Lighting Circuit Question

[Kent A Bathurst]

I have a circuit - wired by an electrician - that includes 3 fixtures:

a 4-foot flourescent
an 8-foot flourescent
one incandescent - usually running 100w

2 switches on the circuit - one at the top of the stairs [where the incandescent is] and one by the back door. The 2 flourescents light the main aisleway through the shop. This circuit is by far the most-used lighting circuit in the shop - I have 5 other circuits that I wired, all flourescent fixtures, and each over specific work areas - on/off as needed. All flourescents are electronic ballast.

The doggone incandescent fries out more often than I'd think it should. Can't tell you the frequency exactly, but I'd guess every 6 months or so. The flourescents on the same circuit lasted probably 6 years, and which time I got a case, and replaced the entire shop. When I say "same circuit" I mean "dedicated 20a breaker". Nobody else drawing power from the box through that breaker.

My question: What the heck is going on here? Is it simply the effect of mixing flourescent and incandescent on the same circuit? Does this configuration somehow push surges through the incandescent that shortens its life? Or, is it a sign that there is something subtle in the wiring?

[Howard Acheson]

Possible issues.

o Bulb burning base up. Incandescent bulbs last longer when burning base down.
o Bulb in an enclosure that restricts heat dissipation.
o Frequent on/off cycles
o Vibration from walking above it or from equipment running
o Higher than nominal voltage in the circuit

One thing you can do is use a 130 volt bulb. It will burn cooler therefor longer lasting.

[David Dockstader]

Replace the incandescent with a CFL. Florescent bulbs just last a long time. My shop lights have been in 12 years and haven't been replaced yet.

[Kent A Bathurst]

Possible issues.

o Bulb burning base up. Incandescent bulbs last longer when burning base down.
Yep - it is your basic ceramic fixture attached to the ceiling of the stairwell
o Bulb in an enclosure that restricts heat dissipation.
The stairwell itself might qualify. Other than that, just a bare bulb in the fixture.
o Frequent on/off cycles
Maybe: 2 - 3 times per day. Total burn time is probably 12+ hours per day.
o Vibration from walking above it or from equipment running
Nope - empty attic above, no house mechanicals anywhere near, all the shop equipment is on the concrete floor of the basement at the bottom of the stairs.
o Higher than nominal voltage in the circuit
That one I can't answer.
One thing you can do is use a 130 volt bulb. It will burn cooler therefor longer lasting.
Didn't know there was such a thing. Neighborhood Ace Hardware, or do I gotta get from somewhere special?

Thanks, Howie

[Dan Friedrichs]

Well, 12 hours a day, 5 days a week, for 6 months, is 11k hours - quite a bit more than most incandescents are rated for. You're getting a good deal

You actually might be able to find a 130V bulb at Lowe's. You can check the voltage at the socket with a multimeter - if it's more than about 125V, that would be a factor that was significantly reducing your bulb life. Otherwise, replace it with a CFL.

[Kent A Bathurst]

Well, 12 hours a day, 5 days a week, for 6 months, is 11k hours - quite a bit more than most incandescents are rated for. You're getting a good deal

You actually might be able to find a 130V bulb at Lowe's. You can check the voltage at the socket with a multimeter - if it's more than about 125V, that would be a factor that was significantly reducing your bulb life. Otherwise, replace it with a CFL.

Ok, then - I'm fine. That is the one bulb in the house that gets toasted that often - but, it also burns way more than any other incandescent. Implied, but not stated, is that we use the door off the driveway a lot - and that circuit was laid out precisely to be the "safety" switch through the maze [aka shop] and up the stairs. And, I don't come down the stairs without a light, even if it is daytime - indoor, basement, clumsy....you get the picture.

"Shut up, and deal with it" is a reasonable response......

Don't have a multimeter. Don't need one for this purpose.

And - I'll start using those CFL things when they pry my large-volume toilet tank from my cold dead behind.

[Roger Myers]

Need to check your math...
12 hours per day for a full year (12x365) is 4380 hours...
Still, if used 12 hours per day, the usefull life is about right for many incand. And all the other points brought up are valid.
Roger

Well, 12 hours a day, 5 days a week, for 6 months, is 11k hours - quite a bit more than most incandescents are rated for. You're getting a good deal

You actually might be able to find a 130V bulb at Lowe's. You can check the voltage at the socket with a multimeter - if it's more than about 125V, that would be a factor that was significantly reducing your bulb life. Otherwise, replace it with a CFL.

[Dan Friedrichs]

Need to check your math...
12 hours per day for a full year (12x365) is 4380 hours...

Whoops - yep, I multiplied by days of the week then also days of the year. You're right.


They actually make some really impressive CFL's, now - take a look at this:
http://www.amazon.com/gp/product/B00...SIN=B000I17HUC