[SML] LED lights in the Scene Shop

[Duncan Mahoney]

I have been keeping an eye on LED lighting for a while, and I'm not sure LED
technology is really ready for use as work light in areas where you need
reasonable color rendering and are on a budget.  There are bright fixtures
available, some with decent CRI ratings, but the prices do not compare
favorable with existing (almost equally efficient) "energy saving" lighting
technologies like T5/T8 fluorescent or Ceramic Metal Halide.
  
See if you can get the PTB to consider something besides LEDs.  T5 and T8
fluorescent tubes with a CRI of 85 are readily available and about $3 per
tube or less, T8 lamps with a CRI of 98 are available, but are about 3X the
price.  Our paint area is lit with 4000K Ceramic Metal Halide lamps with a
CRI of 92.  The law limits buildings to so many watts per square foot for
lighting and that was the best CRI we could get with the efficiency required
when the building was built.  The fixtures do require a bit of ongoing
maintenance so I'm always looking for a better option that is brighter
and/or more efficient with at least the same CRI, and not hopelessly
expensive.  I have not found it yet. The metal and wood working areas of the
Shop are lit with T8 fluorescent fixtures.

One thing to remember and impress upon the PTB, just because the lamps might
last practically forever does not mean they should be left in service until
they fail.  For maximum efficiency the lamps should be replaced every 3
years or so.  Last year I noticed that the Shop seemed a bit dark.  The
lamps had mostly been in service 5+ years and many of the Ceramic Metal
Halide had been replaced at various times with different brands by the
maintenance staff, so there was a variety of color temperatures.  We
re-lamped the CMH lamps and saw an immediate 20% boost in the light levels
in that area and when the T8 fixtures were re-lamped there was a 25% boost
in the light levels measured on the workbench surfaces.  

And here's a dirty little secret about LEDs ...their output will also
degrade over time, pretty quickly too if the heat management of the fixture
is poorly designed

Invest in a light meter if you don't have one, try to specify an adequate
light level at the workbenches.  Document the light levels of the newly
installed system and test yearly to monitor any degradation.

Our Shop averages about 300 lux at bench height, which is bright for a
warehouse, but a bit dim for a workshop according to most sources I've read.
As a result we have task lighting at a lot of the tools.  

Duncan Mahoney
Director of Technical Direction
Associate Professor of Theatre Practice
University of Southern California School of Dramatic Arts