16-03-2004, 08:23 PM
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Timer for metal halide
(Mike) writes:
outlet, the stated he likes 20 amps ones. However, I recently ran
across some nice, grounded 10 amp, outdoor timers ( Intermatic . On
the side they list capcaity as 1200 amps R Resistive or 1200 amps
Tungsten. I know that Metal halides are different, but do I really
Tungsten lamps are mostly resistive.
A MH light is an inductive load because of the transformer, which is a
hassle. The transformer will give you power surges, which will in turn
provide nice sparks in a mechanical relay or wear and tear on the
oxide layers in a solid-state relay. In time, things will die,
hopefully not in a spectacular way.
The more expensive the timer is, the better the insides will be
protected from these kinds of surges. A higher power rating means more
robust parts, which will take more abuse before the part dies.
I use a mechanical 2500W digital timer. It is mounted on a tile wall
so it can go bang as loud as it wants without burning the house
down. It has lasted 18 months or so now, and it cost me about $20. I
am on 240V, so the parts only need to cope with half the current that
a 2500W part would need to handle in your part of the world. It
controls about 500W of miscellaneous lights.
YMMV.
Geir
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