On Mon, 3 Aug 2009 06:48:05 -0700 (PDT), stryped
wrote:

At work we have several 480 volt lights HID we are giving away. SOme
of these can be converted to 110 volts with a new transformer and low
bay dome. WOuld these be good for my garage/shop? The maintenance guy
thought they were very bright but put off alot of heat.


There is a bit of Good news - If you have an application with a 14'
to 16' plus ceiling, these lights most likely have Multi-Tap ballasts
inside. Open it and you'll find wires marked for 120 - 208- 240 -
277V.

Skip them anyway, or get them and horse trade for what you really
need. Even if they are free they are still wrong for your application
in several critical ways.

The heat isn't as much of an issue as the lens and mounting
situation is - a 10' ceiling isn't going to cut it even with Low Bay
totally enclosed luminaires.

If you mount either Low Bay or High Bay lights over the bottom chord
of the truss you will have overlapping shadows everywhere driving you
bananas. You'll have shadow lines running across what you are working
on giving you optical anomalies.

If this is a workshop running Metal Halide fixtures you HAVE TO have
the fully enclosed fixtures with bottom lenses. (Not just wire
guards.) Too many flying bits in a shop that can shatter the outer
envelope, and it isn't fun geting shattered hot glass falling on you.

And for Metal Halide with open fixtures overhead (like in a warehouse
where flying debris isn't a problem) you still have to run the
shatter-guard lamps with the extra shield tube inside the envelope,
too - when the inner arc tube ruptures at end-of-life they often break
the outer envelope at the same time - and another hot sharp glass
shower can happen.

For a10' ceiling home shop or small shop, you want good old
fashioned linear fluorescent fiixtures. Either T-5 or T-8 open strips
or "Shop Light" reflectors. Or T-8 polycarb lensed Wraps.

They should have premium high frequency electronic ballasts (20 KHz)
so you do not get 60-Hz Strobing effects, and you want to use tube
guards over the lamps on open fixtures.

-- Bruce --