120/240 high leg

[eds]

When you have a single phase service drop as part of a 3 phase 120/240 high leg service arrangement do you calculate that single phase part of the service at 240v or at 240*1.732

 

[ptonsparky]

I would use 240. It is a single phase load.

 

[electrofelon]

When you have a single phase service drop as part of a 3 phase 120/240 high leg service arrangement

I don't understand what that means. Do you mean you have a single phase service that POCO is supplying off a Delta bank?

 

[eds]

Yes, 600 amp ct service with a 200 amp 3 phase riser and a 400 amp single phase riser

 

[electrofelon]

Yes, 600 amp ct service with a 200 amp 3 phase riser and a 400 amp single phase riser

Ah ok.. That is actually kinda interesting, as far as whether it is a 230.40 exception #2 or two different services using the "different characteristics" clause. Are the service disconnects grouped?

 

[eds]

Yes

 

[don_resqcapt19]

Sounds like a single service with two service disconnects to me. That is fairly common high leg services. Reduces the risk of 120 volt loads being connected to the high leg.

 

[ptonsparky]

Yes, 600 amp ct service with a 200 amp 3 phase riser and a 400 amp single phase riser

You have two services. You answered your own question.

 

[eds]

So one more questions, I need to add another 200 amp 3 phase disconnect to this same drop. I have 3 phase rooftop and then the rest will be single phase load. Do I do a separate calculations for the three phase and single phase loads. Single phase loads our for a cafe equipment

 

[ptonsparky]

So one more questions, I need to add another 200 amp 3 phase disconnect to this same drop. I have 3 phase rooftop and then the rest will be single phase load. Do I do a separate calculations for the three phase and single phase loads. Single phase loads our for a cafe equipment

Let the POCO know how your load is changing. Is the existing 3 phase service large enough to handle this load or are you adding another 3 Ph service disconnect?

 

[ptonsparky]

Forget the 3 phase load for now. Calculate the single phase service. What is it? xxx amp.

Forget the 1 phase load. It doesn't matter. Calculate the three phase load. What is it?
yyy amp.

Tell the POCO each of those loads. Separately. You have xxx amp single phase. You have yyy amp three phase.

 

[ptonsparky]

It is up to the POCO how they serve you.

 

[eds]

Let the POCO know how your load is changing. Is the existing 3 phase service large enough to handle this load or are you adding another 3 Ph service disconnect?

Adding a additional 3 phase 200 amp disco to handle the new 3 phase load and the new single phase load