Exploding lightbulbs

[jclogston]

Hey guys, this is my first post and I need some outside help. I have a customer who has a kitchen circuit that has fried three dishwahers and several times, their recessed lights actually have their lightbulbs exploding, shattered glass, the whole works. The other day, both recessed bulbs blew within minutes of each other. I took apart every connection on the circuit starting at the panel and ohmed the wires and it all checked out okay. My next step, I think is to pull out the old circuit and install from scratch everything. I don't think it's a surge problem because this is the only circuit in the whole house affected. Any suggestions would be great. Thanks.

 

[petersonra]

could well be an intermittent open neutral somewhere.

 

[JohnJ0906]

could well be an intermittent open neutral somewhere.

I agree. Is this 1/2 of a Multi-wire branch circuit? What was the voltage? (Use a digital Multi-meter)

Check voltages at the kitchen, panel, everywhere possible, and check other places in the house too.

 

[LarryFine]

Is this 1/2 of a Multi-wire branch circuit?

Sounds plausible. Find the breaker(s) that supply this circuit, trace its ungrounded conductor to the cable it goes to, and see if (1) there is a second ungrounded conductor, and (2) check that cable's neutral-bus connection.

 

[jclogston]

Thanks guys. First, it is not a multi wire branch circuit. The voltage was pretty stable around 118vac. And finally, I opened all connections on the circuit and ohmed it out and it all seemed okay. Unfortunately, it sounds like rewiring from scratch is the best solution. As you guys know, you can only check connections that you can see.
I appreciate the suggestions.
James

 

[peter d]

Unfortunately, it sounds like rewiring from scratch is the best solution. As you guys know, you can only check connections that you can see.

Blown lightbulbs usually don't happen from bad connections on non-shared neutrals. It may be on the utility end, or in the panelboard itself.

 

[brian john]

Rewiring a 2-wire circuit should not be necessary, as stated above the most likely cause of this is an open neutral. Power quality isues other than a total loss of power are not a major concern with 2-wire open conductor (there are other concerns LIKE FIRE) Since it is a 2-wire it almost has to be in the panel or upstream from the panel (towards the utility).

You rewire this and the problem persist and your credability sinks as you try to collect payment.

Did you megger the circuit or use an multi-meter ohm meter?

Did you trace the circuit completly to the panel to verify a 2-wire the complete run of the circuit?

I would still check all connections in the circuit.


Try placing a load (push it like 16-20amps) on the circuit and monitor the voltage. Check all neutral connections look closely at the neutral bus and the conductor termination connector for loose connections.

 

[coulter]

... several times, their recessed lights actually have their lightbulbs exploding, shattered glass, the whole works. The other day, both recessed bulbs blew within minutes of each other.

Tell me about these lightbulbs exploding, shatering glass, Is this a standard A-23 edison base, 120V bulb? What could go wrong with a 120V residential circuit that could make a bulb shatter?

carl

 

[coulter]

Second question:

... I have a customer who has a kitchen circuit that has fried three dishwahers and several times, their recessed lights actually have their lightbulbs exploding, shattered glass, the whole works. ...

... I don't think it's a surge problem because this is the only circuit in the whole house affected. ...

Am I reading this right, the dishwasher and the lights are on the same circuit?

carl

 

[brian john]

That's why I said it is in the panel or upstream from the panel.

 

[iwire]

That's why I said it is in the panel or upstream from the panel.

Even then I have the same question as Carl.

Assume a open neutral and dead short on one leg, then 240 to the lamp.

In my experience 240 volts to a 120 lamp makes it a flash bulb not a glass shattering event.

 

[brian john]

Not saying this is the case BUT I have had some extreme exaggeration from customers experiencing voltage anomalies, unless I see it myself I chalk it up to over telling of an incident, not by the poster but his customer.


I have heard of BUT NOT SEEN incandescent lamps exploding from 277 VAC and do not necessarily believe this.

I can not think of any voltage anomalies that could result in a incandescent lamps exploding. Well maybe 5kv or higher.

As a kid I had expierence with exploding lamps, but it may be because I was spraying them with cold water.

 

[jrannis]

Exploding Lamps

Exploding Lamps

I have seen this happen. Filament Rupture causes lots of pressure inside of the lamp. Could have been a bad batch. Could be unrelated to the dishwasher.
Seems odd that the dishwasher and the lighting circuit are on the same breaker. Sounds like someone cheated somewhere along the way.
My money is on a loose neutral. I would check all of the terminations in the panel, the main and the service. (good practice on all residential service calls).
You should call your utility and report the problem I have found lots of bad splices in service drops that cause strange problems.

 

[andinator]

As a kid I had expierence with exploding lamps, but it may be because I was spraying them with cold water.

That made my Turkey Day. Still giggling. Getting strange looks from family.

 

[coulter]

I have seen this happen. Filament Rupture causes lots of pressure inside of the lamp. ...

I've never seen this - not even heard of it happening. Couple of questions:

What did you attribute the event to? If over voltage, what was it?

What was your evidence that "filament rupture" caused this over pressure?

just curious

carl

 

[coulter]

As long as we are on the subject of light bulbs, I've noticed thare are two types of incandescent halagens on the market. One is thin glass maybe like a normal bulb. The other is significantly heavier glass. Anyone know why the difference?

carl

 

[George Stolz]

In my experience 240 volts to a 120 lamp makes it a flash bulb not a glass shattering event.

I have seen lamps explode when energized to 240V. At a 24-plex, the rough-in crews had a bad habit of mislabelling the baseboard heater's home run, and on occasion would mark the wrong one. The bathroom vanity in one unit exploded as I hurried to the panel to kill the circuit. Of course, in the heat of the moment I didn't think of turning off the switch at the wall.

I think it would take a pretty unique setup to cause lamps to explode under an open neutral situation, but I imagine it could happen. Especially if the failure of one appliance caused the voltage to swing wildly during the failure, I can picture it.

 

[jrannis]

I've never seen this - not even heard of it happening. Couple of questions:

What did you attribute the event to? If over voltage, what was it?

What was your evidence that "filament rupture" caused this over pressure?

just curious

carl

Maybe you have noticed a bad lamp coming back on and being much brighter than it was before it initially failed.
Post failuer the loose parts of the filament supports now have two short sections of the ruptured filament hanging from them. They touch back together and "weld" them selves back together with a bit less filament and less resistance, greater currect flow.

Ive seem this in ceiling fans and other places with vibration.

ALWAYS turn off the power before changing a lamp. Its good practice and looks professional in the presence of your customer.

 

[brian john]

When I ran a service truck there were lamps rated 130 VAC with a rubberized coating..possible tuff skins or Rhino Skin...something like that.

Made life in a NASTY crawl space a bit better...

Murphy's Rule of crawl spaces: the nastier and tighter the crawl space, the more likely you are to drop your drop light and pop the bulb when you reach the furthest point from the entrance.

 

[iwire]

I will concede it must happen as more then a few have said so.

But I still really want to know how.

I have seen this happen. Filament Rupture causes lots of pressure inside of the lamp.

OK, lots of pressure from what?

The bulb is empty, there is no gas to expand when heated.