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19-03-2004, 02:12 PM

(Mike) writes in article dated 14 Mar 2004 11:43:40 -0800:
Can anyone provide guidance on how large a timer I need for a 400W
metal halide grow lamp? The vendor suggested a 15 amp grounded
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
need a 15 amp timer or will these 10 amp ones work?

(I think you mean 1200 Watts, not amps.)

The "right" answer to your question should be stamped on the fixture
somewhere, or on the ballast if the components were manufactured separately.

Metal halides are not a purely resistive load because of the inductors in
the ballast, but even if you double the 3.3A current required to sustain
400W it's less than 10A.

-- spud_demon -at- thundermaker.net
The above may not (yet) represent the opinions of my employer.