Isolated ground

[sirbph]

Hello,

We got a call from a contractor who is confused about an isolated ground system schematic diagram we've given him. The diagram shows the isolated ground connected to a panel and goes back to a transformer w/ an isolated ground bus. The isolated ground is for a sound system as required. Is this correct and where can I find it in the NEC? Since I haven't worked on this design and new to the matter I need a little help.

 

[bphgravity]

See sections 408.40 and the Exception that sends you back to 250.146(D).

 

[GalwayElectric]

250.146 (D) "Exception, so as to terminate within the same building or structure directly at an equipment grounding conductore terminal of the application derived system or service"

Bond with the xo on your transformer.