Flourecent Efficiancy???

[Clark]

An electrician once told me you are better off to leave your flourecent lghts on if you are just leaving the garage for a little while. He said they use the same amount of power in 8 hours as it takes to turn them on.

Is this BS or fact?
Clark

 

[JCByrd24]

That doesn't pass the straight face test for me. Yes they don't last as long being turned on and off compared to being left on, but I don't see where 8 hours worth of power is going (being used) in 10 seconds. If I had a "Kill-a-watt" power meter I would test it for you, but I haven't gotten one yet.

 

[BioHazard]

Completely, totally, 100% full fresh bull ****. In fact it scares me if an "electrician" actually said that.

8 hours with my lights would be around 20 kilowatts. NO WAY IN HELL do they use that much starting up. The startup amp draw is rather low, and the peak is VERY short - without doing the math I'd say you burn about 1 or 2 watts extra by turning the lights on. You save a lot more than that just turning them off for 5 minutes.

Metal halide lights that need time to warmup are different, they do use a lot more juice to start up, but still NOWHERE NEAR 8 hours worth.

 

[socketjockey]

Live Large...leave 'em on.

 

[BioHazard]

Live Large...leave 'em on.

Most the time with flourescents, yeah. They live longer (both ballasts and tubes) the less on/off cycles they have.

In my garage I have a 15 watt CFL bulb that I leave on 24/7 as a night light. It's been on since 2001. The rated life hours for most CFLs are around 7-10,000 hours - 2001 was something like 78,000 hours ago and the bulb is still burning bright!

I put the same bulbs in the lights on the ceiling, always being turned off and on. They only lasted a few months, after about 6 bulbs I said screw it and went back to incandescents...

 

[ddawg16]

Mythbusters did a story on that one.....TOTAL BS.....the current surge lasted about 50ms.....

So....the only advantage to leaving the lights on is the On/Off issue that can effect some lights. It's not the actual light but rather the electronics.

Personally....if the light is going to be off for less than 5 min....yea, most likely better off just leaving them on.....

For what it's worth (FWIW for you texting types)...I have 2 CFL's in the garage door opener....as you know the lights come on every time something trips the beam when the door is open....and pisses me off...I wish I could turn off that feature....

Anyway...on a typical weekend, those lights will go on and off dozens of times....after a year...no issues...I don't recall incandescents lasting that long....

 

[BioHazard]

Yeah, CFLs, and even tubes/ballsts can be pretty hit and miss. Some last a week, if that. Some last forever. I have another CFL out on the back porch I think I spent $1 on...on/off every night, outdoors, for at least 3-4 years now.

I bought a pack of reflector/flood CFLs for can lights in my kitchen at costco for like $4 after a rebate from the local utility. Six lights all burned out within a week of each other after a few months. I bought some more expensive ones at home depot, they've worked fine for many months. Maybe it's a heat issue in the cans...

You really have to wonder how much we're "saving the environment" with these damn things, when I have to throw away more than 50% of them after a very short time. Not to mention the toxic contents...

....and pisses me off...I wish I could turn off that feature....

I'm building my own cable driven door opener for my shop. No lights, no sensors. If there's something in the way of the door, it will just cut it in half.

My garage door opener at home has the same incandescent bulb in it as when I moved in 10 years ago...but I guess that's 'cause I never open that door because I'm too embarresed to let the neighbors see inside.

 

[sams]

I think mythbusters came to the conclusion if you have your lights turned off and on it uses about 3 seconds of electricity or something like that.

 

[y20dth]

I think mythbusters came to the conclusion if you have your lights turned off and on it uses about 3 seconds of electricity or something like that.

Personally, I think the light uses electricity as long as they are on.

 

[ixlr8]

If I had a "Kill-a-watt" power meter I would test it for you, but I haven't gotten one yet.

Most libraries have the "kill-a-watt" meters available for 'signout'. Even in our little town of 1300 residents, the library has 2 available.

 

[kizer]

I have 9 T8 Fixtures in my garage and honestly I would only leave them on if I ran into the house for a quick visit. Dinner and everything else I turn them off. There is no way in heck that I would use less electricity leaving them on than turning them off.

I've yet to change my bulbs since I've installed them in 2003 or maybe 2004. I turn them on when I need to and turn them off when I do not.

 

[MattT]

They live longer (both ballasts and tubes) the less on/off cycles they have.

That's the only reason to leave 'em on. Switching them off for short periods will end up costing $$ in new ballasts and tubes which might outweigh the electricity saved. The replacement hassle also needs to be figured in. With an 8' ceiling it's no biggie but if the fixtures are 20' up ..........

 

[jvitez]

It's not the electricity use that matters, it the lamp life. Check out lamp manufacturer's websites. Lamp=bulb BTW. Most will say lamp longevity will be reduced if you leave tubular fluorescents on for less than 3-4 hours at a time. It's not the extra electricity that matters, it the lamp replacement.

 

[BioHazard]

I believe the "standard" for figuring bulb life hours is 3 hours per cycle. With T8s that's around 28,000 hours or more. If you leave them on for 8 hours a day, or, say 24 hours a day like a grocery store, they will last nearly forever. Or at least until T8s become outdated.

With an 8' ceiling it's no biggie but if the fixtures are 20' up ..........

Yeah, that's something I never though of before I moved into my last shop. 20+ finished ceilings with metal halides in the center...how the hell do I change that?

The business across from me does nothing but service lights with a bucket truck and other lifts. They've got a really good thing going on there, with contracts with local business...

 

[PassnThru]

Mythbusters did a story on that one.....TOTAL BS.....the current surge lasted about 50ms.....

