Explaining the National Electrical Code

[Joe Tedesco]

Old book on the NEC

[:-bigeyes

http://books.google.com/books?id=Mb9JAA ... yASUy6nmDA

[AHI in AR]

In describing this book, I'd put "old" in caps, and BOLD, if it was up to me. Pretty cool, nonetheless.

I did learn that an approved insulator was Alberene stone (Apparently from Virginia.) Anybody ever heard of that? (Kibbel, you don't count. We all know you've heard of it...and probably used it!)

Admittedly, I cheated and scanned thru most sections -- the Alberene reference was at the end.

[Jim Katen]

Thanks for posting that Joe. It's very entertaining reading.

Some of my favorite quotations from the commentary:

Further, where machines of very high E.M.F. are used, a damp floor or a poorly insulated machine may endanger the life of the attendent, or at least discourage him from properly attending to the machine. (In those days, E.M.F meant electro motive force, what we now call voltage.)

(Concerning "oily waste") It's habit if indulging in spontaneous combustion, especially when it has a good chance to set fire to something else, is too well known to insurance men to call for comment.

On the origin of bus bars: Where several dynamos are run in a power or incandescent lighting plant, it is common practice to lead all the circuits from the dynamos to one pair or set of conductors upon the switch board, and from these conductors to lead off all the lighting or power circuits. These main conductors are usually so large that flat copper bars are used instead of wires. These bars, as they carry the entire load of the plant, are called "bus bars."

In describing the function of a rheostat, they observe that "A rheostat corresponds to the throttle on a steam engine." What a wonderfully quaint explanation.

I'm also struck by the lack of standardization that existed back then. This code is trying to address systems where you've got both public power generation and private generation. There were buildings with both AC wiring and DC wiring (the AC for lighting and the DC for motors). Voltages were all over the map with "resistance boxes" complicating matters.

Also, they didn't seem to have decided yet what to do about grounding. There's nothing like an Article 250 such as we have nowadays.

I can see why the insurance industry was eager to set out some kind of rules to regulate this highly dangerous new technology.

- Jim Katen, Oregon