Can you run a 100 amp sub panel off of a 200 amp main panel? In the past I ran 60 amp panels?
How do you determine the size of a sub-panel needed for a barn? Is there any code on panel size?
Also what size UF wire would you run? Does it need to be in conduit? In CU and AL? Thanks
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In the last week there was one or more threads that answered at least 1/2 of your questions.
Somebody hand off my grumpy batton to you today Bill?;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
No, thanks. I have my own.But I did give a good serious answer.And it can't be answered as it is written. He asks if he can 100 amp sub-panel.Then he asks how much of a service that he needs for the barn.Then the size of the wire. But how can you side the wire without knowing the load?Then I am doing battle with woodturner9 that seems to be quoting from the SCC. Slavic Candle Code.
What a guy, battling on two fronts. (;-)
remember I am not an electrician, but I observe what does happen on my jopbs and my guy is pretty particular about right.
We've had several 100 subpanels.
Size of wire depends on length of run. #6 probably
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A 100A subpanel requires #3 copper.
You do have to allow for line drop at the rates in the chart, right? I thought once you are past a certain distance, the wire needs to be supersized.
Upsizing certainly would not hurt - especially if you think you will be running it at full capacity for extended periods of time. #2 Cu has a 115A capacity & would certainly reduce the voltage drop.
I was mainly replying before because #6 was suggested which wouldn't be nearly enough (the NEC requires #4 for 100A service entrance & #3 for 100A branch feeder lines.)
I'm not trying to argue, just clarifying in my mind.I recall a 'disussion out in the driveway of a place we did bewteen the house eletrician and the poweer company rep deiding between the two of them what size wire to lay in underground. I didn't care, as lond as it was adequate and it got done.But I goota go check another sub-panel from years ago now. I'm almost ccertin it was fed with six
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What if it is 300' away?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
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Rebuilding my home in Cypress, CA
Also a CRX fanatic!
so what does your copy say?;)We need to help Bill out here!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
OK, this is for Mr. smartypants Piffen, who believes everyone should be an expert with a hammer and you should hang pictures with screws - MY GOSH THAT IS SO WRONG! :)...
Can you run a 100 amp sub panel off of a 200 amp main panel?
Yes. You just need a 100 amp breaker for that circuit to the subpanel.
In the past I ran 60 amp panels?
Yes you did. I've been following you around for years now and can conclusivly say you have installed at least one 60 amp panel. I've got a picture of you unboxing one around here somewhere.
How do you determine the size of a sub-panel needed for a barn?
You determine the size based on what devices you intened to run, and how many devices will likely be running concurrently. Are you running a table saw with the lights on and an electric heater? That's a pretty light load. Are you running hundreds of high watt grow lamps 24 hours a day with hydroponic equipment too? That's a much bigger load. The book will help you figure out what you need with real equasions too.
Is there any code on panel size?
There is code on everything, but the codes you are looking for are based on the amount of current you will be drawing through it. See the above answer.
Also what size UF wire would you run?
The table I see calls for 1ga. copper or 1/0 aluminumn, with an 8ga. ground conductor. If you can get this in UF romex, there are specific ways it should be laid. Get the book for the illustration.
P.S. There are a few people here who believe Al wire = fire. Just passing that on.
Does it need to be in conduit?
Yes and No. Get the book for the illustration.
In CU and AL?
There are a few people here who believe Al wire = fire. Just passing that on.
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
I would just add that the cable from the main panel may have to be upsized depending upon distance from house to barn to keep voltage drop under control.Steve.Who has a 32 year old barn wired by an idiot who ran a 12 AWG off a 20 amp breaker 290 feet to a 60 amp panel.
Edited 11/1/2006 7:03 pm ET by SteveFFF
Yep, there are all sorts of fine print things - those are included in the book too... which is why I recomended he buy it.
At this rate I'll get banned by Taunton for dishing out their books for free!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Actually it gives out much of it for free.http://www.codecheck.com/pg00cover.htm
On the AL thing - again, I don't really know what I'm talking about on this one, but if you can serve out screw advice, I can pay lip service to electrons until an electrician comes along - or is this kind of thing sort of like wheere we refuse to give out structural info because we don't have all the required info?Anyway, back to my thought on AL. On a fairly recent job, the electrician told me that for as long a run as we were considering underground, the wire size for AL needed to be larger than for copper. of courrse, it was still cheaper.AL is outlawed for some residential uses inside now, but I think that is for recepticle and switch locations, not heavy feeds. The reasoniong is this -as I understand it - the AL will expand and contract more than CU wiring and can loosen the connection over time with that much movement. That means a poorer connection which means more resistance and greater heat buildup which can melt the wire and cause a short and/or fire in the wall.But he should buy the book, I agree.Whatcha screw today? I bet it was well screwn;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
"screwn"... I think I have a new word in my vocabulary!Rebuilding my home in Cypress, CA
Also a CRX fanatic!
