Ballast after Ballast - Electrician Talk - Professional Electrical Contractors Forum

shazam · 02-22-2008, 08:07 AM

I'm asking this question for another electrical contractor, who called me and got gears turning in my mind.

He has been called out to an apartment complex to repair a 4-tube 120v fluorescent sign.
A quick glance revealed a bad ballast. It was charred.

After cleaning up and replacing the apparent bad one with a new one. He covered the photocell and all was fine.

Two days later, a call-back.

Second ballast fried.

Megged the line. Its Good.
Proper line voltage (113vac phase to neutral)
No recent digging in the area.
No other known problems from any of the other branch circuits that share that subpanel.
Tombtones are clean.
He put in new bulbs and another new ballast from a different manufacturer
and it also fried in about a week.

He is stumped and he gave me a call and I am also stumped.

Anybody here ever get this problem before?
What are we overlooking?

a-bulb · 02-22-2008, 08:20 AM

Are the load wires from the ballast to the socket shorted out to the housing? Or may be a loose wire at a socket, sometimes those push ins come loose? good luck.

shazam · 02-22-2008, 08:35 AM

Quote:

Originally Posted by a-bulb

Are the load wires from the ballast to the socket shorted out to the housing? Or may be a loose wire at a socket, sometimes those push ins come loose? good luck.

He said the tombstones were clean and not touching metal.
I don't know if he has checked the fixture wires.
I will pass this information on to him as a reminder. Thanks

480sparky · 02-22-2008, 08:56 AM

Are they the original ballasts in the fixtures? If so, they may be super-cheap imports.

shazam · 02-22-2008, 09:04 AM

Quote:

Originally Posted by 480sparky

Are they the original ballasts in the fixtures? If so, they may be super-cheap imports.

He and I discussed that. I was telling him about the cheap ballast thread.
This is why he chose a different manuf.
Actually, he used Advanced and then tried Sylvania.

Wireless · 02-22-2008, 09:32 AM

Is it a HO ballast?

waco · 02-22-2008, 11:34 AM

I'd check for voltage from the light ground to neutral and there is an outside chance the ballast is seeing a high direct current component. If that phase is feeding a lot of inductive loads, the power factor could be way off which would lead to heat buildup in the ballast -- like a motor that can't get up to speed.

brian john · 02-22-2008, 02:21 PM

Is this part of a multi-wire branch circuit?

shazam · 02-22-2008, 06:02 PM

Quote:

Originally Posted by Wireless

Is it a HO ballast?

No......

shazam · 02-22-2008, 06:03 PM

Quote:

Originally Posted by brian john

Is this part of a multi-wire branch circuit?

I have to ask.

shazam · 02-22-2008, 06:04 PM

Quote:

Originally Posted by waco

I'd check for voltage from the light ground to neutral and there is an outside chance the ballast is seeing a high direct current component. If that phase is feeding a lot of inductive loads, the power factor could be way off which would lead to heat buildup in the ballast -- like a motor that can't get up to speed.

This is along the lines of what I was starting to think as I drove to work earlier.

I think there is something else sharing this neutral.

InPhase277 · 02-22-2008, 06:26 PM

Quote:

Originally Posted by shazam

This is along the lines of what I was starting to think as I drove to work earlier.

I think there is something else sharing this neutral.

Why is the voltage with no load so low? 113 V. With no load there is no voltage drop, it should be higher. There may be a coincident load sharing the neutral somewhere in the building that only comes on at certain times. It may be fine when checking it, then later, bang, 208 on it.

Hey there's a thought. Try using a multivolt ballast, instead of just a 120 V.

InPhase277

shazam · 02-22-2008, 06:46 PM

Quote:

Originally Posted by InPhase277

Why is the voltage with no load so low? 113 V. With no load there is no voltage drop, it should be higher. There may be a coincident load sharing the neutral somewhere in the building that only comes on at certain times. It may be fine when checking it, then later, bang, 208 on it.

Hey there's a thought. Try using a multivolt ballast, instead of just a 120 V.

InPhase277

I haven't been to the job site, I would assume the voltage drop has something to do with the fact that it is probably a good distance from the service.

It leaves the service entrance equipment, goes to a subpanel, then out to a sign.

a-bulb · 02-22-2008, 08:19 PM

screw it just run a new feed, tell the customer you have no choice. Get the back hoe ready here comes Shazam, thank you maam.

InPhase277 · 02-22-2008, 10:38 PM

Quote:

Originally Posted by shazam

I haven't been to the job site, I would assume the voltage drop has something to do with the fact that it is probably a good distance from the service.

It leaves the service entrance equipment, goes to a subpanel, then out to a sign.

That's my point. Without a load, that is, without the ballast connected, you will have no voltage drop, no matter how long the run is. 113 V seems awful low, there may be a tap bad.

InPhase277

shazam · 02-23-2008, 08:16 AM

Quote:

Originally Posted by a-bulb

screw it just run a new feed, tell the customer you have no choice. Get the back hoe ready here comes Shazam, thank you maam.

No, no not me this is my buddy's mess.

He can sort it out.

shazam · 02-23-2008, 08:17 AM

Quote:

Originally Posted by InPhase277

That's my point. Without a load, that is, without the ballast connected, you will have no voltage drop, no matter how long the run is. 113 V seems awful low, there may be a tap bad.

InPhase277

Okay, now I got ask if he read that with or w/o load.

brian john · 02-23-2008, 08:29 AM

Quote:

screw it just run a new feed

That is the shotgun approach to ridding your house of mice. I always want to know why? I would do this for free just to know the answer. Not saying you should spend more money than what a new circuit would cost, but inquiring minds should want to KNOW! If you resolve this issue it may give you insight into other anomalies in the future.

Check for neutral issues, if this is a multi-wire circuit it could result in over voltage.

If it is a 2 wire with GND circuit and there is neutral ground issues the VD could be excessive resulting in under voltage.

Are all the ballast from the same lot, never rule out poor manufacturing. In a pinch LIE and tell them their bad ballast (YOU KNOW LOL).

This is electricity not magic there is always a reason, you just need to rule what is not the reason.

shazam · 02-23-2008, 08:38 AM

Quote:

Originally Posted by brian john

but inquiring minds should want to KNOW!

Precisely! He gives me a call and now I am all ready to run up there on my own time, cause I am curious.

It keeps looking like a neutral issue just from phone calls.

I am not doing much this weekend, I'll prolly go up w/ him at some point just to put this thing to rest.

shazam · 02-23-2008, 10:47 AM

Just talk to him and apparently the "tombstones" WEREN"T CLEAN.

He now says he found one broken and thinks it was resting on the metal frame and he now says it was a HO ballast and fixture.

He thinks he may have solved the problem. We'll see.

Thanks for all your input. I still think there are underlying issues and in less than a year there will be component failure.

I never got to investigate for myself and he seems to think this is the cure. :confused: