Solid or stranded for dc

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-marty

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This is so petty but I'm about to quit my job over it.

I did a solar install. I ran 10-2 w/g solid uf wire from the e-panel to the solar panels. I'll not mention the load on the wire or the distance or the temperature because I don't want to side track the issue, all were well within the recommendations of John Wiles publications.

What has my boss concerned is the fact that I used solid and not stranded for dc.

Please I'm not looking for opinions - just facts.

thanks
 
I don't see a problem either way between solid or stranded. Maybe he preferred you to use conduit and THHN or something?

What was his rationale for the 'problem'?
 
-marty said:
This is so petty but I'm about to quit my job over it.

I did a solar install. I ran 10-2 w/g solid uf wire from the e-panel to the solar panels. I'll not mention the load on the wire or the distance or the temperature because I don't want to side track the issue, all were well within the recommendations of John Wiles publications.

What has my boss concerned is the fact that I used solid and not stranded for dc.

Please I'm not looking for opinions - just facts.

thanks
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I believe that he is overreacting to the situation. If he was so concerned that it should have been stranded why didnt he mention this to you before the install?? Was there some sort of installation instructions you didnt read?? That speced out stranded. How big of a deal would it be to replace it?? Ask him what he would like you to do to correct the situation and not have to listen to an abusive idiot who is playing good dog good dog good dog..........bad dog with you . If they treat you like a bad dog. BE THE BAD DOG!!!! sorry Frizbee!!!!!!
 
Thanks for the replies. My boss is a solar supplier. His concern is that dc flows on the outside of the wire, thus stranded is superior. If I remember ac flows on the outside and dc flows through the wire.
 
-marty said:
Thanks for the replies. My boss is a solar supplier. His concern is that dc flows on the outside of the wire, thus stranded is superior. If I remember ac flows on the outside and dc flows through the wire.
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Yes this is what I was taught however welding cable is stranded for flexibility of the lead and this is what most people relate to.
 
hardworkingstiff said:
Wow, I finally met someone that might be more of a hot-head than I am. :D
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Not so fast, I can have a reputation for going from 0 - A-hole in well under a second. :grin:
 
For normal applications, both AC and DC, it is my opinion that skin effect is neglible. If it was an issue, then NEC 310-16 would need to seperate out ampacities based on solid and stranded conductors.

And here is the kicker for DC. Look at Table 8 Chapter 9 NEC on the right hand side of the table. DC resistances are given. And the solid wire has lower resistance than stranded. So solid is better for DC although the difference is neglible.

Was there a flexibility issue here which might make stranded better?
 
Well I design battery plants for Telephone companies and we do require all DC cables to be stranded and tinned for the following reasons:

  • Due to the low voltage nature we require all terminations to use irreversible compression connectors with an approved tooling system. Basically either Burndy or T&B color coded lugs and tool system.
  • Each wire skinner is to have a light coat of No-Ox applied to the skinner and the contact surface of the termination.

The two reasons is the corrosive nature of DC, and contact resistance (less than 15 micro-ohms).
 
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