Exploding incandescent lamps

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sfav8r

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I just did a service call for a client who says that the lamps she is putting in her recessed lights are exdploding.

The first time she assumed it was a freak accident, but she replaced the lamp and two days later it did the same thing. There were literally pieces of glass in the hallway.

I cannot think of a miswiring that could cause this. I originally thought it could be a "california 3-way" wher somehow one of the feed got moved to another phase, resulting in 220v at the bulb, even 220 shouldn't blow the bulb apart.

I checked the wiring, fixture, installation, and the general envirponment and everything is much better than average.

I can think of only three things that could cause this:
1) Faulty lamps..I suppose there could have been a series of bad lamps if they were the same lot #.
2) Water (or some other liquid) contacted the lamp while it was hot.
3) Excessive heat.

The location of the fixture pretty much eliminates the possability of water, it is in a hallway well away from any source of water and there is no plumbing in the vacinity that could have leaked. The fixture is a lightolier. It is mounted in a dropped ceiling with 12" of clearance. On top of the fixture is a concrete slab separating if from the floor above.

The only thing that is somewhat different is that they are using A lamps, which we generally don't put in recessed cans, but they are 60w and the fixtures specifies a 60 A lamps as suitable. Also, the exact fixure is throughout the house and is using the same lamos with no issues.

Finally, just to convince myself, I left a data logger hooked up for a few days and the power quality is good. There is also another fixture on the same circuit about 4 feet away and it has not experienced any problems.

Any thoughts?
 
MWBC with a loose neutral. It may be occurring when the other side of the circuit it connected to its load, maybe another light some where else in the house. I would start tracing out the circuit, and at the panel find the neutral for the circuit and see if it is a MWBC.
 
acrwc10 said:
MWBC with a loose neutral. It may be occurring when the other side of the circuit it connected to its load, maybe another light some where else in the house. I would start tracing out the circuit, and at the panel find the neutral for the circuit and see if it is a MWBC.

I did check that out and it is a MWBC, however, I see no indication of any loose connections anywhere in the circuit and the other lamp controlled by the same switch is fine. Do you think that 220v would "explode" the lamp? I have seen them get real bright and burn out, but never actually break.

Thanks
 
Ive never "seen" it happen but I have heard of it happening. I would look for bad splicing or if they used those Ideal taps ( yellow or brown ) they are notorious for being intermittent and they were popular in the 70's.
 
IMO, you either have a bad lot of bulbs or you are using bulbs that actually are getting scored by the ceramic socket. I have seen this happen. The socket was deep and the glass when screwed in would actually get scored around the base of the bulb. In a few days the bulb would just drop out.
 
Dennis Alwon said:
IMO, you either have a bad lot of bulbs or you are using bulbs that actually are getting scored by the ceramic socket. I have seen this happen. The socket was deep and the glass when screwed in would actually get scored around the base of the bulb. In a few days the bulb would just drop out.

I think dennis has the most logical answer so far. I've done calls where the building lost the neutral at the service entirely and it didn't make bulbs explode. Something's wrong w/ the glass.
 
I've seen a loose or open neutral cause incadescent bulbs to explode.

It's first thing that I look for if I see (more like hear of) exploding light bulbs.

Just my opinion
steve
 
hillbilly said:
I've seen a loose or open neutral cause incadescent bulbs to explode.
I have, too. Recently, in fact, we did a service call where we found a couple of exploded bulbs and a burned wall-wart. The problem was a bad neutral connection at the pad-mounted transformer.

The unbelievable part was that the POCO turned off the main breakers (two 150a panels), then measured the voltages and said everything was fine. I turned one back on and measured them myself.

The POCO finally came back and saw their error, found the problem, fixed it, and told me that this never would have happened if the house had two ground rods like "it was supposed to have." :roll:
 
LarryFine said:
The POCO finally came back and saw their error, found the problem, fixed it, and told me that this never would have happened if the house had two ground rods like "it was supposed to have." :roll:

Does the POCO in your area require ground rods driven all the way to the transformer neutral??

-Jon
 
The only time we had this issue,- was with halogen lamps in track heads,we too checked all the scenerios the OP had,we ended up changing all the lamps out to standard a-lamps and all has been good...
 
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