100 Amp Circuit

[billg]

Hi. I need to run a 100 Amp 2 pole circuit about 60 feet to power the electric backup heat for my geothermal heating unit.
From the tables I've looked at I think I need to use 2/0 copper for the run. So I'd have 2/0 for the two hot feeds from the breaker.
If that's right, what guage wire do I need to run for the neutral and the ground wire?
Also am I required to run all of this in conduit?

Thanks!

Bill

[HayZee518]

Assuming the run is straightforward - a # 6 will safely carry a 100 amp load. My calculations are based on this site.

http://www.ifigure.com/engineer/electric/electric.htm

[billg]

Oh my. I'm no expert but I know for a fact that #6 will not suffice for a 100 circuit. I'll be using #6 for my 60A runs.

[HayZee518]

In that case #2 copper will run a 100 amp panel. Neutral will be the same size while #6 will suffice for the bare ground.

[kactuskid]

You want to install #2 copper for the 2 hots and #2 copper for the neutral, though can reduce to #4 if you want. And install a #6 or #8 copper wire for the ground. All this needs to be THHN/THWN insulated wire placed in 1 1/2" conduit (grey plastic) and buried 18" deep. Be sure to install expansion joint couplings at each end of the conduit.

You really need to check what your local codes are as they rule and may vary.

[billg]

Buried? This is running in my basement to a geothermal unit, not a sub panel.
I ended up going with 2-3 insulated. No need for the conduit.
This is what the union electrician suggested.

[kactuskid]

Your union electrician is wrong. Per code you cannot run this wiring without enclosing it in conduit, absolutly not. No where would this be allowed. If installing in your basement then you need to use either EMT or PVC.

[HayZee518]

Kactus ol buddy! What about 2/3 armored cable! Almost like BX! You'll have your two hots and neutral and the jacket will suffice for the ground!

[billg]

According to the Int. building code...
You only need to use conduit if the wire is not coated.
I have 4 insulated wires inside the outer Jacket, just like 12-3 roamex. You don't have to run roamex in conduit.
?

[kactuskid]

Hey, your description of "ended up going with 2-3 insulated" didn't sound like any cable description I'd ever heard of. Sounded more like individual insulated wires were gonna be installed instead of insulated wires in a cable jacket. Just didn't want you to string individual wires across your basement is all. I agree, no need for conduit if they're protected by a jacket.

[billg]

Cool. THanks for the clarification!

[HayZee518]

When I worked for a contractor in Lake Placid on those multi million dollar lake camps, we pulled in 2/0-4 poly coated armored cable through 2 inch pvc on runs over 300 feet! Some runs were no less than 150 feet all sizes of poly coated armored cable to sub panels. One dwelling (camp) had 7 sub-panels. Each sub was 100 amp. One place was soo big they had a 400kw Onan backup generator with an ASCO flop over.