Wiring question. Splicing DC wires.

[abelov1984]

Splicing DC conductors of PV circuit (PV wire #10) in JBs (on the roof) with THHN (#10) for going to the home run in the conduit. And using wire nuts for splicing..Big deal?
Thx

[Amy@altE]

A better solution is to use a Burndy Unitap like a BITO4 in a junction box.

[Sunking]

Why would you ever need a splice?

[russ]

Why would you ever need a splice?

He is trying to go cheap with short lengths of wire?

[SunEagle]

Splicing DC conductors of PV circuit (PV wire #10) in JBs (on the roof) with THHN (#10) for going to the home run in the conduit. And using wire nuts for splicing..Big deal?
Thx

Wire nuts are never a good solution to splice wire in an outside junction box. They will eventually come apart and cause issues.

Better to use a wire termination equipment such as the Burndy Unitap that Amy suggested.

[Amy@altE]

Or even better, instead of a junction box, use a Pass thru box like Wiley Electronics Acme Conduit Entry (ACE) Pass-Through Enclosure or on an asphalt roof, a SolaDeck 0786-3R5 for pass-thru and roof penetration into conduit.

[abelov1984]

unitaps are too expensive, compare to wire nuts.
easiest and best way probably to use MC4 in a JBs as well, but would need bigger boxes..

didn't say about splicing outside.

Jumping to THHN to make 120' home run (all enclosed).
Yes - cheaper installation. smaller JBs, smaller conduit, smaller penetration LB's and etc.
thx

[Amy@altE]

unitaps are too expensive, compare to wire nuts.

Unitaps are more expensive than wirenuts for a reason. Unitaps are cheaper than a fire.
Not sure if you are getting the system inspected, but most AHJ don't like wirenuts there, they like Unitaps.

[Living Large]

unitaps are too expensive, compare to wire nuts.

It sounds like you have answered your own question. Use the wire nuts if that is what you want - you will have to determine for yourself if it is a big deal.

[abelov1984]

I guess I did, but with your help..

However wanted to hear electricians, saying something about prevent dc arching, and about long term of wire nuts splicing (that are on the market right now) like 15-20 years. Inspection here won't go on the roof, but I'm wondering about quality of installation.
Thx

[Mike90250]

Wire nuts are NOT for exposed locations. Maybe for a low power lawn sprinkler system, but not utility power where they see weather hot cold cycles, moisture condensing on them....... Wire nuts OK indoors on lower amps wiring.

[Sunking]

Wire nuts are not permitted in damp or moist locations for power and lighting. End of story. There is no good reason to have any splices. Would indicate a poor design and/or workmanship.

[foo1bar]

There is no good reason to have any splices. Would indicate a poor design and/or workmanship.

There's apparently at least 3 people who disagree with that:

http://forums.mikeholt.com/showthread.php?t=168428

But they're not using wirenuts either, which I would not do.

[Amy@altE]

Wire nuts are not permitted in damp or moist locations for power and lighting. End of story. There is no good reason to have any splices. Would indicate a poor design and/or workmanship.

It's not so much a splice as transitioning from PV Wire from the panels to THHN in the conduit to inside. Which requires a pass-thru box, not wire nuts. I don't have my code book on me, but I thought PV wire was not supposed to go in conduit, thus the transition. I may be wrong, it could just be a cost thing, THHN is much less $ than PV Wire. Either way, don't use wire nuts in a moist location exposed to heat/cold. They will fail.

[russ]

There's apparently at least 3 people who disagree with that:

http://forums.mikeholt.com/showthread.php?t=168428

But they're not using wirenuts either, which I would not do.

Lots of people may disagree - no big deal as they are allowed to be wrong.