2 questions, wire gages and jbox

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  #1  
Old 02-11-06, 03:19 PM
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2 questions, wire gages and jbox

I also recently added two overhead lights on the unfinnished side of my basement over my work bench. I read in an electrical book that I should not mix wire gages. ie 14 with 12. However i had already ran these two new lights with 12 gage already stapled to the beam. The existing lights have 14. The breaker is 15amp. I don't think there's a hazard as perhaps the reverse would be, but if i want to sell the house someday is this not according to code?

Also does a junction box (exposed in unfinnished basement)have to be metal with clamps in the nockout holes or can it be pvc or heavy plastic as long as the wire is stapled on the beam close to the box?
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Old 02-11-06, 03:34 PM
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You are allowed to use heavier guage wire than is required, so #12 on a 15A breaker is fine. You are correct is saying the opposite would NOT be true...#14 on a 20A breaker is a code violation.


Codewise, I don't see a problem with the plastic jbox.

From a practical standpoint, the only problem I see with a plastic junction box in an unfinished area is that you need to use a plastic face plate on it, which could easily wind up broken since they extend so far over the edge of the box. The reason you don't normally use a metal faceplate on a plastic box is because metal faceplates must be grounded. On a metal jbox, they get their ground from the box being grounded. Thats why I personally prefer a metal junction box...
 
  #3  
Old 02-11-06, 05:32 PM
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Originally Posted by Bebop

Also does a junction box (exposed in unfinnished basement)have to be metal with clamps in the nockout holes or can it be pvc or heavy plastic as long as the wire is stapled on the beam close to the box?
thankyou
A heavier gauge can almost always be used and is sometimes done to reduce voltage drop on long runs. In any case, it is rarely disallowed. The issue with some people is that the mixing of gauges causes confusion. For example if the circuit starts with #12 at the loadcenter but reduces to #14 down the line, somebody might just open the loadcenter, see the #12, and change out the 15A breaker for a 20A.

On the j-box issue, local codes vary. You are probably OK if other wiring looks similar in your basement. However where I live romex is not permitted to be exposed in basements: Metal conduit and metal boxes are required.
 
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