Need to derive neutral from staright 3phase

[billklus]

I want to feed a 480/277 volt small emergency lighting panel from a nearby 480/277 volt dist. panel. The problem is there is no neutral available in the dist. panel. Can I feed an isolation transformer and derive a neutral through XO bond to feed my sub panel Legally???? There is no other feed anywhere close..... Panel I'm installing is only a 30 amp main.

Thanks......

 

[raider1]

Yes, you can feed an 1 to 1 ratio delta wye isolation transformer and ground the XO tap to create a grounded (neutral) conductor to supply a 480/277 volt panel.

How hard would it be to bring a neutral from the original 480/277 volt source?

Chris

 

[iwire]

How hard would it be to bring a neutral from the original 480/277 volt source?

Piece of cake if I can tie wrap it on the outside of the feeder conduit. :smile:

 

[raider1]

Piece of cake if I can tie wrap it on the outside of the feeder conduit. :smile:

I was just throwing that out as a possible solution to the problem, it might be cheaper than purchasing an isolation transformer.

Chris

 

[billklus]

To pull an upstream neutral to this downstream point would suck major!!!!! Lowest bidder definitely installed this system

 

[brian john]

Yes, you can feed an 1 to 1 ratio delta wye isolation transformer and ground the XO tap to create a grounded (neutral) conductor to supply a 480/277 volt panel.

How hard would it be to bring a neutral from the original 480/277 volt source?

Chris

It is really not a one to one 480 delta to 480/277 is 1.732 to 1

 

[raider1]

It is really not a one to one 480 delta to 480/277 is 1.732 to 1

True.

Chris

 

[LarryFine]

Piece of cake if I can tie wrap it on the outside of the feeder conduit. :smile:

Well, heck, just use the conduit.

 

[beanland]

Required Neutral

Required Neutral

If I remember right, a 480Y/277V service means that the service is wye with the center of the wye grounded. I believe NEC requires the grounded conductor brought to the service, even if there is nothing hooked to it. You may be able to get the neutral at the main service.

If there is no neutral from the service, it would have to be 480V 3-phase 3-wire ungrounded to meet NEC.

 

[Pierre C Belarge]

I want to feed a 480/277 volt small emergency lighting panel from a nearby 480/277 volt dist. panel. The problem is there is no neutral available in the dist. panel. Can I feed an isolation transformer and derive a neutral through XO bond to feed my sub panel Legally???? There is no other feed anywhere close..... Panel I'm installing is only a 30 amp main.

Thanks......

If there is no neutral, the panel is not a 480Y/277 panel.

300.3(B) Requires all of the conductors of a circuit to be run together.

It sounds like you will need to install a feeder to a transformer and use the secondary to develop a neutral conductor.

 

[quogueelectric]

I dont know why you would need an isolation xformer just a 480 delta to 480 wye if they make one which I think they do.

 

[claytazdaisy]

its because its not a 480/277v. just a 480. you have to use a isolation transformer to pick up your nuetral.

 

[LarryFine]

I dont know why you would need an isolation xformer just a 480 delta to 480 wye if they make one which I think they do.

Actually, that is an isolation transformer.

 

[billklus]

If there is no neutral, the panel is not a 480Y/277 panel.

If there is no neutral, the panel is not a 480Y/277 panel.

My mistake..... What I'm feeding from is a straight 480 V 3Ph. Dist panel.... I am complete with the install and used a Iso. Xfmr. and it worked out great!!! Customer was understanding with the whole thing.....