Now I know why they call them trouble lights.
This dont make sense. I plugged in one of my trouble lights, and
immediately the bulb made a bright flash and burned out. I did not
think much of it, I figured it was just a common dying bulb. I
unplugged the cord and installed a brand new bulb. I plugged in the
cord and immediately that bulb flashed and burned out. After cussing
about the quality of light bulbs, I got yet another new bulb, and the
same thing happened. Immediate burnout.
At this point, I unplugged the cord and measured the voltage at the
outlet I was using. It measured 117V (normal). I plugged another
trouble light in that same outlet and it worked fine. Then I plugged
in several other power tools and stuff. All worked fine.
That's when I tossed this bad trouble light in the garbage.
However, I do not understand this. It's not getting 220V, so how/why
did the bulbs keep burning out? (just on that cord).
The cord won't cause that to happen. I would check the voltage rating of the
three bulbs that flashed. If it's not problem bulbs, I'd put a meter on the
circuit and watch it for a while, as there could be an intermittent open
neutral, causing high voltage
The cord can't have the neutral side go open? Like right where the
handle meets the cord? And where it stuck itself back together when
the light was taken down from the workplace to the bench to be tested?
If it tested fine on the bench I'd sacrifice another bulb on a fresh
circuit. If the bulb works I'd put the light/cord through a lot of
gyrations before I suspected the old circuit.
Can you explain why you believe an open neutral in the cord will burn
out a bulb?
I think you may have read posts about open neutrals in a main power feed
and unbalanced loads causing high voltage on one phase and low voltage
on the other.
Methinks you need to study that subject a bit more until you understand it.
So, how will a "short" cause the BULB to immediately burn out?
I'd expect a short would more likely pop the breaker for that circuit,
or if it wasn't a "hard short" it might cause localized heating probably
accompanied by a bit of smoke/smell. And, as mentioned elsewhere on this
thread, a poor contact or partial short might heat the bulb base enough
to cause a "mechanical" bulb failure, but not "instantaneously".
I really can't think of anything which could go wrong with a trouble
lamp cord which would cause an "immediate" failure of a bulb as soon as
it's turned on.
I'd go with bad bulbs as the likely cause.
To check that, he OP might try taking a bulb from one of the other
"working" trouble lights he mentioned he had and trying it in that
Or one of the supposed "bad" bulbs and put it in the working trouble light.
My thought would be a high current across the base is blasting them, but
it's hypothetical. A poor vacuum seal on a batch would provide the
symptom as well, certainly.
I'd do continuity checks on the cord, socket, etc., first as well as the
Obviously if have another in the batch of bulbs that failed, try it in
another lamp/light first before the test of the problem one.
The only idea on the bulbs themselves I have would be a batch w/ an
imperfect vacuum seal unless they are a really cheap Chinese import
I have a trouble light that is used for automotive use ,with 12 volt
bulbs just like 110 bulbs.Wife got my spare bulbs and blew six of them
before she noticed they were the 12 volt ones. Now I keep my shop locked
A little bit OT, but I wonder how many folks here know that they still
make and sell standard looking light bulbs with left hand threads?
It's an anti-pilferage thing. They were used aplenty on subway cars back
when incandescent bulbs were the only practical lights abvailable.
I think the reason they are still being made is that the strings of
lights used around construction sites are easy targets for "bulb
snatchers" and using bulbs with left hand threads discourages that.
Jeff (Who wonders if anyone ever sold "thread reversing" light bulb
socket adaptors? <G>)
Back in the early 70's I worked for an electrical
supplier and we sold a lot of left handed bulbs and
pig tail sockets to construction companies. The thought
of some miscreant trying to steal the bulb is kind of
The solder is just an electrical connection. The gas seal is made by
sealing a glass tube used to remove air from the bulb.
This isn't to say that a poor connection might not generate enough heat
to soften glass and lose the seal - but it would have to melt glass, not
FWIW, bulbs made for ceiling fans will stand up to the rough service a
drop light usually sees almost as well as the rough service bulbs made
for drop lights, at a fraction of the price. I finally started using
CFL's and find they last longer than rough service bulbs and don't put
out the heat. We have had people at work burn carpets by setting drop
ights down and forgetting about them, beside burning the crap out of
arms, but the main thing is that one drop of sweat on a hot incand. will
pop it immediately. One afternoon, me and a co-worker popped 4 or 5 in
about a 20 minute period that way. Larry
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