OP
747driver
Veteran Member
Didn't think about the air hose to another out building !! Keep digging trenches !!
What size service wire for new workshop
- Thread starter 747driver
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Didn't think about the air hose to another out building !! Keep digging trenches !!
OP
747driver
Veteran Member
Chris you just threw out a answer that caught my attention. Just purchased a 'new to us' motorhome. Was thinking about a exterior box out to the rv cover, so as not to run the generator. The barn comes first though, then the rv !!
Nelstomlinson
New member
Here are a couple of thoughts:
Bury your second conduit as far as you can from the conduit with the power line. A foot of separation is good. You don't want to induce noise on the data lines in the second conduit.
Number 4 copper has a resistance of 0.29 Ohms per 1,000 feet. You will have 240 feet of copper (out and back), so that's 0.069 Ohms. If you pull 50A, your voltage drop will be 4.2V. That doesn't look like a problem to me. If you were to put in bigger breakers, you could go up to 85A to protect that conductor size (assuming it's rated for 75 degrees C), which would be almost 6V drop. That's about 5% drop, which is about as big as I would be comfortable with. Might as well put in an 85A breaker to feed the cable right now, and an 85A or smaller breaker in the subpanel. It won't change the cost enough to notice, and there is no point in handicapping yourself.
If you ever want to use 120A in the barn panel and 130A to feed it, you will have to go up to number 1 copper. That would give about a 4.6V drop at 120A, again acceptable.
Bury your second conduit as far as you can from the conduit with the power line. A foot of separation is good. You don't want to induce noise on the data lines in the second conduit.
Number 4 copper has a resistance of 0.29 Ohms per 1,000 feet. You will have 240 feet of copper (out and back), so that's 0.069 Ohms. If you pull 50A, your voltage drop will be 4.2V. That doesn't look like a problem to me. If you were to put in bigger breakers, you could go up to 85A to protect that conductor size (assuming it's rated for 75 degrees C), which would be almost 6V drop. That's about 5% drop, which is about as big as I would be comfortable with. Might as well put in an 85A breaker to feed the cable right now, and an 85A or smaller breaker in the subpanel. It won't change the cost enough to notice, and there is no point in handicapping yourself.
If you ever want to use 120A in the barn panel and 130A to feed it, you will have to go up to number 1 copper. That would give about a 4.6V drop at 120A, again acceptable.
ultrarunner
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Looked at a shop the other day and the feeders were double #2... had never seen it before and asked.
Was told the owner had a lot of Free #2 so the electrician doubled up on it and it passed.
Is doubling up acceptable nationwide?
Was told the owner had a lot of Free #2 so the electrician doubled up on it and it passed.
Is doubling up acceptable nationwide?
hr3
Veteran Member
1/0 is the smallest conductor you are supposed to parallel ...
Sawyer Rob
Super Member
I had another meter put on my shop, now it has a full 200 amp service, and it's really nice when I'm welding and the compressor starts... OR I'm running my dust collector, jointer and planer at the same time and need the table saw to make a quick cut!
Get the new meter and have full power out there!!
SR
Get the new meter and have full power out there!!
SR
ultrarunner
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Thanks for the information... explains why I had not seen this before.
Sysop
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I'm in the process of upgrading "the old family farm" and am having new 400A service ran to my new workshop. From there I'll break off 200A and send to the original panel that runs the houses, disconnecting the old service in the process. I'm doing it this way to get rid of my overhead lines and put them underground. Perhaps the same or similar could work for you...
grsthegreat
Super Star Member
Aluminum feeder wire is the norm in most states. Remember, all the wires the utilities use are aluminum. Todays alum wires are way more sophistacated than those used in the 1940's. Those wires caused the uproar. As long as the wires are used under lugs and with deox, there are no worries. Ive gone back into 10 year old panels to check how tight the connections are....theres no way to move the lug.
Personally, the smallest feeds i ever run to shops or large outbuildings would be a #2 aluminum. This would provide a true 100 amps out to 100 feet with minor voltage drop. When the distances get out to 300 feet, i can still get 70 amps with not much voltage drop.
There is absolutely nothing wrong with downsizing the breaker at the shop. That breaker ONLY PROTECTS THAT PANEL. the house breaker protects the wire. As long as the wire is large enuf to handle the load... No problem.
When i ran my barn i used copper wire only cause i got a great deal on wire. My shop and carriage barn were run in aluminum underground.
As a side note,..i NEVER go direct bury. If my customer insists on it, i decline the job. The most expensive part of new service is the excavation, so why do it twice if theres ever an issue down the line.
I usually try to talk my customers into going larger in service than they think they want. Some people have built 30x40 shops and only want a single 20 amp, 120 line installed... Thats nuts.
Personally, the smallest feeds i ever run to shops or large outbuildings would be a #2 aluminum. This would provide a true 100 amps out to 100 feet with minor voltage drop. When the distances get out to 300 feet, i can still get 70 amps with not much voltage drop.
There is absolutely nothing wrong with downsizing the breaker at the shop. That breaker ONLY PROTECTS THAT PANEL. the house breaker protects the wire. As long as the wire is large enuf to handle the load... No problem.
When i ran my barn i used copper wire only cause i got a great deal on wire. My shop and carriage barn were run in aluminum underground.
As a side note,..i NEVER go direct bury. If my customer insists on it, i decline the job. The most expensive part of new service is the excavation, so why do it twice if theres ever an issue down the line.
I usually try to talk my customers into going larger in service than they think they want. Some people have built 30x40 shops and only want a single 20 amp, 120 line installed... Thats nuts.
ultrarunner
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My Washington 400 amp circa 1978 is direct bury installed by the utility.
Three times in the last 7 years I have lost one leg... each time the utility has come out and made repair...
The last time I was told they will not continue making repairs and that I would have to upgrade... citing end of life.
This is my only experience with direct burial and surprised the Utility that was paid to furnish, install and maintain to their transformer is saying it will be my problem???
My home is the only home with underground because this is what the county required... all of the surrounding homes predate mine and have power poles...
Three times in the last 7 years I have lost one leg... each time the utility has come out and made repair...
The last time I was told they will not continue making repairs and that I would have to upgrade... citing end of life.
This is my only experience with direct burial and surprised the Utility that was paid to furnish, install and maintain to their transformer is saying it will be my problem???
My home is the only home with underground because this is what the county required... all of the surrounding homes predate mine and have power poles...