Reduced Neutral in 3 Phase System

[jfpe]

I'm sizing wires for a 3 phase 45 kW inverter in a photovoltaic system. The inverter only requires the 3 phase conductors, but the kWh meter we're installing requires a neutral. Does the neutral need to be the same size as the phase conductors? I can rationalize making the neutral smaller, since it's only for the meter and won't carry any current, but I can't find an NEC reference to support a reduced neutral.

Thanks,
John

 

[wareagle]

You might be able to reduce the size. See 220.61
230.42 A,B,C and 250.24C 1,2 and 3.

 

[sslobodan]

1/3 of mains size can be allowed for grounding. Considering your reference point should be ground, than you should create neutral and grounding from grounding system and never to connect them on some another spot in a circle. If your kWh meter requires neutral, you should look if his prime is connected in star or delta. Otherwise you might fry him down.