And I bet you will get your money's worth out of it!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
And how much insulation had melted off it?
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
None that I've found in either panel. The first time I plugged in my circular saw and listened to the motor struggling I told my wife not to use anything but the lights and I cart everything to the house that needs to be built. Once my new shop is finished (half way between) I'll probably run a new line to the barn.At least it's on a 20 amp breaker and not a 60!Steve.
"Steve.Who has a 32 year old barn wired by an idiot who ran a 12 AWG off a 20 amp breaker 290 feet to a 60 amp panel."Have you dug up the splice yet ?
Get over it....... The angry going eat you up. ~Brownbagg '06
No splices. If there was I'm sure the line would have shorted by now from being carefully sealed with duct tape.I also discovered on Saturday while installing the ground for the new house main panel that he was a little confused on one of the NEC specs. The NEC says to bury the wire 2 FEET down and he thought it was 2 INCHES with leaves being a code-approved substitute for dirt.Like Norm Abrams and Tom Silva say, "They don't make 'em like they used to. And it's a darn good thing."Steve.
Edited 11/2/2006 8:01 am ET by SteveFFF
I do own the book. I was too lazy to look.Page 17 says 3 uf goes to 110 amp but the barn is 150 feet from the house panel so a 3% line drop every 90'?The service is going to run a full size compressor, 3hp unisaw; 2hp woodsucker and lights at the same time.I just figured be save and go 100amp. Thanks
Can you run a 100 amp sub panel off of a 200 amp main panel?
Yes. You just need a 100 amp breaker for that circuit to the subpanel.
Not necessarily. You may need to use something other than a 100A breaker.
That was excellent. You are my new Breaktime superhero
Tom
You have the right to an electrician. Anything you say can and will be used against you by an electrical inspector. If you cannot afford an electrician one will not be appointed for you (sorry, this is not TV).
Seriously, dig your trench and have an electrician install the feeder and the subpanel. From there it may be possible to DIY the majority of your branch circuits.
Something like this I will do myself. I have run a few sub panels and I do not energize until the inspector approves. Everyone know there limits, I will not do a service because it would be a stretch. I have hired several pros over the years and thank god for the inspectors because everyone makes mistakes.
Examples of mistake Pro have made while I GCed....
20amp breaker 14g wire?
Neutral and ground bonded in sub?
40amp draw on 20amp circuit - wrong outlet?
Wires crossing perpendicular in HVAC ducts common?
Well, do it yourself then. But from your post it seems you don't know how to size the panel, whether or not there's adequate service, what size and type of conductors to run, and how to protect them. There are other relevant questions you didn't ask.
Before I answer your questions, I think your job has enough variations to it that you really ought to have an electrician look over the jobsite.
"How much power" depends upon your uses, and the size of the building. Have an electrician perform a "load calculation" for you.
There is no problem in running a 100 amp panel from a 200 amp panel; however, it is possible that adding the barn will over-tax your service from the PoCo. The electrician will consider this when he does the load calculation.
I strongly advise against the use of UF. While technically allowed by the code, it is a method that does not lend itself to easy repair or upgrading. Nor is it ever a good idea to run UF in pipe. (Doing so is hard work, and negates many of the advantages of pipe).
Rather, I suggest running big, heavy pipe (2" or 2 1/2" Sched 80 PVC, with RMC (steel) for the elbows and parts coming up out of the ground. Bury it deep, with a generous bedding of sand or gravel. (minimum 24" down to top of pipe, 2" sand /gravel under and over the pipe). (Don't forget the warning taps 12" down!).
Wire size, as well as the size of the breaker feeding the panel, will be determined by the load calculation. Since you've run a big pipe, it is no problem to run small wires today- and upgrade later when you need to.
(Another suggestion: Run a second pipe alongside the first one, for pulling phone cables, etc., at a later date).
Copper is the only wire material I would consider. Maybe I'm just old fashioned.
Two points to also consider: you will probably need an outside disconnect mounted on the barn, and you will certainly need a ground rod- in addition to the ground wire back to the main panel.
Again, your local Sparky will be able to suggest alternatives, and modifications, as local conditions mandate.
Everything here has been pretty well covered. Remember to put in a separate ground rod for a new sub and keep it separate from the neutral. Reno and Brown's suggestions were good about the shut off and extra pipe if you're going to dig. If you're doing it yourself, do not do this without an inspection.
It is doubtful that sizing your panel will be beneficial.
I would run conduit large enough for 100amp wires but put in 60amp breaker and wires. It is much cheaper that way. 60amp @240v is a lot of power to consume.
"It is doubtful that sizing your panel will be beneficial."So grapping any panel that is available, whether it is 30 amps or 400 amps, would work just as well?