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| Subject - Panel Homeruns | |
| David Hyatt |
When shielding Romex inside a wall coming to a panel with say a 2" conduit, do you have to derate ampacity if the conduit is over 24"? Code Ref please. This is just to shield the wire through the ceiling plate. Also, I was on a job recently and ran an 1 1/4 PVC nipple from the panel through the ceiling for future wiring. To me I was looking ahead, doing something over and above what most would do. The inspector made me take it out, said it was a fire hazard. Even though I have done this many times in the past. Whats your opinion of that? |
| SteveMc | Chapter 9 Note (2)--Table 1 does not apply to incomplete conduit systems.. Also Note (4)--Nipples not to exceed 24" may b filled to 60%... I've often done exactly what you've described and never had a problem with it. I always keep the nipple less than 24". Could there be something in the fire codes that prohibits this practice? |
| Ryan_J | 310.15(B)(2)(a), I think...don't have book here right now. |
| David Hyatt | That ref is for raceway, would this be considered a raceway. It is not complete? Tom Henry made ref to this in one of his videos but can't find it in the code. If it is not a complete raceway just shield there are not any derating factors. |
| JimmyDee | quote: I've put a pipe cap on the end of the conduit and that should satisfy the inspector. I always, now, run a 2" PVC from the mechanical room to the attic and cap both ends. Its just a chase for anyone to use and it usually does get used. Jim |
| David Hyatt | Thats what I am talking about, make it easy for the future. Who knows they may call you back. If it had one wire in it it would not be a fire hazard, but empty it would. That makes no sense, Guess its these Greenville inspectors. |
| Electricman | David, I remember reading something that this was allowed in surface mounted panels only somewheres around the 312 section I think, I will check, I left my code book in my work truck. Ryans right about the derating. I think that has to do with # of conductors and length of raceway. |
| David Hyatt | Still not convinced it is considered a raceway Electricman. I know if 24" are less its not but the definition of raceways doesn't specify complete. I would like more input on this matter and code ref if available. |
| karlwayne | David, I believe the answer is yes according to article 310-15(b)(2)(a). Even if you didn't use a conduit sleeve, and bundled romex or mc cable (for more than 24"), the adjustments in the table should be in effect. |
| David Hyatt | It does seem to read that way, after reading it again. But it hard to comprehend. When I install an outside panel on a service upgrade I will usually come out of the bottom with a 2" PVC to an LB and trough the wall. Some times it may be 3' of conduit instead of 24" and I install every circuit in the house 120 & 240 in this one conduit. This will mean a 45% derate on all the circuits.? Maybe 15 110 volt and 4 or 5 220 volt. That seems hard to swallow. And besides that if you dress the panel connections with tie wraps, they are bundled, do you have to derate? I would not know how to wire a house if I had to derate all the romex in that 2" conduit. Is there a better way. I have had to run (2) 2" conduits if one was not big enough. My theory has always been in this situation if they will fit put them in. Open for suggestions. |
| Electricman | David, read 312.5 (C)exception: this may be the code the inspector was applying. |
| David Hyatt | Electricman, I see whats going on now. And this section also talks about no more than conduit not more than 10' in length. It doesn't say anything about ampacity derating. I am convinced in this above situation derating does not apply. |
| David Hyatt | OK, I called Tom Henry in Florida, spoke with his assistant. Turns out this is a very controversial subject. By code as stated previously, over 24", romex in a conduit sleeve, or bundled, more than 3 current carring conductors, derates do apply. In his opinion as well as mine this is something that should be changed. Nevertheless, it is code. I knew thats the way it read but couldn't comprehend it. Still can't. Don't see a better way of doing it. Never seen it enforced. Probably hard to enforce because in a residence the exact load can't be determined on general purpose anyway. Also conduit fill doesn't apply because it is not a complete raceway. My way of doing this is common practice around here so I think unless someone has a better idea I will continue doing it without concerning derates.
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| cs409 | seems like the NEC needs to be written in a more user/understandable means instead of written on the level of legal minds! the party of the first part unless the party of the second part or maybe the party moved across the street.....will the people doing to NEC please read what you put into print! then after you read it, redo it an make it clear, to the point...!!!!... LOL |
| SteveMc | David, I'm with you on the 2" conduit for an outside panel. How else do you manage to get all your wires into the panel? Anyone else have any ideas or suggestions here? That's the way it's usually done here in the northern part of SC anyway. |
| WELLSEROUSKI | I'm in San Antonio and I have not run into this problem BUT other electricians I've talked to say their inspector had turned them down because all their branch circuits to the sub-panel entered through a 2 1/2" pvc. male adapter in the middle of the breaker panel. The inspectors say that this derates the wire so with these guys they had to put all circuits in romex clamps coming into the panel. I think I have read that all branch circuits going into a branch feeder panel must be clamped down according to the International Building Code ( 2003 ). Although I've never been called on it. Rich. |