annqueue
New member
- Location
- front range, Colorado
Hi all,
I've been googling at length for the answer to my question and posts here keep popping up - which have been very helpful. Can y'all check my thinking before I haul off and buy parts?
We recently put a bunch of PV on the roof to power baseboard heaters (yes, not the most efficient use of PV, but that's not what I'm here to discuss).
We're now ready to put the heaters in. The breaker box is located outside; it has one hole out the back through the brick wall into the house. That hole is full. We're looking at using a knockout in the bottom of the box and an LB condulet with a new hole through the wall to run the required wires. I was thinking THHN in the conduit, running to a junction box in the stud portion of the wall where I'd switch to NM-B. I'd use watertight compression fittings at the panel and both sides of the condulet. We have some 1" left from the PV project.
We need to run 3 12-2 wires plus one 6-3 wire for a new stove.
This run between the breaker box and junction box should be less than 24", so really I shouldn't have to derate at all. I'm thinking it'll be about a foot, 18" long at the most.
My best guess, from the info I've found, is that a 1 inch EMT conduit is theoretically sufficient. I looked at the fill charts and it looks like 4 6-gage wires fit in the same hole as 16 12-gage; add that to 9 12-gage and you get 25 12-gage wires, which the chart says fit in a 1-inch conduit.
My questions:
Is it realistic to fit nine 12-gage plus four 6 gage wires in a one inch conduit?
Would it make sense to oversize the conduit to leave room for future work? (It looks like there's a 2-inch knockout...)
Would it make more sense to use two 1-inch holes in case the NEC decides to reduce the length of run that must be derated?
Do they ever look at conduit size when decidiing about derating? It seems crazy that there's no relationship between size of conduit, gage of wire, and the derating factor. It's just a magic number of wires.
Do I need a watertight fitting between the conduit and (non watertight) junction box in the wall?
Thanks for any clarifications you can provide.
I've been googling at length for the answer to my question and posts here keep popping up - which have been very helpful. Can y'all check my thinking before I haul off and buy parts?
We recently put a bunch of PV on the roof to power baseboard heaters (yes, not the most efficient use of PV, but that's not what I'm here to discuss).
We're now ready to put the heaters in. The breaker box is located outside; it has one hole out the back through the brick wall into the house. That hole is full. We're looking at using a knockout in the bottom of the box and an LB condulet with a new hole through the wall to run the required wires. I was thinking THHN in the conduit, running to a junction box in the stud portion of the wall where I'd switch to NM-B. I'd use watertight compression fittings at the panel and both sides of the condulet. We have some 1" left from the PV project.
We need to run 3 12-2 wires plus one 6-3 wire for a new stove.
This run between the breaker box and junction box should be less than 24", so really I shouldn't have to derate at all. I'm thinking it'll be about a foot, 18" long at the most.
My best guess, from the info I've found, is that a 1 inch EMT conduit is theoretically sufficient. I looked at the fill charts and it looks like 4 6-gage wires fit in the same hole as 16 12-gage; add that to 9 12-gage and you get 25 12-gage wires, which the chart says fit in a 1-inch conduit.
My questions:
Is it realistic to fit nine 12-gage plus four 6 gage wires in a one inch conduit?
Would it make sense to oversize the conduit to leave room for future work? (It looks like there's a 2-inch knockout...)
Would it make more sense to use two 1-inch holes in case the NEC decides to reduce the length of run that must be derated?
Do they ever look at conduit size when decidiing about derating? It seems crazy that there's no relationship between size of conduit, gage of wire, and the derating factor. It's just a magic number of wires.
Do I need a watertight fitting between the conduit and (non watertight) junction box in the wall?
Thanks for any clarifications you can provide.
