With the popularity of the wireless LAN, lots of active equipment with flexilbe cord (wireless acess point equipment), which requires a 120V receptacle are installed on the ceiling. Usally, it goes inside of the recessed enclouse and a 120V receptacle is located in there. Is this acceptable as far as 400.8 is concerned? Thanks.
Flexible cord above a suspended ceiling (NEC 400.8)
- Thread starter jkim780
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hmspe
Senior Member
- Location
- Temple, TX
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- PE
I consider a "wall wart" power supply to be a greater hazard than a line voltage cord because of the heat generated in the power supply. I would probably use 300.21 to reject this kind of installation.
If I was designing one of these systems today I'd recommend using network powered equipment (Article 830).
Martin
If I was designing one of these systems today I'd recommend using network powered equipment (Article 830).
Martin
hmspe said:
I agree with your reasoning somewhat, but is a "wall wort" transformer going to any hotter than that 60 deg C wiring? Or is it any hotter than that 50KVA transformer I'm allowed to put above the ceiling.
I don't think 300.21 really applies, because it refers to the spread of fires - i.e holes and openings in walls and floors. It doesn't say anything about restricting devices that might "start" a fire. We have the rest of the NEC for that.
Steve
hmspe
Senior Member
- Location
- Temple, TX
- Occupation
- PE
Citing 300.21 was an off-the-cuff response. That said, my take on 300.21 is that if there's a fire a wall wart will not fare well and will contribute to the spread of the fire. It's not the strongest argument, but there's really not a lot about this in the NEC. This is a case where, if I was inspecting, I'd rather make a weak call to try to stop what I see as a true safety hazard than do nothing.
My opinion is that wall warts tend to be cheap. They have components in them that can fail and/or catch fire. Not a good thing to put above a ceiling, out of sight. I've had them get hot enough that the 115VAC prongs melted through the case. A 50KVA transformer will also get hot, but it will have clearance and will have reasonable overload protection. I doubt that a 15A or 20A breaker would trip for an overload on a wall wart.
As to the post about 300.22(C) from jkim780, it would apply only if the space above the ceiling was used for environmental air. The projects I've done that wanted receptacles like this were hotels, and 300.22(C) would not have applied.
I think this issue needs more research, time for which I don't have right now.
Martin
My opinion is that wall warts tend to be cheap. They have components in them that can fail and/or catch fire. Not a good thing to put above a ceiling, out of sight. I've had them get hot enough that the 115VAC prongs melted through the case. A 50KVA transformer will also get hot, but it will have clearance and will have reasonable overload protection. I doubt that a 15A or 20A breaker would trip for an overload on a wall wart.
As to the post about 300.22(C) from jkim780, it would apply only if the space above the ceiling was used for environmental air. The projects I've done that wanted receptacles like this were hotels, and 300.22(C) would not have applied.
I think this issue needs more research, time for which I don't have right now.
Martin
Reviewed 400.8 again, and I don't think 400.8 applies here. The enclouse is recessed in the ceiling (regardless of ceiling type, ceiling grid or gymsum) and has a locking acess door. 400.8 only applies if the flexible cord runs through or concealed by walls, floors or ceilings.
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