NEC question

[Bill Smith]

In what version of the NEC was the requirement for isolated neutrals and grounds in sub panels first mentioned?

[Paul W. Abernathy]

Good question Bill....let me say this, I have a 1993 NEC and it has the requirement in it so it was atleast back before the 1993 NEC.

250.61(b) Load-Side Equipment.

A grounded circuit conductor
shall not be used for grounding noncurrent-carrying metal
parts of equipment on the load side of the service disconnecting
means or on the load side of a separately derived system
disconnecting means or the overcurrent devices for a separately
derived system not having a main disconnecting means.

[Bruce A. King]

I read somewhere that it was covered way back to the 1940's by the catch all code phrase "follow the manufactures instructions".

[Bill Smith]

Thanks guys.