3 Phase < 600Vac system. NEC Question

[AggieDave]

Situation:
Mixed Use Building - Retail/Multifamily
3-Phase 208V Service - Master Meter
* 3rd party electronic submetering for retail and MF occupants.

Is there a article in the National Electric Code that would prevent setting a mixture of 3 phase panels and 1 phase panels witin the same system?

My first thought was that as long as the color coding of the conductors is consistent, it is not a problem. With the 3 Phase panels, the colors would be per NEC or ordinance and the single phase panels would just be 2 of the 3 colors.

i.e.

Phase A - Red
Phase B - Blue
Phase C - Black

* All three would be present in the 3-phase panels.

Phase A - Red
Phase B - Blue

Phase B - Blue
Phase C - Black

Phase A - Red
Phase C - Black
* Three variations of the single phase feeders.

** Please excuse the colors if they are not correct, I am writing off the top of my head.

In my jurisdiction, branch ccts are not required to be color coded within dwellings. So it does not seem to be an issue. The only remaining requirement was to achieve NEC and Utility Co required balance between the phases.

This configuration is used all the time in multifamily, however, in this jurisdiction, there is a poorly written ordinance that allows the change from 3phase to 1phase at modular metering only.

Ultimatly, this project is considered by the utility and the building code as a commercial building and thus the reason for my question:

Can you have a mixture of 3phase and 1phase panels within the same system within a commercial building.

Thanks for any thoughts
D

 

[davidbeach]

No NEC reason why not. Talk to your AHJ.

 

[AggieDave]

That is what I thought. I have talked to the AHJ. They are just crazy. They take the approach "if it is not in code, it is not allowed". Very frustrating.

-D

 

[waross]

Beware of metering. You will not have single at your single phase panels. You will have two of three phases at your single phase panels. Your basic residential meters will not meter properly. Four jaw meter bases are not suitable. Your meters must have a neutral jaw and 120V potential coils.
Four jaw residential meters have 240V potential coils. The meter assumes that the line to neutral voltages are balanced at 120 Volts. These meters will meter line to line loads at 208 volts but have serious issues with 120 Volt loads.
The potential coil will only see 208 volts and will assume that the line to neutral loads will be at 104 Volts rather than 120 Volts.
There will be a phase angle error between the current coils and the potential coils with line to neutral loads.
Check with the third party sub-metering authority as to what configuration of meter bases are required.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[AggieDave]

Bill,
The project is not set up for modular metering. It is late and I failed to mention that it is 3rd party electronic ferrous loop metering for the residential occupancies. i.e. it is master meter (3-phase). The single phase (I realize that it is really 2 phases) originates from a distrubution panel board (3phase) and 2 poles are taken to each dwelling.

Maybe that is the point that I need to hammer home. It is still a 3-phase system, I am just extending 2 of the 3 to the dwellings thus the reason for staying consistent with the 3-phase coloring.

 

[AggieDave]

The 3rd party manufactures a 208v, meter specifically for this purpose.

http://www.imsmeters.com

- example

Thanks for the warning though. I will be sure to verify.

-D

 

[magoo2]

They used to refer to that as a network meter which is used for single phase services on a 208 V supply.