Grounding

[jamesdossett]

Article 250

Is it always required to have a fourth wire a sub-panel?
Grounding Conductor
Thanks
James Dossett

 

[ryan_618]

Yes, unless it is a seperate building or structure and 250.32(B)(2) is complied with.

Note that in the 2008 NEC that allowance will be gone.

 

[Pierre C Belarge]

The "4th wire" (equipment ground conductor) can be in the form of a metallic raceway...250.118.

 

[infinity]

You really cannot answer this question since too much information is missing. For example a 120 volt subpanel with the feeder in EMT will require only 2 conductors. A 3 phase subpanel in RNC will likely require 5 conductors. What kind of installation are you referring to?