400A 3Ø

[Little Bill]

It is typical to have a 400A (320A) single phase service. Usually come off the meter to (2) 200A panels. My question is if you have a 3Ø 400A service, could you come of the meter to a 200A 3Ø panel and also to a 200A single phase panel?

 

[infinity]

I don't see why not but the question is why do you want to? Add one conductor and get a big increase in capacity.

 

[electrofelon]

Might make more sense if it's a high leg delta service. I almost did that once where the client wanted a backup genny: 3 phase panel for the few three phase things and larger non critical loads then a single phase set for a single phase ats/panel for most everything else.

 

[Dennis Alwon]

I would think if it is 3 phase 400 amps you will need a CT and not come off the meter. Someone will probably say I am wrong but I believe around here there isn't a 400 amp 3 phase meter.

 

[jaggedben]

I've seen a number of 400A single phase services, all residential. Most have (2) 200A main breakers, with one integrated 200A panelboard and another breaker for feeding a remote subpanel. But a couple have been a 400A panelboard.

 

[electrofelon]

I would think if it is 3 phase 400 amps you will need a CT and not come off the meter. Someone will probably say I am wrong but I believe around here there isn't a 400 amp 3 phase meter.

I think In theory it all comes down to what the load calc is and if it falls within the 320 continuous 400 non continuous rating of a class 320 socket. That said there are some utilities who do not allow a 320 socket for commercial - anything over 200 is instrument metered.

 

[Cow]

It is typical to have a 400A (320A) single phase service. Usually come off the meter to (2) 200A panels. My question is if you have a 3Ø 400A service, could you come of the meter to a 200A 3Ø panel and also to a 200A single phase panel?

Yes.

I don't see why not but the question is why do you want to? Add one conductor and get a big increase in capacity.

I agree. If you went to the trouble and expense to install a 3 phase service at least give the customer 3 phase panels...

 

[brantmacga]

I would think if it is 3 phase 400 amps you will need a CT and not come off the meter. Someone will probably say I am wrong but I believe around here there isn't a 400 amp 3 phase meter.

Yes there is a 400A 3 phase meter.

Some Utilities I work with use a trans-socket at 600A, and some use a CT meter on anything above 400A.


This is a 400A 3 phase delta service we installed a few weeks ago, and is setup exactly as OP described; it’s back-to-back with a single phase and three phase loadcenter.

Sent from my iPhone using Tapatalk

 

[Little Bill]

To answer some of the questions.

POCO won't have to CT meter it.

Customer only has a single machine that needs 3Ø
The HVAC will also be 3Ø
The rest of the loads are single phase, the majority being single pole 120V
So for convenience, the single phase panel would be added, especially if it's a high leg.
Customer also wants several extra spaces for future needs.

Haven't heard for sure if I will have a Delta high leg or 208Y/120. The POCO engineer said he would get back to me and let me know.


I can get a 200A 3Ø panel with minimum spaces and a 200A, 40 space single phase panel cheaper than one large 3Ø panel.

And yes, the customer was told that a VFD or phase converter for the 3Ø machine would be cheaper than the 3Ø service. The HVAC could be changed to a single phase as it's not been installed yet.
Customer is dead set on the 3Ø.

 

[kwired]

Might make more sense if it's a high leg delta service. I almost did that once where the client wanted a backup genny: 3 phase panel for the few three phase things and larger non critical loads then a single phase set for a single phase ats/panel for most everything else.

That was my thought - can be really convenient on high leg delta systems where there is limited three phase loads, but at same time you still limited to 200 amps on the single phase panel.

I would think if it is 3 phase 400 amps you will need a CT and not come off the meter. Someone will probably say I am wrong but I believe around here there isn't a 400 amp 3 phase meter.

Those meters are out there, there just isn't a lot of POCO's that use them, and often want to go to CT metering if 320 amp socket isn't going to be enough.

To answer some of the questions.

POCO won't have to CT meter it.

Customer only has a single machine that needs 3Ø
The HVAC will also be 3Ø
The rest of the loads are single phase, the majority being single pole 120V
So for convenience, the single phase panel would be added, especially if it's a high leg.
Customer also wants several extra spaces for future needs.

Haven't heard for sure if I will have a Delta high leg or 208Y/120. The POCO engineer said he would get back to me and let me know.


I can get a 200A 3Ø panel with minimum spaces and a 200A, 40 space single phase panel cheaper than one large 3Ø panel.

And yes, the customer was told that a VFD or phase converter for the 3Ø machine would be cheaper than the 3Ø service. The HVAC could be changed to a single phase as it's not been installed yet.
Customer is dead set on the 3Ø.

If it is a high leg delta - more details may be needed to decide if one wants the third phase at both panels, if it is 208/120, I'd probably go with three phase panels for both regardless.

 

[meternerd]

I would think if it is 3 phase 400 amps you will need a CT and not come off the meter. Someone will probably say I am wrong but I believe around here there isn't a 400 amp 3 phase meter.

True that there is a CL 320 FM 16S three phase meter available, supposedly intended for commercial, but my experience is that many utilities don't allow them. Even on residential, it's likely they require CT's. It may have to do with reducing inventory of different types of meters. That's why we didn't allow 'em.