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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Compact Flourescents https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1233627441 Message started by RobS on Feb 3^rd, 2009, 2:17am

Title: Compact Flourescents
Post by RobS on Feb 3^rd, 2009, 2:17am

I have recently had some stables built. The electrics were installed and tested to Part P as the supply is taken from the house. One of the circuits consists of 10 x 18W compact flourescent recessed downlighters. The lights are IP66 and designed to be used in sofits. The lights are switch with by either a MK Masterseal 2-way switch, a MK Masterseal Intermediate switch or a remote 2-way switch (EasySwitch). The EasySwitch is just a relay with a pair of NC and NO contacts driven by the wireless receiver.

After the lights had been working for a couple of weeks they stopped working one by one. So far 2 of the electronic HF ballasts have failed and in total 7 bulbs. I have tried a mixture of Philips and Sylvania bulbs.

With 5 working when I switch, on the voltage measured between the live and neutral conductors by one of the fittings rises to 250V and then decays slowly to 230V.

Any ideas what is causing the failures?

Title: Re: Compact Flourescents
Post by LSpark on Feb 3^rd, 2009, 8:25pm

What brand is the downlights, and is the HF gear built in or attached separately? Do you know the brand of HF gear, is it definatly HF type?

Is the shed insulated, what is the ambient temperature like?

Do you know if the HF gear is pre-heat or cold-start?

Fluorescent lamps in general don't like it cold, in fact they operate at best luminous flux (light output) in a very narrow range of temperature. But certainly they don’t like it too cold, the cold will shorten their life, and switching them on and off repeatedly will shorten their life even further.

Always run your fluorescent for a minimum of 20-30mins at a time.

I presume all the wiring is correct and there are no issues?

Title: Re: Compact Flourescents
Post by RobS on Feb 4^th, 2009, 12:34am

Thanks for the reply LS

The units are made by Illuma and the ballasts are Vossloh-Schwabe. I have spoken to both the companies who are helpful, but haven't thought of a good reason.

The stables aren't insulated, but have a tiled roof. They units probably see ambient so anything down to minus 5 C.

The HF ballasts have a pre-heat cycle of 1-1.5 seconds. Sylvania suggest that the minimum temperature that their lamps are suitable to are governed by the ballast suppliers recomendation. Vossloh-Schwabe suggest that their ballasts are Ok to minus 15 C. Philips don't quote a minimum temperature, but suggest they are ok for externsl use.

The failures did appear temperature related, but none have failed during this week's cold spell, but only 5 are working.

Wiring I think is OK. Both the electrician and myself have looked at it and can't see any issues. Testing didn't show any issues.

Title: Re: Compact Flourescents
Post by CWatters on Feb 4^th, 2009, 8:21am

Pehaps check the earthing. I recall reading somewhere that good earthing of the metal parts of the fitting is required or higher voltages are need to get the tubes to strike.

Title: Re: Compact Flourescents
Post by RobS on Feb 4^th, 2009, 1:09pm

Not on this fitting. The "earth" wire is terminated in the connection block, but nothing connects to it. The ballasts only have a live and neutral feed.

Title: Re: Compact Flourescents
Post by Zambezi on Feb 4^th, 2009, 1:26pm

This is a long shot but could you try splitting the circuit into 2 so that you only have 5 on each? It may be inrush currents etc destroying them prematurely. I have also been told CFLs don't like the cold but you say they should be good to -15C so I guess that cancels that one out...

Title: Re: Compact Flourescents
Post by Goodsparks on Feb 4^th, 2009, 2:12pm

Vossloh gear is good usually, certainly up there with Tridonic or Philips.
Could be that there is condensation forming within the control gear given the running temperature and very low ambient.

HF gear tends to be fairly resiliant, most being european has an operating voltage of 230 as opposed to the 240 we supply it with, I have had philips gear running at 250v + on a variac for a few weeks to test and all worked fine. (Didn't have any effect on consumption contrary to the information from Powerperfector)

Paul

Title: Re: Compact Flourescents
Post by LSpark on Feb 4^th, 2009, 9:19pm

wrote on Feb 4^th, 2009, 1:26pm:

It may be inrush currents etc destroying them prematurely

It's unlikely, ballasts such as them are designed for working in reasonable numbers, certainly 10 should not be an issue. However one should not mix electromagnetic ballasts and HF type ballasts as the inrush from the former can damage the latter. But if it's all HF there shouldn't be a problem.

wrote on Feb 4^th, 2009, 2:12pm:

Vossloh gear is good usually, certainly up there with Tridonic or Philips

VS gear is of reasonable quality, but I don't think compareable to the quality of philips "performer" range. VS is normally put into cheap fittings in my experience. Tridonic is a brand all of it's own.

wrote on Feb 4^th, 2009, 2:12pm:

HF gear tends to be fairly resiliant, most being european has an operating voltage of 230 as opposed to the 240 we supply it with, I have had philips gear running at 250v + on a variac for a few weeks to test and all worked fine

You will do, in fact you can run many ballasts between about 198V and 250V, they have some superior electronics in them that's for sure. Very stable against mains fluctuations normally.

It sounds likely that condensation could be the problem, as you state. Maybe there are a few duff ones, it can happen with anything, but dissapointing to have more than one fail.

Rob, when the lamps go, do they appear blackened on removal? or do they glow dull purple when in the fitting?

