Don Klipstein wrote:
In article .com,
Father Haskell wrote:
How much current is drained by a 2x 40 watt T12 magnetic ballasted
shop light trough at peak current draw? I assume this is at startup,
while trying to saturate the transformer and ignite the tubes. How
much
is drawn once the lights are running?

Short version: How many such fixtures (too cheap to replace
the old ones) can be run on a 15 amp circuit?

The USA-usual "traditional" high power factor 2xF40T12 rapid start
ballast that is about 8.25 inches long, 9.5 inches long including the
mounting flanges, 2.25 inches wide, 1.5 inches thick, rated "Class P"
(having a thermal cutout), and noted as having "high power factor"
typically draws .8 amp when the lamps are running and less when the lamps
are starting.

I would not push the limit of the circuit. Somehow I would rather not
put more than 12 of these on a circuit, and first actually read a ballast
label for the current draw.

http://www.codebookcity.com/codearti...article210.htm - with a
few notes from the National Electrical Code - states that a continuous
load shall not exceed 80% of the rating of the circuit.

If the ballast has a shorted internal series capacitor, then it will
draw much more - I would hazard to guess 1.5 to 2 amps. The "Class P"
thermal cutout switch will not always cycle on and off when that happens,
but lamp life is usually noticeably reduced and the lamps may not look
much brighter. However, I consider it a safe bet that probably none to
at worst few of your fixtures will have that problem, and never will most
have it before you notice and replace the ballasts.

The shorter length ballasts used in cheap shop lights can do anything,
but usualy draw similar current (near or somewhat under an amp), usually
result in less light output, sometimes maybe often result in shorter lamp
life, and often require the fixture to be suspended in mid-air (such
fixtures usually come with chains) so that the ballasts do not overheat.
Those ballasts are sometimes called "residential grade", and my
impression is that a better name for such grade is "stool specimen".

- Don Klipstein )

Humbug. I have a bunch of these "cheap lights"
three currently operate in my garage/workshop, the
others have been used for Grolux operation. Never
had a problem with any of them. And yes, the
fixtures including bulbs cost less than a
replacement ballast from an electric shop.