Size of grnd cond.

[navyman]

How do I go about determining the equipment ground conductor size? I'm wiring a 30 hp phase converter supplying two CNC machines. Machines are supplied with #6 copper from converter. Converter is fed with #4 copper on a 125a bkr.

 

[480sparky]

Start in Part VI of Art. 250.

250.122 is where you want to go.

 

[Dennis Alwon]

How do I go about determining the equipment ground conductor size? I'm wiring a 30 hp phase converter supplying two CNC machines. Machines are supplied with #6 copper from converter. Converter is fed with #4 copper on a 125a bkr.

250.122 will give that info. Breaker size determines the egc. 125 amp breaker needs a #6 egc.