Re: MH bulb has inner and outer glass bulb
"When I talked to the guy who made up my last MH setup, I told him
about the potential hazards of exploding MH bulbs and UV radiation
released. He said: they don't explode when they burn out and he's
seen tons of burnt out ones. He also remarked that the safety
glass on the lamp fixture is not usually present since the bulbs
are actually two bulbs, a small one about 1.5" and the larger
enclosure. Presumably the large bulb contains fragments in
case the little guy bursts. Any comments?"
The Venture Lighting manual explains that non-passive failure of
these bulbs is rare, but that it does occur usually when the bulb
is burnt in the non-vertical position or in a postion that does
not meet with the manufacturer's specifications. If the bulb
explodes, I think that the UV radiation would be less of an
immediate worry than the hot flying glass and metal particles.
This is the reason for the acrylic lens in the fixture.