ECN Forum Forums Code Related Discussion NEC & other Code issues NEC historians wanted

electure Wrote:
"George, you brought up a very good point.
ALWAYS, yes ALWAYS, test disconnects when you shut them off to make sure they're wired correctly. I've run across quite a few that were wired backwards, and this leaves the fuses HOT! (& I'm still here to talk about it)."

One other precaution is to make sure you check phase to phase as well as phase to ground. Remember that the US NEC does not require Delta transformers that do not have a center tapped phase to be grounded.

I was on a ladder, caulking our conduit holes, when I saw the air conditioning tech. open the disconnect using the interlock bypass. He proceeded to test from phase to ground on each phase. I screamed at him as he reached toward the fuses with his bare hand. He jumped about a foot and cussed me out. I told him to test phase to phase and when he did he turned very pale. The transformer supplying the Air conditioner and refrigeration was 240 volt Delta connected on the secondary side. There was no ground reference on the secondary wiring. Even 480 volt, delta connected, transformers can be without ground reference.

What I never thought to ask him was why he had used the interlock bypass to open the dammed disconnect in the first place.
--
Tom

I believe that the following image helps to answer the question.

Joe,
I've been changing my old shop bldg out for a new shop bldg, but somewhere I have old switches you can actually see the knife in, of course they are porcelain, when I find 'em, I'll send a snap.

George:
Well, I have no idea what raw nerve I might stumble upon (re black, red, blue), but I apologize for trying to upset the apple-cart....

[Changes subject rapidly]

Those push-button operated switches look interesting. Does anyone know what sort of period they were manufactured/installed in?

In some old 1930s U.S. movies and newer "period" shows (e.g. The Waltons), I've also seen what appear to be rotary light switches, surface mounted. Or have I misinterpreted what I saw?

Paul,
very observant! yes the old K&T rotaries were suface mount & backwired.

George,
380-6(C), now 404.6(C), THAT'S THE ONE ! , and because of it, all the smaller stuff just followed suit.

Ah, they were used with K&T. That explains what looked like two single cables run down the wall clamped into some sort of straps a couple of inches apart.

Took me a while to figure out K&T, as it wasn't used over here.

These types of switches are still made and used. People try to keep the houses historically accurate. I don't know if the internal mechanisms work the same but they look the same from the outside. Also they come in dimmer type where the push button turns. I think one company that makes them is in Oregon somewhere.

Some manufacturers here are selling replicas of our old 1920s-style "tumbler" switches -- Round toggles with a domed polished brass screw-on cover.

They're not cheap though: I've seen them as much as £15 ($22) each in some places.

It's ironic that 30 years ago the genuine articles were being stripped out of old houses and thrown away as junk.

photo by George Corron and his story

Joe,

Don't know that there is much of a story. It is just about how I got my 7 year job at the prison though.

Some of my neighbors, when I was in business for myself, lived in the prison supplied housing.

The prison was 100 years old when they shut it down, and when it was built, it was
in a very rural location, so the 'Chief' tradesmen, boiler, plumbing, electrical, etc. were supplied with on site housing to be available in an emergency, it was very nice housing of the day, but like the rest of
the place, was allowed to deteriorate in the last years.

Maintenance was ..... eh, scattered at best, and since they knew me, they would ask if I
would come look at things before calling the maintenance staff there.

I did lots of little favors for them, and during the "depression" of 90, they offered me several jobs, and I finally accepted the job in 92 taking care of the high voltage shop and generators.

I found several of these original switches, and kept a couple of them because they were
interesting.

Often found them arcing like the devil, naturally encased in dust and other flammables, could've been disastrous.

George



[This message has been edited by Joe Tedesco (edited 12-16-2001).]