History of NEC 504

[natfuelbill]

Calling all NEC History Buffs!!!

I am looking to learn more on the history of Article 504.

When was it first introduced?
Major revisions?
In particular the history on 504.30 Separation of OS Conductors?

Thanks for sharing.

 

[Volta]

First year was 1990.

The text for wiring in raceways [504-30(a)(2)] was largely the same as today (2008), including exceptions 1 and 2.

The sub-section for wiring within enclosures [504-30(a)(3)] had less text, but referred to the raceway requirements/options (2" and secured, grounded metal partition, insulating partition, metal-sheathed, etc.) rather than listing them again.

The exception for other (open) wiring [504-30(a)(1)] listed type SNM along with the MC and MI. That method was removed in 1996.

The .25" clearance of 504.30(B)(3) was introduced in 2005.

 

[natfuelbill]

Thanks a bunch!