Installing sub-panel

[Davebones]

Panel is a 480v ,3 phase ,200 amp main breaker . Will be using 3 phase only ,no neutral needed . Contractor says because nameplate says 3 ph 4 wire we need neutral or inspector might have a problem with it. Would inspector see thia as a problem ???

 

[raider1]

The inspector should not have a problem with it.

There is no NEC requirement that a grounded conductor be brought to a panelboard that does not have any loads that require a grounded conductor.

Chris

 

[Davebones]

Thanks for the info . I couldn't believe this would be a problem .

 

[mcclary's electrical]

There will be a problem if you put slash rated breakers in it

 

[Cold Fusion]

There will be a problem if you put slash rated breakers in it

Post 1 makes it sound like the system is 480V grounded Y. They just are considering not taking the neutral to this panel. If so, why are slash breakers prohibited?

cf

 

[Davebones]

Just Siemens BQD breakers . 2 pole or 3 pole only .

 

[jumper]

Just Siemens BQD breakers . 2 pole or 3 pole only .

Okay, I am tired and confused. Would not using 2 pole breakers in a 3 phase panel need a neutral unless it was balanced according to amps per phase conductor?

 

[Cold Fusion]

Okay, I am tired and confused. Would not using 2 pole breakers in a 3 phase panel need a neutral unless it was balanced according to amps per phase conductor?

If the load does not take a neutral, it is just a 480V single phase load, no neutral current

cf

 

[Jim W in Tampa]

No need for neutral if not using it. Is not a bad idea to have one for future items that might need 277 but not required on 480 or 240 systems

 

[mcclary's electrical]

Post 1 makes it sound like the system is 480V grounded Y. They just are considering not taking the neutral to this panel. If so, why are slash breakers prohibited?

cf

You could not put a 277/480 volt breaker in this panel legally

 

[tkb]

There will be a problem if you put slash rated breakers in it

Why would this be a problem.
It it is a 480/277v source, and you do not pull the neutral, you still have the same voltage to ground as you would have with a neutral.

Just because you don't pull a neutral, it doesn't make it a delta source.

 

[Cold Fusion]

You could not put a 277/480 volt breaker in this panel legally

Doesn't rally change my question any.

Why is it a problem?
Why is it illegal?

An if you are planning on telling us it is unsafe - Why is it unsafe?

cf

 

[LarryFine]

You could not put a 277/480 volt breaker in this panel legally

Sure, you could. The first number is the max line-to-neutral (ground) voltage, the second is max line-to-line voltage.

The system's line-to-ground voltage does not change with the presence or absence of a neutral in a particular panel.

A corner-grounded Delta would be a different story, of course.

 

[mcclary's electrical]

Sure, you could. The first number is the max line-to-neutral (ground) voltage, the second is max line-to-line voltage.

The system's line-to-ground voltage does not change with the presence or absence of a neutral in a particular panel.

A corner-grounded Delta would be a different story, of course.

Ok, you convinced me. :grin:

 

[LarryFine]

Ok, you convinced me. :grin:

"Now I don't have to stab you."​