9 current carrying conductors ...

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Shockedby277v

Shockedby277v

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If I had 8 lights on dimmers, needing seperate neutrals but on the same circuit off a dimmer panel, I would then have 16 wires in a pipe. How would the adjustment factors from Table 310.15(B)(2)(a) work??? 70% or 50%???
 
50%. As ridiculous as that sounds. IMO if they are all on the same circuit derating should not apply but it does since they are all CCC's.
 
Shocked did you look inside the dimmer unit?

I bet dollars to donuts that the neutrals all go to one common bus and that one neutral would work fine....assuming no 110.3(B) issues.
 
iwire said:
Shocked did you look inside the dimmer unit?

I bet dollars to donuts that the neutrals all go to one common bus and that one neutral would work fine....assuming no 110.3(B) issues.
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That's probably true, but I've seen Lutron dimmers and dimming systems that require separate neutrals as part of their installtion instructions
 
infinity said:
That's probably true, but I've seen Lutron dimmers and dimming systems that require separate neutrals as part of their installation instructions
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As Don would say....Is that part of the listing or just a suggestion?

Personally I would assume it is part of the listing.
 
Ack! I have theatrical stage lighting to do in a school, where all the lights are fed from a dimmer rack. We did a similiar job back when I first started as an apprentice and I remember pulling approx 40-60 wires in a pipe. Now I know that is not the way to go. Anyone have any suggestions?? Or how they have done this before ...


No I haven't opened anything up yet. I'm months out on this but wanna get a jump on it. The reason we pulled so many wires on the other job was because we needed seperate neutrals.
 
Shockedby277v said:
Ack! I have theatrical stage lighting to do in a school, where all the lights are fed from a dimmer rack. We did a similiar job back when I first started as an apprentice and I remember pulling approx 40-60 wires in a pipe. Now I know that is not the way to go. Anyone have any suggestions?? Or how they have done this before ...


No I haven't opened anything up yet. I'm months out on this but wanna get a jump on it. The reason we pulled so many wires on the other job was because we needed seperate neutrals.
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Years ago when we did a theater we used metal wireways for the dimming circuits. The wireways had barriers in them so each side of the wireway could contain up to 30 CCC's without derating.
 
I imagine it is more cost effective than running a bunch of conduit or upsizing the wire. Does it have a visual appeal?? Do you know the name ??? wiremold?? or have link by chance?? :)
 
Assuming a 20 amp circuit and 16 current carrying conductors in the raceway 10 AWG with 90 C insulation will be adequate and is probably desirable for voltage drop reasons as well.
 
Many theaters have runs of 2.5x2.5 wireway because the derating factors of 310.15(B)(2) don't apply till you get to 30 cc conductors (See: 376.22). Barriers would also work, though, IMO, they are labor intensive if you have a lot of turns and breakouts.

However, I just found 520.6, which negates the requirements of 366.6 and 376.22 if you are in an Art 520 occupany. So, you can fill those wireways up with as much wire as you can handle. This is most likely allowed because of the non-continuous nature of theatrical lighting. The exemption applies to all wiring, not just lighting, so it could be abused. Also, be carefull on long vertical runs, you'll need to support the wire somehow.

Shocked, you want something from a company like Hoffman or Wieggmann to WireGuard. Try: http://www.hoffmanonline.com/produc...t_1=34&cat_2=2358&SelectCatID=2358&CatId=2358
 
hardworkingstiff said:
I would say 70% per Annex B Table B.310.11
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You can not use B.310.11 unless you are under engineer supervision.

B.310.15(B)(1) Formula Application Information.
This annex provides application information for ampacities calculated under engineering supervision.
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iwire said:
Assuming a 20 amp circuit and 16 current carrying conductors in the raceway 10 AWG with 90 C insulation will be adequate and is probably desirable for voltage drop reasons as well.
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That would be for a 1" conduit
Rick
 
infinity said:
Years ago when we did a theater we used metal wireways for the dimming circuits. The wireways had barriers in them so each side of the wireway could contain up to 30 CCC's without derating.
Click to expand...
just finished a major theater remodel in march of this very year. definatly was not what i was exexpecting. expect the worst and hope for the best.
 
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