Flex Conduit Fill

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  #1  
Old 12-18-12, 10:56 AM
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Flex Conduit Fill

Can I get away with 1" Flex Conduit with 8-10 pairs of #12 and 2 #10 ?
 
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Old 12-18-12, 11:23 AM
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Fill-wise, that's probably fine... BUT, you can only have 9 current-carrying conductors in a raceway without derating the wiring. That means your 12ga wire will need to be connected to a 15A breaker and your 10ga to a 20A breaker.

You'd probably be better splitting them across two or more conduits. Also, don't forget about your ground!
 
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Old 12-18-12, 03:27 PM
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Hmm...Thanks for the insight on the 9 Max.
I presume that's applicable to any gauge (regardless of fill capacity).

Yes, it's a flex run (5-6 feet) from transfer switch back to panel. The neutral and ground are the 10Awg. The remainder are 12AWG. Not that any of the circuits I am putting are nowhere even close to 20 draw. There's not even a microwave on that. The biggest draw would be the inrush from the fridge or the coffee maker.
 
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Old 12-18-12, 03:46 PM
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Sorry, but draw means nothing. Can you reduce the number of current-carrying conductors by having branch circuits share neutrals?
 
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Old 12-18-12, 05:18 PM
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Just a minor correction:

You are required to derate current carrying conductors if you have more than three wires in a raceway. However, the derateing does not really affect amp rateing of small conductors (as defined in the NEC) until more than 9 conductors is reached, so the info Nashkat providing is still true.
 

Last edited by Tolyn Ironhand; 12-18-12 at 05:46 PM.
  #6  
Old 12-18-12, 05:47 PM
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Point taken. Thanks for adding the detailed info, TI.
 
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Old 12-18-12, 06:10 PM
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Interesting read fellas. I'm not using this but is this to say, they are using 12AWG but then breakers are 15amp - except for the last 2 which are 20...

31410B Pro/Tran | Product Details | Reliance Controls Corporation
 
  #8  
Old 12-19-12, 03:34 AM
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The key there is the whip is only 18" long. You do not have to take derateing into effect if the conduit is less than 24" long.
 
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Old 12-19-12, 03:50 AM
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Got it. So I guess I'll end up running 2 conduits.

? For my Reference.
Is the neutral in the pipe considered a CC
 
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Old 12-19-12, 06:29 AM
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If it's one neutral per hot, yes, it's a current-carrying conductor, since the voltage flows down the hot and back the neutral.

If you use two hots out of phase with a single neutral, the neutral is no longer considered current-carrying.

Grounds are never considered current-carrying, only figure into fill calculations.

------

Back to TI's comment, at what wire size does the 3 current carrying conductor derating limitation figure in? For small gauge wire (14/12/10), I know it's 9 current carrying conductors in a raceway, at what point does it decrease in number?

At some point I guess I'll have to break down and buy the NEC book and plan an exciting year to read it.
 
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Old 12-19-12, 08:04 AM
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What is the temperature rating of the conductors in that whip? I think those generator panels use either 105*c or 125*c rated wire.
 
  #12  
Old 12-19-12, 09:24 AM
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I don't even have the slightest clue what they use in the whip.
I was just planning to use THNN 600V in my stash....

BTW, for 30 amps, the single #10 back should be sufficient right.
No benefit to go to a #8
 
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Old 12-19-12, 09:32 AM
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BTW, for 30 amps, the single #10 back should be sufficient right.
No benefit to go to a #8
Yes, 10 AWG is all you need for 30A.
 
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