How many circuits leaving one panel knockout?

[DanielVetpath]

I have a new 200 amp service panel in my shop. I am using 3/4" emt to run power throughout the shop. Question - can I run more than one circuit out of the box through one knockout hole, divided into separate conduit runs outside the box. E.g. six wires (two each of black, white, green) from two adjacent circuit breakers leave the panel box in one conduit, go to one 4x4 metal box where they part ways to leave in separate conduits for two lighting runs. Thanks for any input. Daniel (Don't know if it matters but this is in a stand alone pole building, shop only).

 

[rabidsquirrel]

Yes.

 

[DanielVetpath]

Thanks rabidsquirrel. I should have specified, I am using THHN 12 ga wire.

 

[pattenp]

Yes you can but make sure you do not exceed the allowed fill for the conduit or box.

 

[Naq]

Up to 9 current carrying conductors (4 single phase circuits + 1 wire) whenever they are run together for at least 2 feet before 90C insulation temperature derating starts to matter.

 

[kbs2244]

Just be sure to use the "deep" boxs.
Lots of thick wires need lots of room.

 

[DanielVetpath]

Naq: Good info. Just want to clarify that ground (you can tell I am definitely not in the trade!) is not considered a conductor. i.e. 4 single phase circuits refers to a black and white each as well as a green for each circuit which isn't counted in terms of conduit fill. Do I have it right?

KBS2244: Thanks. I am using 4 x 4 x 2 1/8" boxes all the way around. The guys at my local electric supply shop have been outstanding. Lots of important contractor types sitting on either side of me and they continue to show me lots of patience and give really good advice like all of you folks. Thanks again, Daniel

 

[rabidsquirrel]

Naq: Good info. Just want to clarify that ground (you can tell I am definitely not in the trade!) is not considered a conductor. i.e. 4 single phase circuits refers to a black and white each as well as a green for each circuit which isn't counted in terms of conduit fill. Do I have it right?

9 conductors means 4 circuits (black and white or black and red) and one ground. You only need to pull one ground and you just splice it in your box when you branch out.

 

[PRH44]

The ground wire is not considered a current carrying conductor. Thus it will not be counted for temperature derating. You are only required to count the phase and neutral conductors as current carrying.
As NAG stated you can have up to 9 current carrying conductors before you will be required to derate for temperature.
The ground wire will count in the overall conduit fill (The maximum conductors the code will allow to be installed in a conduit). This would be 16 #12 THHN/THWN maximum. If you stay with 9 plus your ground you will be fine and not have to consider temperature derating.

 

[Naq]

Naq: Good info. Just want to clarify that ground (you can tell I am definitely not in the trade!) is not considered a conductor. i.e. 4 single phase circuits refers to a black and white each as well as a green for each circuit which isn't counted in terms of conduit fill. Do I have it right?
...

The black and white are counted as "current carrying" so you can have any combination of them up to 9 wires and only need to derate by 70% from the 90C rating of THHN. For #12AWG THHN you end up with 30A x 0.7 = 21A which must be protected at 20A anyway.

4 single phase circuits with individual grounding conductors is 12 wires total which count against the 16-#12AWG THHN maximum for 3/4" EMT. Usually you will run one ground and tap as necessary in a single run. Every box will have a rating for the maximum number of wires, clamps, and devices as well that needs to be checked. The limits are published and sometimes shown right on the box. When you add clamps and devices or other things that start to take up space you should take allowances for those things too. Like everyone says, the box is never big enough and the wires are never long enough.

 

[DanielVetpath]

Thanks guys for clarifying difference between current carrying and temperature derating vs overall conduit fill. I have not run more than three circuits (total of 12 wires) in any single conduit run, so it sounds like I am okay. Where it gets muddied for me is calculating box fill. The box is stamped with size of just over 30 cu in. I have several boxes with two receptacles (each on the same circuit) using pigtails for everything (e.g. ground in, to box, to both receps to next box; also all white and black wires using pigtails to each recep and then down line). I am not sure whether the screw-type clamps connecting the EMT to the box count against me as well? Any comments? Thanks, Daniel

 

[PRH44]

A listed EMT set screw connector would not count