oops?

LipCa · 10-23-2007, 02:01 AM

I came across this in a recent post:

"As for installing the SER in the PVC, some authorities will not allow you to pull anything other than single conductors (not saying single strand) cable in a conduit because of heat buildup"

Here's my senario........

I came across some overhead cable previously installed by the power co to power a portable sawmill. About 300 feet of it.
It was two separate coated wires of aluminum wound around a al/steel core(which I believe was used to attach it to the poles). Pretty heavy duty stuff...about the size of a pencil.

I would have called it a "service line"?

Anyway, I have buried 100 feet of it(three separate coated wires) in pvc conduit to provide a 40 amp service to an outbuilding.
I was then told by someone that it would heat up in the conduit and I should not use it.

So, I started searching and found the above post.

Is aluminum not going to work?

robertmee · 10-23-2007, 07:18 AM

That was from my thread. The cable I had was SER which had 4 conductors (three insulated and one bare) but they were all contained in a heavy vinyl insulation. Because of the heat issue, I just cut away the insulation so that I now had three separate conductors not bound by common insulation (I disposed of the bare conductor which I didn't need, and used the other three which still have their own insulation).

It sounds like you have the power line type wire that POCO's use from their drop pole to a home via an overhead service. They are not in a common insulation, so from that standpoint, it should be fine. HOWEVER, I don't know the rules for using this type of cable in an underground service, so hopefully one of the pro's here will lend their advice.

jbfan · 10-23-2007, 02:15 PM

What you have is not allowed to be installed in conduit. It is only allowed to be installed in open air.
I would not apply power to this wire at all and remove it. I would use the correct wire.
Aluminum wire is fine, but I would use copper. #8 thwn, and you may need 4 wires.

ChristopherSprks · 10-23-2007, 02:26 PM

Quote:

Originally Posted by jbfan

What you have is not allowed

to be installed in conduit. It is only allowed to be installed in open air.

Yes... what jbfan said is correct !!!

LipCa · 10-23-2007, 07:10 PM

OK......back to the drawing board.....

I will dig up and replace with copper.

Thank you very much.

NateHanson · 10-23-2007, 09:37 PM

If it's in conduit, no need to dig it up! Just tie some strong twine to the wire, pull it out of the conduit, and use the twine to pull the right stuff through the conduit.

LipCa · 10-24-2007, 01:46 AM

Easier said then done!

Eight 90 degree sweeps in the line!

jbfan · 10-24-2007, 07:37 AM

Nothing like pulling wire through 2 circles!

NateHanson · 10-24-2007, 07:48 AM

Quote:

Originally Posted by LipCa

Easier said then done!

Eight 90 degree sweeps in the line!

ouch!

elkangorito · 10-24-2007, 09:06 AM

What about voltage drop & "fault current" temperature rise?

ChristopherSprks · 10-26-2007, 08:43 PM

Quote:

Originally Posted by LipCa

Eight 90 degree sweeps in the line!

Hope you didn't finish the wire replacement.
You DO need to dig
NEC 2005
Art. 342.26 Bends — Number in One Run
There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.

Limiting the number of bends in a conduit run reduces pulling tension on conductors and helps ensure easy insertion or removal of conductors during later phases of construction, when the conduit may be permanently enclosed by the finish of the building. Adjustments during that time are often impossible. The Code does not limit the pull points to conduit bodies and boxes; these are only examples of pull points.

LipCa · 10-27-2007, 11:31 AM

I did not pull the original wire through the conduit...I installed the conduit over it, one piece at a time.

I can put a "breakpoint" in the middle when/if I install copper.

I say "if" as I am now confused....

I talked to a 30 year power co. lineman and he said there should not be a heating problem with that wire with only a 100 foot run and 40 amps.

He knew what type of wire I was using.....

??????

Andy in ATL · 10-27-2007, 01:53 PM

Quote:

Originally Posted by LipCa

I talked to a 30 year power co. lineman and he said there should not be a heating problem with that wire with only a 100 foot run and 40 amps.

He knew what type of wire I was using.....

??????

Although they may say different, POCO employees ARE NOT electricians

...They are linemen.

Different rules and a whole 'nother ballgame!

joed · 10-27-2007, 02:02 PM

Quote:

Originally Posted by LipCa

I did not pull the original wire through the conduit...I installed the conduit over it, one piece at a time.

I can put a "breakpoint" in the middle when/if I install copper.

I say "if" as I am now confused....

I talked to a 30 year power co. lineman and he said there should not be a heating problem with that wire with only a 100 foot run and 40 amps.

He knew what type of wire I was using.....

??????

You must start over. You are not permitted to install the pipe over the wire. The conduit system must be completed and then the wire installed. The glue from the joints will damage the wire.

jwhite · 10-27-2007, 02:20 PM

I agree with joed,
also any wire installed underground must have a wet locations rating if in conduit, and an underground rating if not in conduit.

You should replace this wire with suitble wire, and fix the conduit run. What you do not want is to have someone walk across the ground, and become electricuted.

Yes it can and does happen. That is why the codes were written.