T
Travis Evans
- Jan 1, 1970
- 0
I'd like to think that I'm reasonably cautious and safety-conscious
around this stuff, but despite my best efforts it sometimes just seems
to hate me. Today I turned on my 70-watt M98 metal halide fixture
(after having used it several times within the last few days without
incident) and was greeted with a really loud POP, like a firecracker.
The lamp still appeared to start up, but I quickly shut it off because
it scared me.
First I visually inspected the lamp, whose arc tube seemed to possibly
be significantly more blackened now than a few days ago, though I can't
be positive since this is relying on eye and my (not too terribly
reliable) memory. The lamp in question isn't too terribly old, though
its starts-to-burning-hours ratio may be fairly high.
Electrically, something was definitely not right. Without a lamp in
place and with power applied, my meter showed power consumption of
around 70-100W, possibly intermittently. I was also seeing continuity
between neutral and ground at the plug, which didn't look right given
that the ground and neutral feed wires inside the fixture are not
connected together at any point.
As I disassembled the fixture, I really should have checked for any
obvious signs of loose/dangling wire ends, etc., that would have
explained what had happened, but I didn't think of it. Instead I just
took everything apart, checked continuity of individual components for
anything odd (didn't find anything), and then disconnected and
reconnected all of the wiring from scratch, again checking that the
connections were all tight (all of which I had thought I had done the
last time I was inside).
After reassembly, everything seems normal again for now--no path between
neutral/ground and power consumption without a lamp of only a few watts.
Finally, I carefully powered up for a couple of seconds with the MH lamp
back in place. It appeared to start normally.
I suspect that something in the circuit had somehow gotten shorted
(maybe a neutral somehow came in contact with the grounded chassis?).
It's just not totally clear whether this was from a wire falling out of
a wirenut or what have you. My main concern now is with how safe
resuming operation would be--i.e., is there any increased chance of
components like the ballast, ignitor, and especially the lamp, failing
catastrophically later after this event. The lamp is unprotected, and
while the fixture is enclosed and designed for this type of lamp, I
don't really need any more "excitement" for a good long while.
So I thought I'd ask for advice before doing anything else.
around this stuff, but despite my best efforts it sometimes just seems
to hate me. Today I turned on my 70-watt M98 metal halide fixture
(after having used it several times within the last few days without
incident) and was greeted with a really loud POP, like a firecracker.
The lamp still appeared to start up, but I quickly shut it off because
it scared me.
First I visually inspected the lamp, whose arc tube seemed to possibly
be significantly more blackened now than a few days ago, though I can't
be positive since this is relying on eye and my (not too terribly
reliable) memory. The lamp in question isn't too terribly old, though
its starts-to-burning-hours ratio may be fairly high.
Electrically, something was definitely not right. Without a lamp in
place and with power applied, my meter showed power consumption of
around 70-100W, possibly intermittently. I was also seeing continuity
between neutral and ground at the plug, which didn't look right given
that the ground and neutral feed wires inside the fixture are not
connected together at any point.
As I disassembled the fixture, I really should have checked for any
obvious signs of loose/dangling wire ends, etc., that would have
explained what had happened, but I didn't think of it. Instead I just
took everything apart, checked continuity of individual components for
anything odd (didn't find anything), and then disconnected and
reconnected all of the wiring from scratch, again checking that the
connections were all tight (all of which I had thought I had done the
last time I was inside).
After reassembly, everything seems normal again for now--no path between
neutral/ground and power consumption without a lamp of only a few watts.
Finally, I carefully powered up for a couple of seconds with the MH lamp
back in place. It appeared to start normally.
I suspect that something in the circuit had somehow gotten shorted
(maybe a neutral somehow came in contact with the grounded chassis?).
It's just not totally clear whether this was from a wire falling out of
a wirenut or what have you. My main concern now is with how safe
resuming operation would be--i.e., is there any increased chance of
components like the ballast, ignitor, and especially the lamp, failing
catastrophically later after this event. The lamp is unprotected, and
while the fixture is enclosed and designed for this type of lamp, I
don't really need any more "excitement" for a good long while.
So I thought I'd ask for advice before doing anything else.