non linear loads

[jjwsjoberg]

I have a question on non linear loads. I want to run three networks in a 3/4 inch pipe. Three phase 4 wire. Pulling number 12 thhn. Is this ok in a small office building with flourecent lighting. The code states when non linear loads are the mojority of the load you count the neutral. Which would make the ampacity down to a 15 amp but what is considered most of the load. Is this a factor or is the small scale of the little bit of lighting and computers in the small office feed on a 200 amp panel ok to be considered linear. I quess my question is if that is true than are all loads other than electric heat and incondesant lighting victim of counting neutral? This would mean in most commercial buildings all recep and lighting circuits would need to have there neutrals counted for fill and derating. This seems off anyone???????????

 

[jjwsjoberg]

Can anyone answer the question on non linear loads?

Can anyone answer the question on non linear loads?

Can anyone answer the question on non linear loads

 

[LarryFine]

Yes, JJ, count the neutral as CCC when the majority (more than half) of the load is non-linear, such as all-fluorescent lighting.

Above 9 CCC's, #12 can no longer carry 20a. I'd compare using #10 and fewer 20a circuits vs. #12 and more 15a circuits.

Added: Please be patient. We're not paid for our time here. (In money, that is. In many other ways, we're steeped in riches.)

 

[infinity]

I agree with Larry. In your case you would have 12 CCC's and the derating would require you to pull in #10 THHN conductors or run an additional raceway and split the circuits up to maintain a 20 amp amapcity. Also conduit fill and derating are two different entities. For fill every conductor counts regardless of whether it's a CCC or not.

 

[mityeltu]

I'm interested in this question too. Is this rule applied to branch circuit or panel? What I mean is, if I have a branch circuit feeding 51% non-linear loads, supplied from some panel with only that one branch loaded with non-linear loads, does the "majority" of non-linear loads refer to the branch circuit or the panel as a whole?

Because the code discusses conduit fill etc, I am inclined to believe that it applies to the branch and not the panel, but I thought it was worth asking.

 

[LarryFine]

What I mean is, if I have a branch circuit feeding 51% non-linear loads, supplied from some panel with only that one branch loaded with non-linear loads, does the "majority" of non-linear loads refer to the branch circuit or the panel as a whole?

Both, or each.

If the circuit's loads are primarily non-linear, it applies to that circuit.

If a panel's load is primarily non-linear, the rule applies to the feeder.