So....the only advantage to leaving the lights on is the On/Off issue that can effect some lights. It's not the actual light but rather the electronics.

Personally....if the light is going to be off for less than 5 min....yea, most likely better off just leaving them on.....

For what it's worth (FWIW for you texting types)...I have 2 CFL's in the garage door opener....as you know the lights come on every time something trips the beam when the door is open....and pisses me off...I wish I could turn off that feature....

Anyway...on a typical weekend, those lights will go on and off dozens of times....after a year...no issues...I don't recall incandescents lasting that long....

All three of my openers (Craftsman) have that feature and I have disabled it on all of them. I don't remember exactly how I did it but it was in the manual. I believe I had to start with the light off, hit and hold the light switch on the console until the lights flashed, and then let go. They would not come on from then on when you walked through the sensor beam. That may not be it - if you can't find it in your manual let me know and I'll look up the procedure for mine when I get home.

 

[Costner]

I bought a pack of reflector/flood CFLs for can lights in my kitchen at costco for like $4 after a rebate from the local utility. Six lights all burned out within a week of each other after a few months. I bought some more expensive ones at home depot, they've worked fine for many months. Maybe it's a heat issue in the cans...

It is - most CFLs are not rated for use in recessed can lights. You need to buy the CFLS that are specifically rated for this purpose... otherwise you will experience decreased lifespan.

However in your case considering they all seemed to burn out within a week of one another I suspect the culprit may have been either a surge or a brown out which took a toll on the electronic ballasts in the bulbs. I just don't see how their production tolerances are perfected to the point the bulbs all last the same amount of time... that would be almost impossible.

You really have to wonder how much we're "saving the environment" with these damn things, when I have to throw away more than 50% of them after a very short time. Not to mention the toxic contents...

You have a valid point, but I should note that many areas accept CFLs (and all fluorescent bulbs) for recycling, so they can capture the mercury used inside of them. Also, I once read a very detailed article which showed how the amount of mercury used inside of a CFL - even if it was tossed in a landfill and wasn't recycled - was still less than the amount released by a coal fire powered plant to produce the electricity which would have been used by a standard incandescent bulb.

All that aside, even if they aren't better for the environment or even if it was a straight wash... they are still better for the old pocketbook. Depending upon usage CFLs can pay for themselves in a few short years or in some cases even a few months.

You can use a savings calculator like this one to figure it out, but in my case I figured when I bought the CFLs on clearance they paid for themselves in about six months. Anything after that is pure gravy.

http://www.energystar.gov/ia/business/bulk_purchasing/bpsavings_calc/CalculatorCFLs.xls

 

[BioHazard]

You have a valid point, but I should note that many areas accept CFLs (and all fluorescent bulbs) for recycling, so they can capture the mercury used inside of them.

Then you have to add in the gas burned to get to the recycling center. Local garbage services should start allowing you to recycle CFLs with your other recycleables. Around here I think places like Home Depot take the little CFLs for free, but I have to pay about as much as a new tube to dispose of an 8' T12. (now you know why my attic is full of burned out tubes) And I wonder how many people even bother?

They will definately save you money, in the right places. In my shop it's over 2kw just to flip on one light switch, so I've got CFLs everywhere. But places like my bedroom, closets, other low useage areas it's hard to beat a good ol' 60w bulb.

I can't wait until they come out with LEDs that can compete with fluorescents. Nothing toxic what so ever. Not even any glass to break. I bought a GE 10 watt LED can light bulb (par 38) and it is amazing - too bad it cost $50.

 

[Costner]

I agree - LEDs are obviously the future of lighting, but it will be several years before the pricepoints get down to CFL territory.

I wonder if my stockpile of CFL bulbs will be burned out by then? Come to think of it - I may never have to buy another CFL in my life!

 

[Privatejoker]

White LEDs are more efficient than incandescent bulbs, but not CFLs. The LEDs efficiency comes from the narrow band of light they can produce, ie red, green, amber. White light is a combination off all the colors, hence the loss in efficiency.

 

[ddawg16]

CFL vs LED is an ongoing discussion....I think overall, the LED is slight more effecient....but, when you roll in the total power usage (heat loss in electronics)...it's a close race....at low voltage (22v and less), Flurescent can't keep up....but at 120/240....LED is just not there yet....

Here is a good chart the compares relative efficiency of all lights....I'm not quite sure I totally buy the actual #'s....I think they might be 'fudging' a little...I think they are pushing linear tubes....

http://www.mge.com/home/appliances/lighting/comparison.htm

 

[sams]

also I dont know about you guys but I have found the light output of LED's drop really quickly despite how they are meant to last forever. That and the very high purchase price.

 

[Brandon_K]

Metal halide lights that need time to warmup are different, they do use a lot more juice to start up, but still NOWHERE NEAR 8 hours worth.

While this is true with some older MH ballasts, the newer types, especiall pulse-start (aka pulse-strike) actually use LESS current at startup. My 400w MH's will startup with an inrush current of ~1.4A (per leg, 240v) and gradually rise to 2.0A per leg (maybe over 5-8 min) at which point it will flatline.

 

[BioHazard]

While this is true with some older MH ballasts, the newer types, especiall pulse-start (aka pulse-strike) actually use LESS current at startup. My 400w MH's will startup with an inrush current of ~1.4A (per leg, 240v) and gradually rise to 2.0A per leg (maybe over 5-8 min) at which point it will flatline.

Interesting...I guess that's why non pulse starts are illegal for new installations here...

 

[Brandon_K]

Interesting...I guess that's why non pulse starts are illegal for new installations here...

Really? That's interesting. I wasn't aware they were being outlawed anywhere. My supply house still has a bit of non-PS stuff. Where is here anyhow?