Office Lighting - question

[TheVictorian]

In my office we have a suspended ceiling with probably 30 light fittings similar to:

http://www.tlc-direct.co.uk/Products/MDIL255PL.html

each containing 2 x 55w PL-L Lamp 4 pin like these:

http://www.tlc-direct.co.uk/Products/LAPLL55CW.html

Every time one bulb goes, which seems fairly often, it causes both bulbs to go off. Our electrician then pops in, and swaps BOTH bulbs for new ones, despite the fact that one of the bulbs is working fine (I know this as both come on as soon as the fauly one is replaced).

Is it good practise to replace both bulbs or are we being diddled? The electrician didn't do one light today as he hadn't enough bulbs with him and will come back, probably charging a call back, despite the fact that 50% of the old bulbs he took away are fine.

 

[Iggifer]

I personally change both, usually because the old tube that still works has lost an fair percentage of its brightness and if it's only going to fail in a few weeks / a month anyway then it may as well be done now

If you always do them together you know they're gonna fail pretty close to each other

It's not necessary to change both though

 

[Johnmelad]

Why are you paying an electrician to change a tube?

The working tube could last months, so no need to swap out.

 

[TheVictorian]

Thanks - that makes sense and is fine as long as they are charging £4 a bulb rather than £20!

 

[TheVictorian]

I'm not paying anyone to change a tube, the people who are responsible for running the building are - I just wanted to see what the best practise is.

For the record I would more than happily get up a ladder and change the tube, however it isn't really my job, I'd get my suit grubby and the powers that be would worry about insurance etc etc.

 

[Iggifer]

I take it he does charge £4 / tube?

Even that is a little expensive but better than £20

 

[TheVictorian]

I don't see the invoices to be honest, but I have raised the question.

 

[Lectrician]

It is common to change both tubes, not just the one. Just as with older fittings with starters, both the tube and starter will be changed as a pair.

Infact, if you go by the book, you would be changing the lamps at the recommended interval BEFORE they fail, or even become dimmer!

 

[RF Lighting]

Many manufacutrers recommend that both tubes are replaced upon failure of one. If the fitting is switch start, the starters should also be replaced at the same time.

Dead tubes can damage HF control gear.

Your electrician is not diddling you. He is doing his job properly.

 

[SimonH2]

It's noticeable that if you replace one tube in a multi-tube fitting, you can see a distinct difference in brightness - the new tube is usually significantly brighter. I've heard that electronic control gear reduces this effect, but I've never worked anywhere that'll splash out like that so I've only worked under switch-start fittings.

As Lectrician says, in a properly run facility, it's normal to replace all the tubes on a scheduled basis due to the reduction in output with time. Of course it also varies with situation - in some cases it's not easy/convenient/cheap to access one fitting to change a single tube - so having a schedule means that mostly you'll be replacing them before they start failing and needing expensive ad-hoc replacements.