Title: Re: Compact Flourescents
Post by sparky415 on Feb 4^th, 2009, 9:31pm

A silly idea Rob but the fittings are rated at 18w I know some lamps/fittings are interchangeable and some are not
Might just be a silly idea :-/

Title: Re: Compact Flourescents
Post by LSpark on Feb 4^th, 2009, 9:38pm

I think 18W 4-Pin has it's own set cap of G24q-2.

From information here, and for reference (4-Pin)

10 & 13W are G24q-1
18W is G24q-2
and 26W is G24q-3

2-Pin variants have different cap & pin configuration (obviously), and
the higher wattages are a different shape altogether.

It's one of them problems where you wish you could be there to see it for yourself and make a judgement!

Title: Re: Compact Flourescents
Post by sparky415 on Feb 4^th, 2009, 9:46pm

I know I have had some confusion in the past with compact fittings :-[

Title: Re: Compact Flourescents
Post by LSpark on Feb 4^th, 2009, 10:57pm

There's quite a large range of pin-based CFL's so it's not surprising.

Title: Re: Compact Flourescents
Post by RobS on Feb 5^th, 2009, 2:03am

Thanks for all the replies. I haven't seen any evidence of condensation, but will keep an eye on this.

The bulbs are a mixture of Sylvania and Philips. I have checked with the lamp supplier and the bulb supplier that they are the correct ones (PLC G24q-2 18W 4 pin).

When the bulbs fail they just stop working. I can't remeber seeing any fail when lit. When they fail they eitherb just don't light up or there is an orange glow for a few seconds before going out. The bulbs look new when they fail - no evidence of any burning.

With the cold weather I was expecting a few more to go, but currently none have.

Rob

Title: Re: Compact Flourescents
Post by LSpark on Feb 5^th, 2009, 10:16pm

Strange phenomena’s.. I reckon you've got aliens coming down in the surrounding fields at night and blasting them with EM radiation :P

Title: Re: Compact Flourescents
Post by CWatters on Feb 6^th, 2009, 9:29am

Sorry if this is stupid but .. How are you testing for failed bulbs and ballasts? Is it possible they are just failing to strike in the cold and haven't actually failed? Can you check some of the failed ballasts indoors in the warm?

Title: Re: Compact Flourescents
Post by WOLF on Feb 6^th, 2009, 11:03am

your all wrong, its the bloody horses lossening the lamps in the fittings!!!

(sorry)

Title: Re: Compact Flourescents
Post by Zambezi on Feb 6^th, 2009, 11:07am

Have you tried lagging the cables? ;D ;D ;D Sorry Wolf started it!

Title: Re: Compact Flourescents
Post by LSpark on Feb 7^th, 2009, 4:01am

Good advice CW, as I said before it's tricky to know without looking at it. Best advice is to call in an electrician and get it all checked out.

Title: Re: Compact Flourescents
Post by RobS on Feb 11^th, 2009, 8:52pm

I have tested the ballasts by trying a bulb that starts in other ballasts, but not in the faile ones. I have also tried inside the house. I have had 5 lights woking for the last few weeks even during the cold weather so I don't think it is temperature related. I have got a new set of bulbs and ballasts so will replace them all and try again. The only thing I will do is check the transient voltage during switch-on.

Thanks for all your help.

Title: Re: Compact Flourescents
Post by LSpark on Feb 11^th, 2009, 9:09pm

The only voltage your really interested in is the nominal voltage, which will fluctuate. They should have inbuilt surge protection if they are of good quality. I would certainly be wary about replacing them with the same make if you can help it.

Title: Re: Compact Flourescents
Post by Zambezi on Feb 25^th, 2009, 4:42pm

I spoke to a guy today, who owns a shop that does Eco lighting (CFLs and LEDs). He said he would not recommend using standard CFL fittings outside.
They sell "external" fittings that keep the lamps ticking over at about 10% and then when the PIR/microwave picks up movement they ramp up to 100% brightness (they call it Lux Up technology). I guess the theory is that they are not starting up from cold each time and they keep themselves warmish.

They do a range of 18W pl-t CFL downlighters for internal use that can be dimmed (not a standard dimmer but uses standard wiring), up to 10 fittings on 1 dimmer switch. Which is a nice alternative to halogen spots.
www.greenlighting.co.uk

Title: Re: Compact Flourescents
Post by LSpark on Feb 25^th, 2009, 4:53pm

There is probably truth in that suggestions Zamb, but bear in mind thousands of CFL's operate happily outside in the cold. The key point which can't be stressed enough is that they DONT like being switched on and off, particualrly in the cold.

If you bear that in mind then there is no problem, CFL is ideal for good bright economical light that is going to be on say 2-3 hours in one go, preferably longer. Anything else short duration, sensor activation etc then forget it.. has to be an alternative e.g. halogen/tungsten.

Title: Re: Compact Flourescents
Post by RobS on Mar 2^nd, 2009, 12:28am

I replaced all the ballasts (with the same make) and the bulbs. No failures yet!

Title: Re: Compact Flourescents
Post by LSpark on Mar 2^nd, 2009, 1:11am

Let us know how you get on, particuarly if you have anymore problems etc!, but fingers crossed!

Title: Re: Compact Flourescents
Post by RobS on Mar 9^th, 2009, 1:49pm

Well everything is still working OK. Not sure what the cause was, but the only thing I can think of is the electrician didn't disconect the lights and did a resistance test. When I spoke to him he assured me that he didn't do anything which could have caused it. Alternatively there could have been a faulty ballast causing the problem. Eitehr way so far so good!