Drastic change: 410.73 (G)

[iwire]

Re: Drastic change: 410.73 (G)

Originally posted by infinity:
A neutral at a fixture with a de-energized circuit conductor poses no safety threat.

Actually due to voltage drop on the neutral of the circuit between the panel and the point the circuit splits up can raise the potential of the neutral at the 'dead' fixtures.

That said I doubt it is much of a safety threat no more than the neutral bar in a sub panel.

 

[cselectric]

Re: Drastic change: 410.73 (G)

Originally posted by infinity:

Without this switching arrangement, a maintenance tech can believe he is totally safe because he killed a circuit, and then get blown off of his ladder by the grounded conductor.

This would not happen if the circuit were de-energized and the electrician were only working on the fixture ballast. The point in the multiwire branch circuit where to the neutral becomes a safety issue is the point at which it is shared with other circuits. A neutral at a fixture with a de-energized circuit conductor poses no safety threat.

Unless you are dealing with rows of lights inwhich multiple circuits exist (feed through wiring.) Then the grounded conductor splice at the ballast might well be in line with other lights and/or other circuits. Maybe that is a stretch, but what other reason would they have for wanting the grounded conductor switched?

 

[macmikeman]

Re: Drastic change: 410.73 (G)

I have worked in a building that had flourescent lights that came equiped with a connector arraingement sort of like a molex plug. A squeeze pull released both the hot leg and the grounded conductor from the circuit, making a ballast change out on a live fixture at least a little safer. Many times I have run across old wire nuts that the plastic cracked and is just barely hanging together. I find this condtion mostly on 277 v lighting systems. Must be overheating related, but anyway 277 v to ground is more than I like to shake hands with, or be near when it contacts a grounded metal fixture. I do not care if others here wish to call some of us stupid, I stand firm in saying this is a really good code upgrade. Some situations will have us working on live equipment at times. None of us like it but none of us like collecting welfare checks either.

 

[bphgravity]

Re: Drastic change: 410.73 (G)

Originally posted by macmikeman:
Some situations will have us working on live equipment at times. None of us like it but none of us like collecting welfare checks either.

No, but your wife will be when you end up dead. I hope you have good life insurance.

 

[LarryFine]

Re: Drastic change: 410.73 (G)

Originally posted by cselectric:
Those disconnecting pins do nothing to kill power at the ballast, which is what is actually being required.

They most certainly do. The sprung end sockest are single conductor each, and connect to the red or blue ballast wires; those do not p[rovide any disconnecting.

However, the unsprung end sockets have two contacts each; the white conductor is broken when one tube is removed, and the black one is broken when the other tube is removed.

The pin itself bridges the incoming conductor to the ballast conductor. Thus:

Edited to add: Sorry, Don, I responded befor reading page 2.

[ September 10, 2005, 10:48 PM: Message edited by: LarryFine ]

 

[augie47]

Re: Drastic change: 410.73 (G)

A few comments , if I may,
the initial "shock" (no pun intended) of this new requirement lessens some when you read the numerous excecptions and note that single pin lamps that disconnect the line (as shown above)are also not included.

Mr. Lowrance, of CMP 18, advised one of the reasons for the delayed enforcement to 2008, was to allow mfgs. to design this into their fixtures, which is the expected route.

I think a lil added benefit is that the bravehearts who like to work them live will now turn off power to the new electronic ballasts which don't seem to enjoy the arcin' and saprkin' associated with a live reconnect.

 

[tom baker]

Re: Drastic change: 410.73 (G)

At the NFPA annual meeting the mfgs were against this new rule.
My prediction is once the product is avaialable, the manufactures will promote the advantages of the product:
1. Less labor to change a ballast
2. Safety
3. Change mfg A ballast to mfg B ballast easily.

I envision some type of a mollex plug that would be part of the ballast case. A wiring harness would plug in to the ballast.
It would be stanard between manufactures to allow interchanging ballasts