Light bulbs exploding in wall light fixture.

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  #1  
Old 01-18-05, 03:22 PM
mmmmiiiicccc
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Light bulbs exploding in wall light fixture.

I live in an apartment in a very old 3 story stone building built in the late 1800ís. I have an electrical background and have always done most of my own electrical repairs and upgrades but this is differentÖit is not my building. I donít want the responsibility. My question is what is the most likely cause of bulbs exploding?

I realize thatís asking a lot but take into consideration a leaky roof, multiconductor copper cloth and varnish insulated wiring and a frugal landlord. The wall mounted light fixture in question first started to be intermittent and then proceeded to blow light bulbs one after the other. Every time the wall switch was turned onÖbang.. Another bulb gone. Now it doesnít work at all. The fuse did not trip nor is there any sign of electrical problems in the room or in the rest of the apartment. Since my own apartment is basically wired on one 25-amp fuse itís most likely wired similarly in the apartment in question.

About 10 feet away at the window at the top of the dormer is a new water leak. This in itself is not surprising since the eaves have never been cleaned and are probably all rotted out causing water to flow where it shouldnít. There are no immediate signs of water in the wall with the light fixture (it is perpendicular to the window) but I know for a fact the roof is full of leaks with bad eaves troughs leading right to them.

Iíd love to hear your horror stories and some advice. Iíve already sent a letter to the landlord asking him to call an electrician immediately to have a look and do some troubleshooting. So what do you think I should expect?

Thanks for your time.
 
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  #2  
Old 01-18-05, 03:27 PM
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Try measuring the voltage. Got a voltmeter?
 
  #3  
Old 01-18-05, 05:08 PM
mmmmiiiicccc
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Originally Posted by John Nelson
Try measuring the voltage. Got a voltmeter?
Hehe...I have a toolbox full of them but how to get at the wiring? I tried hanging a ceiling light in my own apartment only to find cloth instulation falling off the wire just from pulling it down from the non-existent box. To tell you the truth I'm too scared to touch it. Not because I'm afraid of electricity that's what breakers are for. I'm just scared of opening up a can of beans that I don't want to be resposible for. I know when I pull that fixture away from the wall I'm going to find that same dam cloth wiring falling onto the floor.

Ever leave a tub of sour cream in the fridge and re-discover it 1 or 2 months later? You know there's a better than average chance it's full of mold but there's also a chance it's perfectly ok? You stare at your baked potato salivating thinking...do I really want to lose my apetite? :-P
 
  #4  
Old 01-18-05, 05:45 PM
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Just measure the voltage at the bulb socket. Unscrew the bulb. Then carefullly, very carefully, put one probe on the button at the bottom of the socket and one probe on the shell of the socket.

Don't count on that breaker saving your life. The breaker trips at 15 amps. You die at 0.01 amps.
 
  #5  
Old 01-18-05, 06:31 PM
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I am concerned about your comment about the fuse size. Do you really mean a 25 amp fuse? I hope not. The circuit you have is probably rated for a 15 amp fuse. I hope you mistyped, and meant to type 15.

If the fuse is in fact 25 amps, then call the codes enforcement officer for the town or city you live in. You have a serious problem that needs to be addressed NOW.
 
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Old 01-19-05, 05:46 AM
mmmmiiiicccc
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Originally Posted by racraft
I am concerned about your comment about the fuse size. Do you really mean a 25 amp fuse? I hope not. The circuit you have is probably rated for a 15 amp fuse. I hope you mistyped, and meant to type 15.

If the fuse is in fact 25 amps, then call the codes enforcement officer for the town or city you live in. You have a serious problem that needs to be addressed NOW.
Hey I know EXACTLY what you mean but these are breakers and ratting on a man I consider a neighbor giving me cheap rent isn't an option. There is a stack of safety violations in this place but I keep my trap shut about it and only mention it if Iím about to fix it. I keep my power needs down well below 15 amps and use my stove outlet for anything 5 amps or over.

Now if he sits on his hands I'll go up with a meter tonight but chances are if an electrician comes today he'll do the exact same thing. I just wanted to have some idea of what to expect. I've never had bulbs exploding in any light I've ever worked on.
 
  #7  
Old 01-19-05, 05:49 AM
mmmmiiiicccc
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Originally Posted by John Nelson
Don't count on that breaker saving your life. The breaker trips at 15 amps. You die at 0.01 amps.
As far as I'm concerned a breaker is for shutting off BEFORE I work on something NOT after my heart stops *lol*
 
  #8  
Old 01-19-05, 06:02 AM
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The only way I can think of that would cause a bulb to "explode" would be excessive voltage. In your situation, there are probably two ways that could happen. The most common (and likely) is an open neutral. The other way is not very likely but could happen if your building has four wire three phase delta service. In this situation, you have two legs that are 120 volts to ground and one leg that is 208 volts to ground (on a nominal 120/240 volt service). If some moron used that leg (call the "freak leg" in these parts, but also referred to as the "high" leg) to provide general lighting circuits, you could experience an unacceptably high voltage for lights and receptacles that are supposed to be 120 volts. An open neutral situation would normally be intermittent and be dependent on something (necessarily a load much larger than the 60-100 watt bulb that is exploding) being on the other leg of the service at the time.
 
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Old 01-19-05, 08:15 AM
mmmmiiiicccc
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Originally Posted by txdiyguy
The only way I can think of that would cause a bulb to "explode" would be excessive voltage. In your situation, there are probably two ways that could happen. The most common (and likely) is an open neutral. The other way is not very likely but could happen if your building has four wire three phase delta service. In this situation, you have two legs that are 120 volts to ground and one leg that is 208 volts to ground (on a nominal 120/240 volt service). If some moron used that leg (call the "freak leg" in these parts, but also referred to as the "high" leg) to provide general lighting circuits, you could experience an unacceptably high voltage for lights and receptacles that are supposed to be 120 volts. An open neutral situation would normally be intermittent and be dependent on something (necessarily a load much larger than the 60-100 watt bulb that is exploding) being on the other leg of the service at the time.
Thank you sir this is the kind of stuff I wanted to hear. It's a place to start. I know all my circuits check out as grounded and measure at 120V. I'm on the ground floor and there are open rafters under my floor. Itís an electricians dream. I wouldn't be surprised if some "short cuts" were made in order to get the third floor rented without first busting up the place. This is the first time anything like this has happened up there and there aren't any new appliances or changes to the apartment. My guess would be if there was an existing problem it's unlikely to have waited until now to rear its ugly head.

Basically what I've found at the breaker panel is 2 monster blacks and 1 white coming in off the street that splits off into two 100 amp meters and one 200 amp meter. The two 100 amp meters each connect to a separate 60 Amp shutoff and then branch out into 1 apartment each. The 200-amp line hits a 200-amp shutoff and then hits the 200-amp meter then a large breaker panel with 24 breakers. I see numerous boxes here and there after that for water heaters, furnace and separate fuse panels with 30 and 60 amp shutoffs in the basement and in the other apartments. Itís fairly neatly done with nothing standing out that sparks my attention. Does this help identify the service?

Weíll see what happens..electrician arrives within the hour and Iíll be on his heals the whole time.
 
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