Muck on flourescent fittings

Regular job at the local Uni is changing fluorescent tubes & starters. I've noticed that the fittings without covers tend to have more failed tubes than those with covers & I wondering if it could be gunk/muck/crap on the actual fitting. Changing the tube & starters doesn't always work.

Rather than waste tubes I'd like to try cleaning the contacts to see if that improves matters.

So, would a spray on electrical de greaser like this be best

formatting link
?_dyncharset=UTF-8&fh_search=electrical+cleanerOr an air duster like this
formatting link
?_dyncharset=UTF-8&fh_search=air+dusterNever used either before so I'd appreciate any advice.

Reply to
The Medway Handyman
Loading thread data ...

formatting link
?_dyncharset=UTF-8&fh_search=electrical+cleaner>

formatting link
?_dyncharset=UTF-8&fh_search=air+duster>

This isn't something I've come across before. I wouldn't use a degreaser unless the lights are somewhere where they are being exposed to grease, such as a poorly ventilated kitchen. If it is a contact contamination problem, it should only be dry dust otherwise.

Only other thought is the possibility of end caps which are failing in some way. Maybe damaged by heat from the tube or UV, or just had crappy contacts in the first place.

Reply to
Andrew Gabriel

It could simply be that the ones without covers are used in places that have a different pattern of use to those with covers. The life of a fluorescent lamp depends upon the length of time it is left on after being switched on - the burn time. The stated life is based upon a burn time of three hours. Longer burn times will increase the lamp life, while shorter will decrease it. Therefore, if you have two lamps that are switched on for 6 hours each day, but one is switched on in two three hour sessions, while the other runs for six hours continuously, the second will last about 20% longer. OTOH, if the first lamp is only run for three hours each day, it will last a great many days (running into months or years) more because the second is burning through its 20% longer life twice as fast each day.

Generally, lamp failure rates increase rapidly at around 60% - 70% of rated life, which is why many planned maintenance schedules go for mass lamp replacement at that point. However, lamps also reduce in light output with age and a planned maintenance programme based on minimal light loss might involve mass replacement as early as 40% of the rated life.

Colin Bignell

Reply to
nightjar

formatting link
?_dyncharset=UTF-8&fh_search=electrical+cleaner>>>> Or an air duster like this

formatting link
?_dyncharset=UTF-8&fh_search=air+duster>>>> This isn't something I've come across before.

Interesting. They are twin tube fittings. Often one tube is lit and the isn't. Swapping the tubes leaves you in the same situation, so it points at the contacts. At the moment I report the fitting as faulty & it goes on a list to be replaced by an electical contractor.

Reply to
The Medway Handyman

Thanks for that Colin. All of the lights are on mechanical 'push switches' & stay on for about 5 mins. The buildings are 4 storey & its always the ground floor - the entrance - that the tubes go more often.

Reply to
The Medway Handyman

The Medway Handyman explained on 13/02/2009 :

Frequent switching will kill them quite rapidly. I once read that if a tube is turned on, it should for best economy and life it should normally be left on for at least an hour. It does sound as if the more frequently switched lamps are dieing as a result of the frequent switching. Could these not be altered to remain on for an hour, once triggered? Suggest occupation sensors(PIR's), combined with lighting level detectors to detect if there is a need for light.

Reply to
Harry Bloomfield

they would do, they see much more use

a very persistent myth

NT

Reply to
meow2222

Tube life is calculated at 3 hours per switchon, and more frequent switching will tend to cause shorter tube life. The quality and type of control gear can have a major effect here, but it's pretty much impossible to find out data of this nature relating to control gear or luminares before buying them, so that's slightly hit and miss.

Working out the break-even timing is quite an interesting calculation commercially, where you have to include the relamping cost (i.e. paying for Dave;-)

We have a scheme which is computer controlled and learns how the areas of the building are typically used. It used to be managed remotely, but I don't think the company which installed/managed it still exists. It runs on old PC's running OS/2, which fortunately just seemed to go on and on without needing any attention. Must admit I haven't taken a look in a few years, and it might have all been changed by now.

Reply to
Andrew Gabriel

It's colder at the bottom of the stairs and near the front door?

Owain

Reply to
Owain

Owain brought next idea :

...Which means the colder atmosphere plus the more frequent switching, will take more out of the fitting and lamp than it normally would.

Reply to
Harry Bloomfield

snipped-for-privacy@care2.com pretended :

Wrong answer!

Reply to
Harry Bloomfield

It looks like the first is a fairly standard "Switch Cleaner" type product and could well be worth a go. As you say in another post that the worst are in the entrance area, could it be that the fittings are subject to a colder and damper environment, which could cause some oxodising of the contacts. If that is the case, the cleaner may well help.We used it a lot in equipment subject to some seawater exposure.

Reply to
Old Git

The formula for fluorescent lamp life is

Actual Lamp Life = Rated Lamp Life x f(u) where, f(u) = 1.71 (1-exp[-(u/3.89)^0.505]) and u = burning cycle, hours of operation per start

With u = 5 minutes = .0833 hours, that gives the expected lamp life to be about 23% of the rated life. However, increasing the cycle time to 10 minutes would only increase the life to 32% of the rated life. Therefore, unless it resulted in them being turned on less often, there is nothing to be gained by doing that, as they would actually burn out quicker, in terms of days between lamp changes..

As other have pointed out, other factors, such as ambient temperature and the type of starter and quality of the fittings, will affect the life too, so the formula is only useful for comparing different switching times in the same fitting.

Colin Bignell

Reply to
nightjar

In a stairwell, which is what this sounds like, it is usual for all the lights to be turned on together, so it is probably some other factor - lower ambient temperature near the entrance has been suggested.

Colin Bignell

Reply to
nightjar

Its 4 floors, each landing has its own set of lights & switches. You enter & push the switch which turns on the ground floor lights, then push the switch on each floor as you go up. The lights overlap IYSWIM.

Reply to
The Medway Handyman

The lower the floor, the greater the use, with the ground floor having greater exposure to varying conditions - outside temperatures and therefore greater swings in temperature and humidity?

Reply to
Clot

All the student accom blocks I've been seen - built from the sixties to the nineties - have had maintained ELUs on 24 hours a day, even in daylight with ample windows.

A problem with the timer switches is that the lights turn off suddenly, which is a hazard if someone is in mid step.

I do wonder if not having permanently-on lighting is compliant with the fire regs.

Owain

Reply to
Owain

All the lights I've ever experienced turn off suddenly.

Reply to
Gib Bogle

Then you have your answer - the entrance lights get used more. However, like Owain, I'm not sure they shouldn't have continuous lighting to meet fire regulations, although I would have though dusk to dawn would be sufficient..

Colin Bignell

Reply to
nightjar

House lights in theatres don't

Owain

Reply to
Owain

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.