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?
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?
Re: How many recptacles#92604 03/29/0509:52 AM03/29/0509:52 AM
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
Re: How many recptacles#92605 03/29/0502:31 PM03/29/0502:31 PM
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).
Re: How many recptacles#92606 03/29/0502:40 PM03/29/0502:40 PM
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.
~~ CELTIC ~~ ...-= NJ =-...
Re: How many recptacles#92607 03/29/0503:11 PM03/29/0503:11 PM
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.
Re: How many recptacles#92609 03/29/0505:03 PM03/29/0505:03 PM
Can I ask you why you feel it is not a violation of 210.21(B)(3)?
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
Re: How many recptacles#92610 03/29/0507:16 PM03/29/0507:16 PM