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#92601 - 03/28/05 07:23 PM How many recptacles
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Here's the suitiation: Industrial setting, #12 THHN, dry location, 45 wires (current carrying) in the wireway. How many 120v. 20a. receptacles can I install on this #12 wire circuit and what size overcurrent device should I use?
_________________________
George Little

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2014 / 2011 NEC & Related Books and Study Guides
#92602 - 03/28/05 08:03 PM Re: How many recptacles
PCBelarge Offline
Member

Registered: 06/08/03
Posts: 657
Loc: Dobbs Ferry, NY, USA
376.22
45 conductors = 35% multiplier
30 amps X .35 = 11.4 amps

Thats not much, If you did not install this yet, maybe you should think of a different wiring method.

It comes out to 7 receptacles per branch circuit as per 180 VA per device.
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Pierre Belarge

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#92603 - 03/29/05 04:16 AM Re: How many recptacles
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
PCBelarge- Actually I came up with 6 receptacles but you and I are on the same wave length. You failed to answer the second part of the issue, what size overcurrent device would you use for this circuit?
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George Little

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#92604 - 03/29/05 06:52 AM Re: How many recptacles
sandsnow Offline
Member

Registered: 09/21/04
Posts: 163
Loc: Irvine, CA, USA
From a practical standpoint this won't work for feeding multioutlet branch circuits.
You can't round up to the next higher OCPD because of multioutlets. 240.4(B)(1). Therefore you're must round down and although 10 amps for an inverse time c/b is permitted by 240.6(A) that's not a good design in my eyes. I thought I heard someone say they saw a 10 amp c/b.

If the circuit feeds one outlet, then you can round up to 15 amps. Better, but not an ideal design.

Better as Pierre inferred, to run more conduits and/or increase your wire size to provide a full 20 amp circuit.
_________________________
Larry LeVoir
Inspector
City of Irvine, CA

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#92605 - 03/29/05 11:31 AM Re: How many recptacles
mhulbert Offline
Member

Registered: 10/19/04
Posts: 133
Loc: Anaheim, CA USA
10A breakers do exist, the square D QO110 for example. My guess is that they are made for situations like this. Maybe if you knew that there would be fixed, steady loads, like a computer lab or something, this would be OK, however I see nothing in Article 210 that mentions 10A circuits.


I would use larger wire, or maybe look in to a divider to split it in to 2 raceways (if your ahj is OK with that).

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#92606 - 03/29/05 11:40 AM Re: How many recptacles
Celtic Offline
Member

Registered: 02/26/05
Posts: 367
Loc: NJ
How long is the wireway - is it actually a nipple (less than 24")?
To load a pipe up with 45 #12's is madness!
My answer:
"How many 120v. 20a. receptacles can I install on this #12 wire circuit and what size overcurrent device should I use?"
As many as you like...
..because it ain't gonna work right no matter what you do.
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~~ CELTIC ~~
...-= NJ =-...

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#92607 - 03/29/05 12:11 PM Re: How many recptacles
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
mhulbert

 Quote:
10A breakers do exist, the square D QO110 for example. My guess is that they are made for situations like this.


As sandsnow pointed out you can not feed multiple 15 or 20 amp receptacles with a breaker rated less than the receptacle.

If you do use a 10 amp breaker you violate 210.21(B)(3).

Celtic

 Quote:
To load a pipe up with 45 #12's is madness!


A wireway is not a pipe and is not subject to the same derating rules.

That aside I quite often install 28 - 10 AWGs in a raceway to feed 20 amps circuits.
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Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#92608 - 03/29/05 01:49 PM Re: How many recptacles
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
Thank You Gentlemen and ladies if there are any commenting. I am not the installer but only looking at this problem as an inspector. I agree with the general consensus that it is a poor design. But, I'm only the inspector, what do I know
I don't see it as a violation of 210.21(B)(3) since the code is silent on 10 ampere circuits. So, if I'm derated to 10 amperes as the overcurrent device and the voltage is 120v. The circuit has the capacity of 1200va. Divide by 180 = 6.6666666 receptacles. Stupid but code compliant.
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George Little

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#92609 - 03/29/05 02:03 PM Re: How many recptacles
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
George it's your call as your the man.

Can I ask you why you feel it is not a violation of 210.21(B)(3)?

2002 NEC
 Quote:
210.23(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or where larger than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.


Notice the options for receptacles larger than 50 amps, that leads me to believe receptacles less than 50 amps do not have an option.

When we look at the Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits we see 15 amp circuits use 15 amp receptacles and 20 amp circuits use 15 or 20 amp receptacles.

No mention of 10 amp circuits.

I agree with you if we are talking about single receptacle circuits.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#92610 - 03/29/05 04:16 PM Re: How many recptacles
sandsnow Offline
Member

Registered: 09/21/04
Posts: 163
Loc: Irvine, CA, USA
iwire is correct on that multi recep thing.
I remember this came up in another thread. My brain is like jello.
_________________________
Larry LeVoir
Inspector
City of Irvine, CA

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