310.15 adjustment factors

[Badgerstate]

I was told on commercial feeders and services example 3PH 4W 120/208 and 480/277 volt settings even if the neutral is considered current carrying I do not apply any adjustment factors for more than 3 current carrying conductors in a raceway.
Any comments or help?

 

[LarryFine]

I was told on commercial feeders and services example 3PH 4W 120/208 and 480/277 volt settings even if the neutral is considered current carrying I do not apply any adjustment factors for more than 3 current carrying conductors in a raceway.
Any comments or help?

If the load is 50% or more harmonic-producing loads, it makes four.

 

[Badgerstate]

I was told on commercial feeders and services example 3PH 4W 120/208 and 480/277 volt settings even if the neutral is considered current carrying I do not apply any adjustment factors for more than 3 current carrying conductors in a raceway.
Any comments or help?

What about 220.61 that is for service and feeder neutral conductors. That say no derating permitted. 310.15 adjustment factors are for branch circuits only. You agree?

 

[david luchini]

What about 220.61 that is for service and feeder neutral conductors. That say no derating permitted. 310.15 adjustment factors are for branch circuits only. You agree?

That is not correct. The 310.15 adjustment factors apply to branch circuits and feeder (and services) alike.

220.61 doesn't say anything about adjustment factors.

 

[Carultch]

I was told on commercial feeders and services example 3PH 4W 120/208 and 480/277 volt settings even if the neutral is considered current carrying I do not apply any adjustment factors for more than 3 current carrying conductors in a raceway.
Any comments or help?

Neutral generally doesn't count "current carrying" for purposes of bundling derate factors, but there are essentially two reasons why it would.
1. It is a mandatory part of the return path of the current, such that it has no other option than to carry the full load. Examples: single phase line-to-neutral loads, a branch circuit pulled from neutral and 2 out of 3 of the phases of a 3-phase system (because even balanced loads on that circuit put full load on neutral).
2. The harmonic loads are significant enough, that harmonics which accumulate onto the neutral. The NEC's phrasing of this, is a majority of the load is nonlinear.

If either of the above reasons make neutral "current-carrying", you count it as such, regardless of if it classifies as a branch circuit, feeder, or service conductor.

Neutral does not count as "current carrying" in the following situations, which are a lot more common.
1. It is plausible for only the phase conductors to carry the current the full round trip path, and neutral is there for carrying imbalanced current. No matter what the imbalance. Note that even though neutral is carrying current in such a situation, we omit counting it as "current carrying", because any heat it generates, is heat a phase conductor isn't generating.
2. Neutral carries negligible load, because it is used for instrumentation & voltage sensing purposes.

 

[infinity]

I was told on commercial feeders and services example 3PH 4W 120/208 and 480/277 volt settings even if the neutral is considered current carrying I do not apply any adjustment factors for more than 3 current carrying conductors in a raceway.
Any comments or help?

This may help:

Neutral Conductors:
Here's some examples of when to count and not count the neutral as a current
carrying conductor or CCC:
3Ø- 208Y/120 or 480Y/277 volt system-different circuit types:
A) 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
B) 3 wire circuit w/ 2 ungrounded, 1 neutral = 3 CCC's
C) 4 wire circuit w/ 3 ungrounded, 1 neutral = 3 CCC's*
Notes:
A) A normal 2 wire circuit has equal current flowing in each of the circuit
conductors so they both count as CCC's.
B) In this circuit the neutral current will be nearly equal to the current in the
ungrounded conductors so the neutral counts as a CCC
C) In this circuit the neutral will only carry the imbalance of the current between
the three ungrounded conductors so it is not counted as a CCC, with an exception,
*if the current is more than 50% nonlinear (see below for NEC article 100
definition) then the neutral would count as a CCC.
1Ø- 120/240 volt system-different circuit types:
D) 2 wire circuit w/ 1 ungrounded, 1 neutral = 2 CCC's
E) 3 wire circuit w/ 2 ungrounded, 1 neutral = 2 CCC's
Notes:
D) A normal 2 wire circuit has equal current flowing in each of the circuit
conductors so they both count as CCC's.
E) In this circuit the neutral will only carry the imbalance between the two
ungrounded conductors so the neutral is not counted as a CCC.
Nonlinear Load. A load where the wave shape of the steady-state current does
not follow the wave shape of the applied voltage.
Informational Note: Electronic equipment, electronic/electric-discharge lighting,
adjustable-speed drive systems, and similar equipment may be nonlinear loads.

 

[Dennis Alwon]

On a 3 phase like you have you always count the neutral unless you have a full boat, i.e. 3 hots and a neutral, then you would not need to count the neutral unless the circuits are nonlinear load then you count the neutral