problem

[shaw0486]

Ok i have a MCC that an engineer directed my company to feed a 120/208 3p 4 wire panel from. pulled the wire today and went to terminate and discovered that there is no neutral. Does anyone have any brilliant idea to make this work. Would a isolation transformer do it?

 

[raider1]

Yes, you could install a delta to wye transformer and create a grounded conductor, or if it is possible see if you can run a neutral in the feeder to the MCC.

Chris

 

[iwire]

Would a isolation transformer do it?

No, not an isolation transformer, a delta wye transformer as Chris mentioned.

 

[shaw0486]

have you ever installed a 208v delta-208v wye transformer and what exactly in a isolation transformer?

 

[shaw0486]

oeoeo bhh

 

[benaround]

shaw, is there a need for the grounded conductor at the MCC ?

 

[augie47]

Its' "above my pay grade" but there's a transformer configuration called a "zig-zag" that I've been told can do this more economically than a full size power transformer. Perhaps one of the transformer gurus here will expand on this. If not you might mention that to a transformer rep.

 

[iwire]

have you ever installed a 208v delta-208v wye transformer

No.

and what exactly in a isolation transformer

I always thought an isolation trans would be a straight single phase unit or a delta delta, but I could be mistaken. :smile:

 

[benaround]

shaw, is there a need for the grounded conductor at the MCC ?

Sorry, I read the post wrong.

 

[shaw0486]

does anyone know of a 208v delta to 208 y is this even possible

 

[shaw0486]

as does anyone have any info on a zigzag transformer i read about them in apprenticeship but that about all.

 

[infinity]

does anyone know of a 208v delta to 208 y is this even possible

I would guess that more than likely it would be a Wye/Wye transformer.

 

[Jim W in Tampa]

I got to ask why you would miss something like this. Enginer screwed up but you should caught it before pulling the wire.

 

[roger]

does anyone know of a 208v delta to 208 y is this even possible

Absolutely, any transformer manufacturer can accommodate you, just tell them what you want.

These are actually catalog items.

Roger

 

[nakulak]

are you sure that what you have is a delta configuration ? it may be that you simply need to pull in a grounded conductor from the source ? (rather than create a new SDS just to get a neutral that is already there) perhaps a little more information would be helpful.

 

[shaw0486]

well it is a wye that feeds the MCC but there is not enough room in the conduit to get a neutral in it

 

[nakulak]

did they pull a ground and is it metallic conduit ? (ie can you reidentify the gound as a neutral and use the conduit as ground ?)

 

[JES2727]

oeoeo bhh

uh-huh....

 

[shaw0486]

if it is 3 phase 208 no neutral i can use a delta wye even if the service coming in to the basement of the building is wye transformer right?

 

[roger]

Yes.

Roger