480 volt to ground service from utility

[jap]

The 480 volt single line is not jumping to both terminals. The one 480 leg would be on either H1 or H4 and the neutral would be on the other. I think it would work but after a phone call with Square D today, they say it won't work, but I think because they do not want the liability.

POCO came out and explained to us today that they have no issue with it but in order for the electronic meter to work we would need to install a jumper between the neutral and the 2nd (normally hot leg) line terminal of the meter so it would receive power.

Since Square D has decided to say no to us connecting this, we opted to also say no to protect ourselves from liability as well.

GC will now be paying POCO to install a 240/480 pad mount transformer immediately adjacent to the 480 single line transformer. This way we can just have them connect what we have and move on from this mess.

I about brought up the meter issue before also.
I was wondering how the meter would ever work with only 1 leg utilized.

Oh well,

Sounds like they're going to get you fixed up.

JAP>

 

[kwired]

The 480 volt single line is not jumping to both terminals. The one 480 leg would be on either H1 or H4 and the neutral would be on the other. I think it would work but after a phone call with Square D today, they say it won't work, but I think because they do not want the liability.

POCO came out and explained to us today that they have no issue with it but in order for the electronic meter to work we would need to install a jumper between the neutral and the 2nd (normally hot leg) line terminal of the meter so it would receive power.

Since Square D has decided to say no to us connecting this, we opted to also say no to protect ourselves from liability as well.

GC will now be paying POCO to install a 240/480 pad mount transformer immediately adjacent to the 480 single line transformer. This way we can just have them connect what we have and move on from this mess.

That transformer primary winding only cares to see 480 volts between H1 and H4, and could care less about what is or isn't grounded.

Yes somewhat rare to see a single phase 480 volt two wire source - but if you do have one and are going to ground it - it is going to be one leg or the other - either way one is 480 volts to ground.

A little more common to see 480 three wire corner grounded delta. You very well see 480 x 120 transformer connected to those systems and possibly could have one input leg be the grounded conductor - they work just fine. Seen many control transformers that work just fine on corner grounded delta, or even on high leg systems but still connected line to line.

 

[winnie]

GC will now be paying POCO to install a 240/480 pad mount transformer immediately adjacent to the 480 single line transformer. This way we can just have them connect what we have and move on from this mess.

If the POCO is installing a new padmount, why not a 120/240 to match the end use?

-Jon

 

[woodduder]

That transformer primary winding only cares to see 480 volts between H1 and H4, and could care less about what is or isn't grounded.

Agreed. I think it would work, but scared everyone. Square D told us we could not possibly have 480 on one leg to ground and we tried to explain to them that this was in fact a reality.

If the POCO is installing a new padmount, why not a 120/240 to match the end use?

Funny you should ask. We originally built a 120/240 service since we were told by FPL that the padmount was a 120/240. They came out 2 week ago to hook us up and realized it was a (we were told by FPL) 240/480. So then we rebuilt the service with several thousand dollars of equipment.

Then they came out Monday to hook us up and opened the transformer and said sorry it is not a 240/480, it is a straight 480 single line to ground. And so we have already built all the gear and the GC office trailer is about 300 feet away from the service so we do not want to tear it all down and rebuild once again.

I can send 100 amps of 480 a long darn way on #1 aluminum (and it is already installed), but if I change to 200 amps of 240 I have to redo it all at another huge expense.

 

[kwired]

That transformer primary winding only cares to see 480 volts between H1 and H4, and could care less about what is or isn't grounded.

Agreed. I think it would work, but scared everyone. Square D told us we could not possibly have 480 on one leg to ground and we tried to explain to them that this was in fact a reality.

If the POCO is installing a new padmount, why not a 120/240 to match the end use?

Funny you should ask. We originally built a 120/240 service since we were told by FPL that the padmount was a 120/240. They came out 2 week ago to hook us up and realized it was a (we were told by FPL) 240/480. So then we rebuilt the service with several thousand dollars of equipment.

Then they came out Monday to hook us up and opened the transformer and said sorry it is not a 240/480, it is a straight 480 single line to ground. And so we have already built all the gear and the GC office trailer is about 300 feet away from the service so we do not want to tear it all down and rebuild once again.

I can send 100 amps of 480 a long darn way on #1 aluminum (and it is already installed), but if I change to 200 amps of 240 I have to redo it all at another huge expense.

You talked to wrong person at Square D - it is very possible to have 480 volt two wire and ground one side of it. Might be something not seen all that often but any two wire system that is grounded will have full system voltage to ground.

I believe it has even been discussed on this forum before that in some situations you can step up say a 120/240 to 480 volts, ground one lead and only run a two wire feeder to another structure (one of which will be a grounded conductor) then step back down. Can't be any other conductive paths outside of earth between the two points. This usually done because of long runs and voltage drop reasons.

Is this 480 volt two wire service already serving some other load and they are adding your temp service to it?

If so does it have the ability to serve your load? Sounds like street/area lighting is a good possibility for what is already being served, could be limited source, like only 5 or 10 kVA transformer. Good news is maybe you won't have much load when the lighting is operating and they are fine with that.

 

[jap]

I don't think they talked to the wrong person a Sq. D.

I think if the wording of explaining what voltage they were actually dealing with was a little more clear to begin with, it wouldn't have caused so much confusion.

JAP>

 

[kwired]

I don't think they talked to the wrong person a Sq. D.

I think if the wording of explaining what voltage they were actually dealing with was a little more clear to begin with, it wouldn't have caused so much confusion.

JAP>

Possible. I thought he had something different until several posts into the thread.

 

[jap]

Me too.

But I agree, as long as you can get 480 across H1 and H4 somehow, the magic ought to happen.

JAP>

 

[kwired]

Me too.

But I agree, as long as you can get 480 across H1 and H4 somehow, the magic ought to happen.

JAP>

Absolutely, even an ungrounded source will still make this work as long as the input sees ~480 volts.