Want to add 230V outlets to my barn

LeRoi · Nov 16, 2005

My barn is wired as a sub to my main panel in the basement. I have 100A service coming in the house. There are 2 50A breakers tied together for the main cutoff. The breaker for the subpanel in the barn is tied into the main with the same (2 50A breakers).

 

When you say two 50 amp breakers are you talking about a double pole breaker that takes up two spaces in the panel or two double pole breakes that take up four spaces in the panel?
If your barn breaker takes up two spaces then you have a double pole 50 amp circuit breaker feeding 240 volts to your barn. The wire size should be at least #8 AWG copper, but could be larger depending on the distance the barn is from the house.
You can wire in a 50 amp outlet and start welding. I doubt that you will ever have a problem because for hobby welding you'll never set your machine up to pull full current long enough to trip the circuit breaker. You can overload them for a while without tripping them.
hth
Leroy

HomeBrew2 · Nov 16, 2005

So, I answered your question but, I'm really curious about your setup ... added to my confusion.
If I take your post literally, you have a 100 amp service to your home. From my, non-professional, experience, that means a 100 amp / 115 volt service (100 x 115 = 11500 watts) ... very common ... many years ago. I'm wondering what electric loads you have in your house and how a 50 amp / 230 volt (50 x 230 = 11500 watts) load in your barn will impact your home ... water well pump, A/C, range, heaters. Inquiring minds want to know /forums/images/graemlins/wink.gif
Cheers!

mwood · Nov 16, 2005

Okay. I see I'm confusing people here.

I'll try to get some pictures in the morning, but for now, here is my best explanation.

My main panel in my house has a sticker on the inside of the door which says 100 amp. It was placed there by the power company I believe when they connected the main. From what I can tell, that means I have 100A main service.

At the top of this panel, there are two breakers (I believe double pole as they take up 4 spaces) with their switches tied together with a bar. It is labeled "Main" and each breaker is a 50 A. This makes sense with the 100 A service.

Further down the panel, there are again two breakers tied together with a bar. They look exactly like my main breakers (again, taking up I believe 4 spaces). They are both 50 A. These are labeled "Barn".

From this main panel, there is 1.5 - 2 inch conduit running up to the ceiling and down the opposite wall in my basement. At the point where the conduit exits the house, there is a small (2 X 6 in) access point. Removing this cover shows 3 quite thick wires. Not sure if the copper itself is thick or just the insulation.

Now to the barn. The same type of conduit comes out of the ground on the inside of the barn and into a sub panel. The main of this subpanel is a single 40 A breaker (if I remember correctly -- I will verify this in the morning).

My guess (to be confirmed in the morning when I take the cover off both panels) is that the three wires are two hot and one ground. I believe there are double pole breakers all the way to the barn which would mean I have the capacity for 100A / 220 V in the barn. This would be ideal.

The guy who build this house made sure that everything was overbuilt. I would think that he probably did this right too, but wanted the collective TBN brain to re-assure me so I don't start any electrical fires or cause serious damage to my house wiring. (The barn is simple and would be easy to re-wire. I think there are all of 3 outlets and 4 lights).

Thanks again and I'll post pictures to hopefully make it clearer!

Mark

RonL · Nov 16, 2005

WOW!

I think you ought to hire an electrician. From your initial post and the answers you got here, that might be the most sensible thing to do. I don't mean to sound condescending, but the questions and answers are a little scary.

RonL

rambler · Nov 16, 2005

Also mention the distance between your house & barn. Distance is very important when considering wire size.

You cannot assume your wires carry any more than 40 amps. I would not think they can handle 100! I'm not sure why you are assuming that. If a 50 amp was on the feed end, and a 40 amp on the far end, you can olny assume you are allowed 40-50 amps. People rarely over-size the wires.

I had my place rewired, the whole farm had 60 amp service - for everything. That was a pair of cartridge fueses. From that main disconnect, the shop had 40 amp 220, the house had 40 amp 220, and most all the other buidlings had 110 20 amp - couple 220 20 amp. All on 8 ga copper wires - wasn't right.

Anyhow, you say you have a 100 amp box, but you have a 50 amp curcut breaker. This confuses me. It sounds like you have 100 amps into the main box, and a pair of 50 amps leading from it - one for the house, and one for the shed? Nowhere do you have a 100 amp breaker, nor the wires to support 100 amps? As I see it.

--->Paul

mwood · Nov 16, 2005

@RonL: I'm not sure why you are so scared. I think that people are giving some good advice, and I just might hire an electrician. I'd just rather know all I can about this regardless. I like to know how things work and would really like to understand this better.

@Rambler:
If I have two 50A double pole breakers tied in parallel, that makes 100A. (Only if there were in series would I have a limit of 50 A). Therefore, I at least have 100A service for my main panel. Any draw over that and my main will trip. If the same is being used for the barn out of the main panel, I could in theory use the full 100 A in my barn. This would create a condition where my well pump, furnace or other household things would cause the main to trip.

In actuality, I should probably limit my use to the barn to something like 60 A. There is very little chance of needing more and that would ensure that the necessary household items wouldn't blow the main.

However, and this is the main point, this is all reliant on the fact that the wiring in the conduit is able to carry 60 A.

@Everyone:
Thanks so much for the help so far. I promise that I won't do anything stupid! /forums/images/graemlins/tongue.gif

Edit: Also, I should mention that the distance from the house to the barn is around 250 ft.

JustGary · Nov 17, 2005

mudcat -

I said, ( If I remember right, I used #6 Aluminum for the ~50 foot run from my house to my shop for 100 Amp service. - ) and you said, ( I hope not. )

Gheeeze, you're right! My rememberer isn't right. It's probably around #1 or so. I looked tonight, and each cable is a little smaller than my little finger. Thanks for keeping me from passing along some real bad advice!

Check the table of load capacities before you wire anything. That URL has a handy voltage drop calculator at the bottom, too.

- Just Gary

mwood · Nov 17, 2005

@JustGary - I was kinda wondering about that.

Learning lots here. I've read all I can find on this sort of thing and am starting to feel like I actually have a clue (or at least half a clue /forums/images/graemlins/wink.gif) as to what to be looking for!

Thanks to all for your help!

Mark

BobReeves · Nov 17, 2005

With you last description the house end sounds like it should be OK and you do have 220 running to the barn. I am still wondring about the single 40 amp breaker in the barn.

You may just have a single phase disconnect box in the barn which wouldn't allow you to add a double breaker for the welder.

If I could see a picture of the barn pannel with the cover off I could tell you exactly what you need to do.

ericbx · Nov 17, 2005

When I wired mine I used #8 thhn which will handle 55amps but since I have a 130' run I only used a 30amp breaker at my main panel with a sub panel in the pole barn. I ran two hot's and a neutrel from the main panel and installed two grounding rods at the barn.

also I dont have a main breaker at my sub panel in the barn just at my main. I used a 30amp breaker instead of a 40amp because of my 130 ft run to the barn. /forums/images/graemlins/grin.gif