What size wiring and conduit do I need?

I am wiring a 100 amp service to an external shed from the house 200 amp service. I would like some help on the size of wire and number of each size as I believe the ground does not have to be the same size as the Hots and neutral. Also if you could help with the size of the conduit required it would be great. I plan on using copper wire.

Also does the distance matter. I was thinking of putting the shed between 120 and 300 ft away from the house.

Thanks for all of your help!!

Michael .C

Reply to
montanabucks
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I take it you're not planning to get a permit for this, and you don't care if you have a house fire and your insurance company discovers a major electrical modification which was never permitted or inspected and they duly refuse to pay for your damages.

If you can afford to take on a risk like that, you might consider spending a few bucks on a licensed electrician. Pulling a 100 amp subpanel isn't the same as hooking up a hot tub or welder circuit.

On the other hand, maybe you live in rural Montana (going from your email handle) and really permitting and inspection is no big deal. Then I suggest you go to a local electrical supply (wherever you plan to buy your conduit and wire) and buy an inexpensive little book called "Ugly's Electrical References". It is an excellent reference, and you will use it often, as I do. I believe this information can also be found in "Pocket Ref", a little black book offered for sale next to the register at many hardware stores, published by Sequoia Publishing.

Grant Erwin Kirkland, Washington

Reply to
Grant Erwin

This is one of those questions that if you have to ask, you shouldn't do it with out professional help. You may find that if you do all the grunt work, a licensed electrician will do the final hookup for very moderate money.

As for wire size, the first thing to ask is: what code you plan to wire it to? If you pull a permit, the inspector will have minimum wire sizes. If you don't need a permit, pick up a copy of the NEC so you at least have something to work from.

100 amp and 300 feet is going to call for some pretty sturdy wire. With the current cost of copper, you may need a second mortgage to pay for it. Consider aluminum wire. Yes, you will need to go a size larger for 300 feet versus 120 to keep the voltage drop under control.

Most wire > I am wiring a 100 amp service to an external shed from the house 200

Reply to
RoyJ

"montanabucks" wrote in news: snipped-for-privacy@i42g2000cwa.googlegroups.com:

At that distance, you would be much cheaper to just install a separate service entrance for the shed.

Reply to
Anthony

Per table 310.16 of the NEC a minimum cable of 1/0 for direct burial cable or 3 AWG for cable in conduit is needed to carry 100 amps. That is the minimum size. You will need to increase the cable size as the run gets longer and you can find this out with a "voltage drop calculator" Code is

5%, better is towards 3% drop. (Here's one -
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Note - 1/2 total circuit means one way length) Call the electrical inspector as I've had to provide the ground at the panel and did not need a ground cable back to the main panel.

Conduit is sized by taking the size of the total cables and having that volume be no more than 40% of the interior conduit volume. Plus no more than two 90 degree bends. Advise to oversize the conduit as pulling conductors in a conduit just big enough can be a pain. Conduit gets buried at least 18" down or you can skip the conduit and use direct burial cable at least 24".

Steve.

Reply to
SteveF

Reply to
RoyJ

RoyJ wrote in news:dKgLg.3470$v% snipped-for-privacy@newsread1.news.pas.earthlink.net:

It won't matter, When he gets the wire price, sticker shock will have him putting in a separate service at the shed.

Per encorewire *distributor* price sheet (not retail) dated Sept. 6,

2006, 1000 Ft of 1/0 goes for between $4862 and $6599 depending on type. If, because of distance he has to step up to 2/0, then it's between $5700 and $8084 / 1000 ft.

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A meter base, weatherhead, conduit and 45 ft of 2/0 is going to be a

*lot* cheaper.
Reply to
Anthony

I gave him the values for copper since the poster said "I plan on using copper wire".

The type of insulation required is based on whether it is direct burial, conduit or open raceway. Unless he is going to build a covered walkway between the house and shed it doesn't look like open raceway would be an option.

But to address the point raised, 310-16 values for copper of 1/0 is for TW or UF and 3 AWG is for RHW, THHW, THW, THWH, XHHN, USE and ZW.

In any case, the length of conductors and the voltage drop are probably going to be the determining factors.

Steve.

Reply to
SteveF

Reply to
RoyJ

Uh, it can be. Of course, with a totally detached building you can take some shortcuts that make it a bit cheaper, but you sure can do it like any other 100amp circuit.

I'll have to check it out. I normally use the NEC or NEC Handbook (same information plus some of the background) but it is awfully verbose at times...

I have that one and highly recommend it.

sdb

Reply to
sylvan butler

I wouldn't.

Yup. And aluminum is a lot cheaper in those sizes, and has been even before copper went 5x.

And the hookup fee? And the minimum monthly charge? And the extra charge for their wire to run across your property? Oh, and it requires another pole or trenching?

What utility is going to provide a 2nd hookup to one property for free? Your out-of-pocket getting the service entrance ready is quite irrelevant to the total cost.

sdb

Reply to
sylvan butler

sylvan butler wrote in news:slrnefsbgp.hop.ZsdbUse1+noZs snipped-for-privacy@sdba64.internal:

Well, I don't know about where the OP is at, but here (southeast) it'll cost $45 for the inspection and $50 for the deposit if there is no electric heat, $150 if there is electric heat. The hook-up is free, provided you don't have to have another pole. At the minimum of $15 a month, it would take 22 years to make up $4000 (Figuring with the min price of wire at the $4862, and assuming you spent all $862 for service install, inspection and deposit).

Reply to
Anthony

Sounds like a heck of a deal. I've never seen a 2nd hookup anywhere close to that cheap.

sdb

Reply to
sylvan butler

I'm not clear from your post whether you do realize that the /0 matters (is wire gauge 0000, abbreviated as 4/0), and the copper is absurdly more expensive than the AL, or that you don't, and think they are the same size for the same price...

#4 is 204 mils diameter.

#4/0 is 460 mils diameter.

In cross sectional area, 4/0 is 5 times larger than #4.

Reply to
Ecnerwal

Reply to
RoyJ

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