What size wire do I need?

[snickers muncher]

Howdy folks. I'm replacing my parent's electrical in their barn. They have a 50 amp breaker in the house feeding the barn. The house is then connected to the barn through a service drop of maybe 80 feet. The cable then goes to an old fused disconnect switch which then feeds a small fuse box with only one fuse using 12/2.

I would like to keep the disconnect inside the barn so you don't have to go into the house to kill all the power. What size wire should I run from the disconnect to the new subpanel? Can I just use 6/3 romex since it'll only be a couple of feet @ 50 amps or do I need bigger?

Separate neutral and ground, two ground rods, etc. The goal is to have a subpanel with three circuits. One for lights, one for outlets, and a third to run a UF to power a shed about 15 feet away.

Thanks

 

[wyliesdiesels]

6/3 NM-b is fine for 50a

what size the wire in the overhead drop?

is it 3 or 4-wire?

 

[snickers muncher]

I think the overhead is 4, but it could be larger. I'm not there currently. It's only three wires. Two insulated hots and the bare neutral.

The previous owner had a welder tied into the disconnect.

 

[Syberia]

6/3 will work for 50a.

 

[alfredeneuman]

It's only three wires. Two insulated hots and the bare neutral..

3 wire feeders are no longer acceptable
You need to have a ground wire all the way in addition to the 2 hots and the neutral.

 

[rburke65]

But must the original poster change to 4 wires from house to barn? I wouldn’t think so

 

[snickers muncher]

Thanks guys. I grabbed some 6/3 and clamps from the hardware store. I installed the panel and ran the 6/3, but didn't have time to install the ground yet.

I knew new construction required 4, but thought old work 3 was still acceptable.

 

[alfredeneuman]

I knew new construction required 4, but thought old work 3 was still acceptable.

3 wire feeds are alright but cannot be modified.
The Code changed with the 2008 Edition

 

[wyliesdiesels]

I think the overhead is 4, but it could be larger. I'm not there currently. It's only three wires. Two insulated hots and the bare neutral.

The previous owner had a welder tied into the disconnect.

you need to change it to 4-wire as the bare neutral is not kosher.

 

[snickers muncher]

you need to change it to 4-wire as the bare neutral is not kosher.

Well poop. This project just got a lot more expensive.

 

[Bert_]

They let us leave 3 wire feeds in a situation like that.

 

[snickers muncher]

I'll discuss it with the inspector. He just came home after 100 days in the hospital with covid and lost his wife to it while hospitalized. He's a great guy who could often be found hanging out and giving advise in the same mom and pop hardware where I bought the wire and clamps. My folks know him well and I'll have them give him a call.

 

[u2slow]

@snickers I take offence to Code when they allow something for decades, and then they forbid it... but in the same breath you're allowed to keep using it, unmodified.

By allowing the continued use, it has to be safe enough. Home insurance toes the same line. That's why I say the only time you need to strictly follow current Code is to satisfy a permit.

 

[wyliesdiesels]

They let us leave 3 wire feeds in a situation like that.

with a bare neutral?

 

[PCustoms]

with a bare neutral?

Doesn't every arial feed have a bare neutral?

 

[wyliesdiesels]

Doesn't every arial feed have a bare neutral?

most do however this isnt on the line side of a main breaker.

this is a subpanel. having a bare neutral on a branch feeder creates a potential for shock hazard

 

[u2slow]

most do however this isnt on the line side of a main breaker.

this is a subpanel. having a bare neutral on a branch feeder creates a potential for shock hazard

Its the same potential shock hazard for triplex whether on the line or load side of the main.

As a homeowner... I would put on my 80's-90's NEC hat, replace the disconnect with a panel, and add a ground plate (or rods). Done.

 

[Bert_]

Even without considering the three wire feed I don't see the issue with a bare neutral in overhead. It's required to be high enough and out of reach.

Add to that fact this is three wire so it's already bonded on the end. Keeping it at ground potential is why you put in ground rods.