One of the disadvantages of not having the email address of the author is
that you can't do the following without disturbing everyone...
Excellent posting. Lots of nice information. Well done.
Tim Vitale
[log in to unmask]
510-594-8277
Oakland, CA
-----Original Message-----
From: Museum discussion list [mailto:[log in to unmask]]On
Behalf Of Mike Csontos
Sent: Thursday, March 01, 2012 11:44 AM
To: [log in to unmask]
Subject: Re: [MUSEUM-L] Exploding Lightbulbs - cause and prevention?
I've had three explosions of small non-halogen incandescent lamps at home
and one at the museum where I volunteer. These are 60 watt candelabra bulbs
used in chandeliers of the type GE 60CAC CD4 (though I don't know if they
were all GE).
My theory is that when they burn out, the break in the filament strikes an
arc, vaporizing the filament, producing enough gas to cause the bulb to
explode because of the small space in the miniature lamp for it to expand
and cool.
One factor would be high line voltage, increasing the chance of an arc on
burnout; also the short life. My home line voltage had been running about
10% above normal and sometimes high enough for me to call the power company
to have it reduced. They said it was a faulty regulator. It has been
replaced, and
no explosions since.
Another factor might be high inductance in the line. This would help
sustain an arc. My house is fed through two transformers (overhead hi line
to underground feed to line voltage). I don't know about the museum's line
voltage but the power feed is similar to mine. The museum also has had
several failures of electronic fluorescent lamp ballasts.
If you continue to have problems I would have an electrician or a power
company representative check line voltage, line impedance, and power factor
at the circuit you are using.
Or use another type of lamp.
Mike Csontos
AWA Museum
Bloomfield NY
In a message dated 2/29/2012 8:55:36 P.M. Eastern Standard Time,
[log in to unmask] writes:
Thanks everyone who has weighed in so far. Our maintenance/facilities
guys will be checking into things more in the morning before we open. So far
their best guess is some sort of power surge.
To answer some questions:
a.. No, we've not been in the habit of wearing gloves to change bulbs.
We'll definitely start! (Am I the only one who'd never heard of this?)
b.. The fixtures are rated up to something like 100 watts. We're
significantly under.
c.. The bulbs we've been using are GE Halogen Edison Flood, 60 watts.
PAR 30. (Here's the exact bulb, if this helps:
http://www.amazon.com/85116-Indoor-Floodlight-Halogen-60-Watt/dp/B00291WZTW/
ref=sr_1_5?s=hi&ie=UTF8&qid=1330554039&sr=1-5)
d.. In general, these bulbs have not been lasting the 3,000 hours
promised on the packaging. Based on the number of bulbs we've purchased in
the past year, I'd say they're lasting, on average, less than half that
long, although whether we're replacing bulbs from 10 fixtures monthly or 100
yearly is unclear. We've recently started tracking when we replace the bulb
in any given fixture so we can (hopefully!) eventually figure out whether
the problem is with our hardware, or with the bulbs themselves.
e.. We're located in northern Utah - definitely no lightning strikes
we could attribute anything to recently. Today's weather is wet and windy. I
don't recall the weather the day the other exploded.
f.. Vibration is a possible concern. We share a building with the
Senior Center (we're City funded), and they are upstairs. While things are
generally pretty tame, they do sometimes have clogging and/or square dancing
classes up there which rattle the whole building quite a bit. Bulbs
exploding do not seem to correlate to building vibrations, however.
g.. We have not switched brands recently.
h.. There's not a dimmer on any of these.
i.. No recent construction or additions to the building's electrical
system.
Thanks again for all the helpful suggestions. Please keep them coming if
you think of anything else.
Thanks,
Kaia
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