alexpops
Platinum Member
Not to highjack the thread, but for the guys that do (have done) this for a living, when calculating distance for voltage drop, is it linear distance from source panel, or do you double that for the length of the circuit?
Welder / Wiring for Small Garage
- Thread starter dieselscout80
- Start date
I’m working on the same problem. I have 100 A service to the barn. I figure I will put in a 50A breaker and run 90C THHN (what Home Depot sells) in 3/4” EMT. IIRC 8 ga is ok for 50A on low duty cycle. I’m guessing that is cheaper than 6 ga Romex. Only question now is whether to run a neutral and bigger wire so I can say “Tesla ready” when I sell the place. 
I just wired an outdoor welder outlet as a favor to my neighbor. 50 A breaker, 6 ga THHN in 3/4” EMT w/ liquidtight fittings. But only 3’ from the panel. Stuffing 6 ga wire and the 6-50R recepticle into a standard depth outdoor double gang box=impossible, so I had to get an extra depth outdoor box
I just wired an outdoor welder outlet as a favor to my neighbor. 50 A breaker, 6 ga THHN in 3/4” EMT w/ liquidtight fittings. But only 3’ from the panel. Stuffing 6 ga wire and the 6-50R recepticle into a standard depth outdoor double gang box=impossible, so I had to get an extra depth outdoor box
Topzide
Gold Member
8 ga is a 45 amp wire not 50 amp. I run an ac/dc tombstone on a 30 amp circuit with no issues and have done so for 20 years. Put a 40 amp breaker on that 8 ga and call it good.
I was going by the Cerrowire chart.
I’d use 6 ga in Romex, but if I’m reading the chart right, I could use 8ga 90C THHN in EMT up to 55 A. Wouldn’t run a continuous load like a Tesla charger off 8ga, though
I’d use 6 ga in Romex, but if I’m reading the chart right, I could use 8ga 90C THHN in EMT up to 55 A. Wouldn’t run a continuous load like a Tesla charger off 8ga, though
Gord Baker
Gold Member
You might consider a 200 Amp service to the Barn.
grsthegreat
Super Star Member
You dont know what your talking about. Each leg carries 30 amp.
nothing like the internet to pass on wrong info.
Last edited:
CliffordK
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39? Typo?
CliffordK
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It depends on your charging circuit. A Tesla is off in its own world.
My EV (Not a Tesla) uses a basic J1772 connector. At 110V, it pulls about 12 Amps or so, and takes forever to charge.
I should be able to upgrade to 220V at 30A or so which would charge at 4x to 5x the speed of charging at 110V which would be sufficient for my needs.
It shouldn't be a problem charging off of 8AWG.
However, if one is future proofing the circuit, then the more power the better. I'm seeing 48A chargers being common, and some home chargers pulling as much as 80A, 220V. WHEW!!!
MAX-24-Dean
Veteran Member
Copied and pasted from the bottom of the chart in the link.
WARNING! Installation of electrical wire can be hazardous if done improperly, and can result in personal injury or property damage.
For safe wiring practices, consult the National Electrical Code ®, your local building inspector, or a qualified electrician.
#8 THHN is only rated for the ampacity in the 60°C column due to a code requirement in article 110 of the NEC. It would be good for ampacity of up to 40 amps according to the ampacity table in the attachment.
Be safe!
Thanks. I have an older copy of the NEC. Be interested in the 60C citation