Electrical question

The ONE thing I know. Do what the inspector says. You need a friend here.

Karl

What's the load?

It is a 100 amp sub panel in the detached garage. It will be ran 210 feet to my current attached garage.

Same exact measurements for me. My electrician said #3 copper with #6 bare ground or aluminum 2/0 direct bury. However, aluminum 2/0 direct bury was $350 for 200', and the same length for 3 lines of copper #3 and #6 was $880. Copper cheaper than aluminum? I don't think so.

Steve

The handbook says: For a 16 amp 110 V circuit running 200 feet you should use #4 copper for a 2% voltage drop. At 16 amps 220 V you should use #6. This should please the pickiest of inspectors.

Bob Swinney

I finally called the inspector and got a different answer than he had told me previosuly. Once he told me #4 copper with a # 6 ground and another time he told me #3 copper with a #6 ground.

He said I cant use the 2-2-4-6 wire the local supply house is tryign to sell me. He said aluminum would have to be #1 if in conduit and 1/0 if direct buriable. He said copper would be cheaper.

I dont want to tick the guy off but what should I do at this point?

To meet code, the sub panel would have to be fed with wire sufficient to carry the entire rated load of the sub panel. That is why such heavy wire is called for.

Bob Swinney

Bob Swinney

I finally called the inspector and got a different answer than he had told me previosuly. Once he told me #4 copper with a # 6 ground and another time he told me #3 copper with a #6 ground.

He said I cant use the 2-2-4-6 wire the local supply house is tryign to sell me. He said aluminum would have to be #1 if in conduit and 1/0 if direct buriable. He said copper would be cheaper.

I dont want to tick the guy off but what should I do at this point?

Is that 360 dollars for 3 strands of wire? What is the difference between 1/0 and 2/0? I assume 1/0 is bigger. He told me if I go direct burial I would have to use 1/0.

Is that 360 dollars for 3 strands of wire? What is the difference between 1/0 and 2/0? I assume 1/0 is bigger. He told me if I go direct burial I would have to use 1/0.

That would be three strands plus a ground in a direct bury enclosure 2/0 size. I'm not totally sure of this, so the best thing is to ask your electrician. Maybe someone here will know.

Steve

It is a 100 amp sub panel in the detached garage. It will be ran 210 feet to my current attached garage.

************************************************ Do you need that much? Can you use a smaller sub? What do you want to power? Big compressor? Welder? Time machine? I assume 240 V. AL is always cheaper!

On Wed, 28 Oct 2009 10:35:51 -0400, the infamous "Buerste" scrawled the following:

Where's the load? Between stryped's ears. PDFTFT.

How many amps will the breaker be rated at that feeds this panel from the main panel? That is the number that maters in the calculations.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Stryped

One thing that has been forgotten by some of us here, me included, is that the CB in the panel feeding your proposed subpanel has to be sized to protect the wire to the subpanel. One is not allowed by code to use an X amp circuit breaker and feed a wire of less rating. Turnabout is OK under most circumstances.

Copper will be more expensive but certainly not 3X.

100 amp service will require #1 if in conduit or direct burial. Has to do with heat. One or two sizes larger for 200+ feet because of voltage drop.

And all this discusion is based on 220 single phase. 2 hots, a neutral and a ground. Conduit and/or shield, if any, is not allowed as a ground. There are no current or voltage ratings that I am aware for conduit or ground. They serve a different purpose. Use of these creates ground loops.

Bob AZ

the difference is the diameter and current rating at the same temperature.

1/0 is 0 gauge, one size up from 1 guage.

2/0 is 00 gauge, one size up from 0 guage.

is a wire chart for copper wire.

is a chart for aluminum wire.

main panel? That

100 amps

Yup. My home has a 100 amp service. Back when copper was fairly cheap, I ran #2 copper out to the garage in case I upgraded my home's service and also needed more capacity out in the garage.

Currently the garage's 100A sub panel is fed from a 60A breaker in my main panel that protects the wire with room to grow a bit.

Now there is a rule that you want faults to be interupted as close to the fault as possible. The 100A breaker in the sub panel seems to violate that rule but it seems to be a common practice to feed a bigger breaker in this case from a smaller one.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

s fairly cheap, I ran #2 copper

re capacity out

Wes

This should be OK although a 60 amp breaker feeding a sub panel usually is acceptable. It is an exception to the code as I remember. The subpanel in this case does not usually employ a main breaker. The panel is fed directly to the buss bars in the sub panel. Probably depends on the inspector. I do this in my shop and the subpanel is a

125 amp panel. The bus bars have a provision to fed them without a breaker. If a main breaker were required it would be fed to the breaker terminals through the breaker onto the buss bars in the subpanel.

There are other types of panels that have terminals to feed the panel and then install a breaker between the terminals and the buss bars. I believe this is called a service panel and the subpanel that is being discussed here is a branch circuit breaker panel or branch circuit panel. Take a look at HD next time at the different panels available.

"

He must own shares in one of the copper wire companies. Copper is not cheaper, although it is better.

Harold

Wire size starting with the smasllest

#10 #8 #6 #4 #3 #2 #1 #0 or 1/0 "one ought" #00 or 2/0 "2 ought" #000 or 3/0 "3 ought" #0000 or 4/0 "4 ought"

350 MCM or 350,000 circular mils. 500 MCM

Normally #4 (in copper) is good for 100 amp, however you must go up one gauge size for every 50 feet. Looks like #0 to me. Ground wire will stay at #6.

Thank You, Randy

Remove 333 from email address to reply.

In article , stryped wrote: : :He said I cant use the 2-2-4-6 wire the local supply house is tryign :to sell me. He said aluminum would have to be #1 if in conduit and 1/0 :if direct buriable. He said copper would be cheaper.

Maybe "cheaper" as in, "If you do it with aluminum I'll find some reason to make you do it over."