2015

I agree with Dave as I have learned the hard way that what you think is fine now will not be enough later.

yelbike · May 9, 2015

dstig1 said:
Voice of experience.... Save yourself the time and expense of doing it over later. Pull bigger wire now. I would pull enough to make a 200A subpanel, even if you don't use it to the fullest right now. Your power needs will only grow with time. Pull 2/0 copper or the alum equivalent (looks like 250 mcm, but don't quote me on that...).Later on you may find that you need more and want to upgrade your house service to accommodate that. If you pull big wire now, you will make your life easier later. If you (seriously) believe that you will not live here for the long term, then you will probably just want to do what you suggested.

My $0.02

Put oversized conduit instead than pull the proper size wire you need now. If your needs change, you pull the existing cable out and replace it to your new needs. 2/0 cu is expensive for 120' if you'll never need it. Remember, only calculate the loads that will be used simultaneously.

hr3 · May 9, 2015

One important thing you didn't tell us is are you planning on running copper or alum. wire ????

Wire Size Calculator

outinthetalgrass · May 9, 2015

yelbike said:
Put oversized conduit instead than pull the proper size wire you need now. If your needs change, you pull the existing cable out and replace it to your new needs. 2/0 cu is expensive for 120' if you'll never need it. Remember, only calculate the loads that will be used simultaneously.

I'll go one step further, when placing conduit from house to barn, put in another smaller conduit line at the same time to have for later. (Cat6, phone, coax, or fiber) think security systems, remote control for lights, cable or satellite TV, networked cameras, or even a intercom system from house to barn.
I have trenches from the house to the barn 3 times now, the last time I put in 2" pvc conduit, so when I decide I need something else out there, I have room in the conduit (and a pull string) so I can get it out there without having to dig again. There may always be something new you want to add, that you weren't thinking of 4 years ago. More of the learning things the hard way.

gary49 · May 9, 2015

Agree that installing 2'' conduit is a good idea. #4 AL may be fine, depends on how much equipment runs simultaneously. I have an equipment shed fed with a 200' run of #4 AL. Biggest load is AC welder. Also have air compressor and lights. 60 amp breaker has never tripped in 10 years of use. The caveat is that it is almost always just one person doing anything in there. No need for copper in that conduit unless you have deep pockets and like spending it.