Grounded Conductor

[cooldad]

Am I required to use a neutral conductor in a 3ph wye (120/208) feeder that will be used to feed a bank of airconditioning units? - no other loads will be used from this sub-panel. grateful if you could comment on this.

Thanks

 

[charlie b]

If your loads do not require a neutral wire, then the feeder or branch circuit need not contain one. Welcome to the forum.

 

[LarryFine]

Welcome to the forum!

Am I required to use a neutral conductor in a 3ph wye (120/208) feeder that will be used to feed a bank of airconditioning units? - no other loads will be used from this sub-panel. grateful if you could comment on this.

Not if the neutral will not be needed by any loads.

 

[paul]

Why was the other duplicate post (located in NEC section) deleted when this is an NEC rule issue and not an engineering/design issue?

Just curious

 

[boboelectric]

How about the need of a 120 volt receptacle for servicing? Then you would want the neutral.

 

[LarryFine]

Why was the other duplicate post (located in NEC section) deleted when this is an NEC rule issue and not an engineering/design issue?

Why ask why?

Just curious

Good a reason as any.

 

[LarryFine]

How about the need of a 120 volt receptacle for servicing? Then you would want the neutral.

True. However:

... no other loads will be used from this sub-panel.

So, it's presumed that any required receptacle will be supplied elsewhere.

 

[infinity]

Why was the other duplicate post (located in NEC section) deleted when this is an NEC rule issue and not an engineering/design issue?

Just curious

Because it is a design issue.

You may want to have a neutral present for future loads or you may not. One design method will cost less than the other.

 

[roger]

And another reason was that this thread already had activity.

Roger

 

[mcclary's electrical]

Am I required to use a neutral conductor in a 3ph wye (120/208) feeder that will be used to feed a bank of airconditioning units? - no other loads will be used from this sub-panel. grateful if you could comment on this.

Thanks

If you do that, the subpanel, and breakers cannot be slash rated.

 

[Pierre C Belarge]

If you do that, the subpanel, and breakers cannot be slash rated.

Because one is not using the grounded conductor of a Solidly grounded Wye System, does not change the fact the system wiring to the subpanel is still a Solidly grounded Wye system.


Take a look at the second paragraph of 240.85. The issue is the ungrounded conductor in relation to ground, not to the grounded conductor.

 

[JdoubleU]

If you do that, the subpanel, and breakers cannot be slash rated.

What do you mean by slash rated

 

[LarryFine]

What do you mean by slash rated

Some breakers are rated 120/240v, and some 240v. The former relates to line-ground voltage, and the latter to line-line voltage.

The rating here needs to be greater than 120v line-to-ground, at least for any 2- or 3-pole breaker connected to the high leg.