My house has it's main panel outside next to the meter. Currently there are 6 or so 1/2" conduits running down the brick about 4 feet, then through holes punch into the brick to get to the crawlspace. Each of these conduits have 1 or 2 14/2 (w/o ground) in them. I'm planning on slowly replacing these circuits with 12/2 (w/ ground). My question is: Given the length of the conduit how many cables can I fit into each conduit? What if I used some of the larger knock outs and used conduit up to 1 1/2 inches?


Or... would I be better served moving the main panel to the utility room addition that we are just finishing putting the walls in? Are there any requirements on the stud wall that the panel would be placed in? I ask because the wall that it would get put in is not load bearing, so I don't know if needs special "securing" to the rest of the structure. If we moved it in like this, I would probably treat the panel in the laundry room as a sub-panel at first, until I can get an electrician out to re-wire from the meter box to the new sub panel.

Thanks!

 

Do I understand correctly that the entire circuit is not in conduit, just a few feet of conduit for protection? Also, the cable in the conduit is romex-like NM?

If so, code requires that for calculation purposes, an oval or flat cable be considered round at its widest point. Thus, a 12/2 NM may be the equivalent of a 1/2" round cable! Using those figures, I would guess that only one NM cable is allowed in 1/2" EMT.

I think I would replace the 1/2" EMT with four or five 1" PVC runs and run the cables through those. According to derating rules, you must de-rate the cables if they are in the conduit for more than 24". Therefore, four 1" PVC runs with 3 romex each would be better than a single 2" with 12 romex for example.

 

Correct, the entire circuit is not in conduit, just approximately four feet or so. Yes, it is Romex NM.

Ah derating.. I believe I read a long thread on that just a few hours ago. If memory serves, if there are more than 3 current carrying conductors in any conduit (no matter the size?) you must de-rate the cables by a certain percentage. For example (not sure if these numbers are correct, just asking about the conecpt) if you had 4 12/2 cables in a conduit for more than a length of 2 feet, then you must use 15-Amp circuit breakers instead of 20-Amp, correct?


Any thoughts on moving the panel from outside?

 

It's actually 7 conductors (3 romex), but with 12 gauge wire it's nine conductors (4 romex) for another more confusing reason involving temperature ratings.

 

And this is in any conduit, regardless of it's size?

 

Derating is independent of conduit size.