I had to replace the burned out FL long straight tube in my shop light,
and noticed the marking indicated "40 watt".
I was thinking - our twist CFLs that replaced the our 60 watt bulbs
are only running about 14 real watts.
SO - are the traditional long straight tube FL shop lights actually using 40
or is that just and equiv and the real watt usage is much less, just like
the CFL ?
If not - then that means the long tube FL are as in-efficient as a normal
They use 40W, they will be producing the light equivalent to ~150W of
incandescent lamps. Unfortunately, few people these days seem able to
understand what efficiency really means, or calculate the MPG their car
Just a little gee whiz info
I put a clamp on the hot side of the line cord of a regular 2 tube
shop light and the whole thing, ballast and all is about 0.48-49 amps
and a line voltage of 123 VAC so the whole thing is about 60 watts.
I am not sure where the "40w" comes from.
Maybe that was based on the old style magnetic ballast.
ok - was curious enogh to break out my Kill-A-Watt meter...
as the twin tube shop light is plugged into a switched outlet.
SO - the lamps are - F40RES SP41 40w
The meter shows the fixture with both tubes running -
124v .86amp 67watt 105va ..... that's 67watts total for BOTH running
Interesting. So I went out to my shop where I could conveniently measure
on four identical cheap shoplight fixtures all populated from the same
case of Sylvania Octron/Eco F032/T41/Eco 32W lamps. After a warmup
period I measured: 56W, 57W, 57W, 60W. So there is some variation and
all seem to be a bit below the 32W spec on the tube.
I'm guessing that is for the fixture - with two bulbs lit up -
BTW - looked up that various flavors of my F40's - looking for "lumens"
and they appear to supply.... 2600 - 3150 lumens -
so a lot of light for wattage used -
single F40 straight bulb
2600 lumens / 34 watts = 76 lumens per watt
a stanard 60watt CFL
900 lumens / 14 watts = 64 lumens per watt
Watts are a measure of power consumption, not light produced. What you need to
be looking at are lumens. Those old 40w 48" tubes lumen output varied, but 3200
lumens is a reasonable average. A 14w CFL produces about 800 lumens, which means
you'd need 4 of them to produce the same light as an old tube.
BTW - the current 48" tubes are 32 watts for a similar lumen output.
As you can see from other replies, they may not be a true 40W, but
they will use more power than the CFL. What you want to com pare
though, is the light output to see if it is the same.
At work we replaced some 1000W light with brighter 128W fluorescent.
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