Two offices with fifteen 20 amp recepticals, the circuit are run in a 2" emt to a 4 X 4 wireway then down to outlets. This is a question about de-rating, the conductors are #12 thhn there are 31 wires in the 2 conduit. looking at the table 310.15(B)(2)(a) 31-40 wires they can only carry 40% of their rated load. That would mean they can only carry 8 amps, and not be connected to a 20 amp circuit breaker. would this be a code violation
20 amp branch circuits
- Thread starter Dbronx
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The run is 75 feet and each circuit feeds one outlet, the loads are non linar. In this case the neutrals would not be considered current carrying conductors. that would mean only 15 current carrying conductors allowing 50% of load rating up to 10 amps per circuit. That is still well below 20 amp rating of the circuit breaker.
Let me clarify the last post .The run is 75 feet and each circuit feeds one outlet, the loads are non linar. In this case the neutrals would not be considered current carrying conductors. IF yes then conductors allowing 50% of load rating or up to 15 amps per circuit. That is below 20 amp rating of the circuit breaker. I made a first year de-rating mistake, a#12 wire rating from 90? colum is 30 amps then apply TBL 310.15(B)(2)(a) 10-20 wire 50% is factor . My solution is to pull #10 wire from panel to 4 X 4 wireway and splice to #12 wire down to outlets. Would this be code compliant, or is it necessary to up size wire?
View attachment Office.pdf
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If you have 2-wire circuits the neutrals would count as a CCC. If you have non-linear MWBC's then the neutrals would also count as CCC's. What kind of circuits do you have?
Let me clarify the last post .The run 2" is 75 feet with 31 #12 wires for 15 circuits. And each circuit is two wires feeding one outlet. The wireway is 25 feet long.
A #10 wire rating from 90? colum is 40 amps then apply TBL 310.15(B)(2)(a) 31-40 wire 40% is factor = 16 amps. The next higher breaker 20 amp, the lowest rated circiut breaker in panel is 20 amps. My solution is to remove #12 wires from 2" pipe to wierway, pull #10 wire in 2" pipe from panel to 4 X 4 wireway, and connect #10 wire to #12 wire in wireway down to outlets. Each conduit run down to outlet has just 3 #12 wires in it. Would this be code compliant, or is it necessary to up size wire?
Office.pdf
A #10 wire rating from 90? colum is 40 amps then apply TBL 310.15(B)(2)(a) 31-40 wire 40% is factor = 16 amps. The next higher breaker 20 amp, the lowest rated circiut breaker in panel is 20 amps. My solution is to remove #12 wires from 2" pipe to wierway, pull #10 wire in 2" pipe from panel to 4 X 4 wireway, and connect #10 wire to #12 wire in wireway down to outlets. Each conduit run down to outlet has just 3 #12 wires in it. Would this be code compliant, or is it necessary to up size wire?
Office.pdf
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
You said each circuit only had one outlet/receptacle, so 240.4(B) would apply to the 16A from the derating of the #10 wire. You would need to upsize the 12 to #10 if you plan on keeping the 20A OCPD. Otherwise, if you kept the #12, that would derate to 12A and you would have to change the breaker to a 15A to be compliant.
- Occupation
- Licensed Electrician
Yes. It is compliant.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
What do you mean by one outlet? Is it a single receptacle or a duplex receptacle? A duplex receptacle means that you cannot use the next size up rule in 240.4(B).
I am not as sure. To me the NEC wording makes it a bit tricky.
240.4(B) allows "next size up" provided the conductors being protected are not part of a "multioutlet branch circuit supplying receptacles for cord and plug connected loads".
When you look at the definition of a "Receptacle", a "multiple receptacle is two or more outlet devices on the same yoke"
So, I wonder, if taken literally, in this situation if the OP is feeding a duplex, he's feeding a multiple outlets, Correct ?
Seems it's possible that his plan would only work if the outlets were single
Certainly iopen to discussion/i interpretation. Were I he, I'd check to see how my AHJ was thinking.
(sorry, Rob. In the time ti took me to type, you had already replied. I left mine only to show at least two of us question the install)
- Location
- New Jersey
- Occupation
- Journeyman Electrician
We agree. He needs to clarify as to whether or not his use of the word outlet means single or duplex receptacle. With single receptacles his calculations for #10 AWG conductors in the 2" raceway will be compliant. With a duplex receptacle on each circuit he will need to use a larger conductors which may not fit in the 2" raceway.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I disagree. You're definition in red above says outlets, but the definition actually says contact device.
The definition of receptacle outlet says "an outlet where one or more receptacles are installed.
240.4(B) says in part, ..."not part of a mulitoutlet"
Since the receptacle in question is only one outlet, I think it is compliant, IMO.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
So you're saying that by definition an duplex receptacle is two receptacles but only one outlet?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
- Location
- Massachusetts
Each receptacle on the single yoke is a point on the wiring system at which current is
taken to supply utilization equipment unless you are saying you cannot run two pieces of utilization equipment from it.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I'm saying it is only one outlet.
- Location
- Massachusetts
I know you are saying that but you are mistaken, two receptacles is two outlets even when mounted on a single yoke.
- Location
- Illinois
- Occupation
- retired electrician
It doesn't look like a receptacle is an outlet. A receptacle is installed at an outlet.
But then when you look at "outlet", it is not as clear.
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