F32T8 bulb life

[anythingyoucanimagine]

Says on the Phillips package:

"Rated average life at 12 hours per start on instant start ballasts. Average life under engineering data with lamps turned off and restarted once every 12 operating hours."

And:

"Lasts 8 years based upon 6 hours average usage per day/7 days per week."


I've got two of these light strips on a motion sensor. When the garage/house is done they will see normal use and the garage is small enough that once it is cleared out, the motion sensor switch should be able to sense movement within the whole garage.


Currently there's a bunch of **** (ladders, lumber, etc.) in various places so depending on where I am, the motion sensor lights will turn off. Is that frequent on/off cycling going to kill the bulbs? I upgraded to LED in my other garage so these lights were free (already owned them). That said, if I'm going to burn out T8 bulbs quickly then quick math says upgrading to LED might be worth it.


Thoughts? Thanks.

 

[pattenp]

The on and off does degrade the life of the lamp but the energy savings usually outweighs the slight shorter life due to the cycling on and off.

 

[cybrdyke]

They use 2 tests to determine life on instant start ballasts. One test is 12 hours on. The other test is 3 hours on.
Typical T8 lamp lives 30,000 hours if left on for 12 hours at a time, and 24,000 hours if left on for 3 hours at a time. Will your lights be on for that length of time?
Then, just to confuse you, they cite some other figure that totals 17,250 hours of life. No idea where they got that figure from.
So, divide those figures into how many hours you think you'll be using your lights in a year and you'll see how long they should last.
The motion sensor can possibly turn those lamps on/off more often than you might by doing it manually. Turning fluorescent lamps on and off is what shortens their life. So, a very active motion sensor will definitely shorten life.
LED tubes dont care about being turned on or off. It doesn't affect them the same way. Plus, they use half the energy of the fluorescents.
Good luck,
CD

 

[anythingyoucanimagine]

The motion sensor can possibly turn those lamps on/off more often than you might by doing it manually.

Yeah that's what I was getting at. I'm rewiring the house, have some structural stuff to fix, etc. (bought a POS vacation home, fixing it up) I'm in & out of the garage a lot. Maybe I'll take out the motion sensor and put in a switch for the time being. When I'm up there working, yes, I'd turn them on at probably 9-10am and leave them on until 9-10pm. Once the house is done it would be much shorter time frames (maybe 3hrs max) but it's also a vacation home.


Thanks.

 

[cybrdyke]

Yeah that's what I was getting at. I'm rewiring the house, have some structural stuff to fix, etc. (bought a POS vacation home, fixing it up) I'm in & out of the garage a lot. Maybe I'll take out the motion sensor and put in a switch for the time being. When I'm up there working, yes, I'd turn them on at probably 9-10am and leave them on until 9-10pm. Once the house is done it would be much shorter time frames (maybe 3hrs max) but it's also a vacation home.


Thanks.

A switch is smart if you are only in and out for a couple of minutes.
New sensors have really come a long way with what they can do. They have all kinds of features that will mitigate the amount of "on" time in any given space.
But for older sensors, some can be changed so that they stay "on" longer after they no longer see motion. This prevents them from switching on/off too often. Maybe there's some dip-switches hiding on it somewhere.
CD

 

[Bert_]

Instant start ballasts have no place in residential. They are fine in commercial and save a bit. When you switch an instant start ballast often it kills the lamps very early. Program start ballasts would be the correct choice here but none of the box stores ever carried them and even electrical supply's had to order them just because they cost a few dollars more.

 

[anythingyoucanimagine]

Instant start ballasts have no place in residential. They are fine in commercial and save a bit. When you switch an instant start ballast often it kills the lamps very early. Program start ballasts would be the correct choice here but none of the box stores ever carried them and even electrical supply's had to order them just because they cost a few dollars more.

The goal with the motion sensor/instant start is that laundry is in the garage. Motion sensor lets you walk in/out of the garage with a full laundry basket and not need to worry about the lights. Also, when we drive in, garage door opener has small light on it but then as we pull the car in the bigger lights turn on. It was supposed to be easy and convenient.


Again, seeing as this is vacation home, maybe I'll just switch it over to a traditional flip-switch for now, then put the motion sensor back in once the house is finished. Seems like they will last longer being on for 12-hours at a time vs. on/off/on/off, etc.

 

[Bert_]

The goal with the motion sensor/instant start is that laundry is in the garage. Motion sensor lets you walk in/out of the garage with a full laundry basket and not need to worry about the lights. Also, when we drive in, garage door opener has small light on it but then as we pull the car in the bigger lights turn on. It was supposed to be easy and convenient.


Again, seeing as this is vacation home, maybe I'll just switch it over to a traditional flip-switch for now, then put the motion sensor back in once the house is finished. Seems like they will last longer being on for 12-hours at a time vs. on/off/on/off, etc.

A few years ago I would have suggested you change to a program start ballast which would greatly extend the life of your T8 lamps with the frequent switching. Instant start is the "brute force" method of starting lamps, using a high voltage to start the lamp cold. Program start heats the cathodes or filaments before applying voltage so they are warm and starting doesn't wear them as much.

Anymore the LED tubes are cheap enough and so far don't seem to be effected by frequent switching.

 

[shoot summ]

I replaced mine with no ballast LED tubes from Amazon, so much better than the flourescent tubes...

 

[Falcon67]

I don't count on any of the "life" figures. I put 56 similar bulbs in when I built the shop in 2011, probably 1/3 didn't make it to 2017 when I changed it all over to LED. I just had a fairly new 460 lumen 3K LED bulb that was in a bath fixture burn out, less than a year old. Bottom line - quit worrying about it.

 

[sberry]

I kove motion for a couple places like that and would replace the fixture or lamp. There often is a switch for motions ahead of them, I always install one. Nothing to be saved here letting fixtures run all day so they don't have to be turned on a couple times. We kind of do that but its in dark shop and office where we have 13 watt running 24/7 to see our way around and use local lights when needed.