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Is that ballast Bad? #45499 12/01/04 02:50 AM
Joined: Dec 2004
Posts: 78
Cinner Offline OP
Is it safe to say that when a ballast is blackened (burnt like) or leaking a black tar like substance that it is no good any more and needs replacement. I have noticed that when the ballast looks like that they still work, but do they work less efficiently?


Work Gear for Electricians and the Trades
Re: Is that ballast Bad? #45500 12/01/04 04:00 AM
Joined: Oct 2004
Posts: 803
mxslick Offline
If any ballast shows leakage of more that say a drop of tar where the wires enter, or if it appears that the label is burnt (not just yellowed) then it should be considered bad. My experience has been that ignoring those signs will eventually result in a total meltdown with lots of smelly smoke!! I've seen this happen even with "P" rated ballasts!

For those not familiar, "P" rated ballasts have a built-in thermal protector which is supposed to kill the input power before it completely burns up. But a fire is still possible if any of the following happen:

1) The fixture is left on and cycles on and off from the protector. It will still build up lots of heat, and possibly causing:
2) Failure of the thermal protector [contacts weld closed] or:
3) On 240v ballasts, some thermal protectors open only one of the incoming lines. If the ballast has a short to ground, current can still flow from the other hot leg and smoke it. (Haven't seen 277 ballasts fail like this, IIRC 277 is a phase-to-grounded[neutral] voltage.)

In short, if it looks bad, change it!! Cheap insurance against possible violent failure.

[edited for spelling]

[This message has been edited by mxslick (edited 12-01-2004).]

Stupid should be painful.
Re: Is that ballast Bad? #45501 12/01/04 09:44 AM
Joined: Nov 2004
Posts: 80
Bert66 Offline
I have not personally use one but I hear that there is a ballast test on the market. But I normaly follow the same rule that if it looks bad replace it.

Re: Is that ballast Bad? #45502 12/01/04 09:53 AM
Joined: Jan 2003
Posts: 4,391
iwire Offline
I bought a ballast tester from Greenlee.

A waste of money IMO.

First to use it you need new ballast of exactly same type and brand ballast of the one you want to test.

Then you have to unwire the one to be tested and compare readings from the old one to the new one.

At the labor rate of an electrician around here it is more cost effective to just replace the ballast in the first place after trying new lamps and taking a look at the connections.


Bob Badger
Construction & Maintenance Electrician
Re: Is that ballast Bad? #45503 12/03/04 12:22 AM
Joined: Dec 2004
Posts: 78
Cinner Offline OP
Will they run less efficiently when they are leaking mollasses like substances?

Re: Is that ballast Bad? #45504 12/03/04 03:13 AM
Joined: Oct 2004
Posts: 803
mxslick Offline
Sorry, I missed the efficiency question in my first post. [Linked Image]

Based on the fact that the leakage usually indicates excessive temperature mainly caused by some internal fault, it very likely that the ballast is inefficient and drawing more than rated current. You could check actual current draw against the marked rating, assuming the label is still readable.

Such a ballast would tend to cause me greater concerns than how efficient it is. [Linked Image]

Stupid should be painful.
Re: Is that ballast Bad? #45505 12/03/04 05:06 PM
Joined: Jun 2003
Posts: 1,143
DougW Offline
Remember - depending on how old that ballast is, it may have PCB's (Poly Chlorinated Biphenyls) in it - they're a carcinogen.

IOW, don't lick yer fingers!

And you might want to double-wrap the old ballast when you throw it out.

Re: Is that ballast Bad? #45506 12/04/04 03:41 AM
Joined: Sep 2003
Posts: 119
ComputerWizKid Offline
I hve a question how old do balast have to be to have PCBS? and I have an old T12 fixture from the 50-60's buzzz that ballast goes but it still works and I like the look of the fixture but if the ballast goes will that old one have pcbs in it?

Theres always enough room in the junction box.You just need a bigger hammer


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