Help! Lighting problem...

[dvdsubtitles]

Hi all,

Got a bit of a problem with the lighting in my living room. I think it's just a basic electrical problem, hope someone can help.

Basically I have a lighting unit on the ceiling with four 50W halogen lamps. There is twin switch setup, with an on/off switch at one end of the room, and a dimmer switch at the other end of the room. This has been working perfectly for the last few months, with the dimmer providing the 'mood' lighting for watching movies, snogging the missus, etc.

A few weeks ago, I switched the lights on and one of the Halogen bulbs blew. The lights went out in the entire flat. Put in some new fuse wire in the fusebox, lighting comes back on. In the living room, 3 of the halogen lights are on full brightness, one is dead. The on/off switch works, the dimmer switch does NOT work - It will push on/off but the lights will not dim when turning the knob. Replaced dead bulb with new one. Dimmer switch still not working.

Concluded that dimmer switch must have blown - so, went out to B&Q, bought new dimmer switch (it is rated at 450W). Cost £20 (bloody expensive). Fitted new switch, all works perfectly - back to normal.

However, last weekend it's happened AGAIN. Exactly the same - another bulb in the lighting unit has blown, main lighting fuse has blown, dimmer switch blown. I don't want to spend £20 on a new dimmer every time a bulb blows!!

Any ideas what is causing the dimmer switch to blow, and how can I protect it? Do I need a dimmer with a higher power rating? Help....!

Cheers,
Mat

[dvdsubtitles]

Isn't there ANYONE here who might have some suggestions?

[andybed]

Think I have heard of this happening before. When the lamp blows it takes out dimmer, hence dimmers have to be derated. But if your dimmer is 450w and lights are 200w this should be ok IMO. I,m no electrician but but if you try the Screwfix forum you should get a more qualified answer to your problem.

http://www.screwfix.com/talk/index.j...orums&ts=33646

Good luck, Andy

[avanzato]

Are the halogen lights Mains or Low voltage. I think with the low voltage ones you have to make sure the dimmer can handle the transformer for the lights or it will over heat and go pop.

[dvdsubtitles]

Originally Posted by avanzato

Are the halogen lights Mains or Low voltage. I think with the low voltage ones you have to make sure the dimmer can handle the transformer for the lights or it will over heat and go pop.

This is unit I have, here.

These are 50W bulbs, I don't think they are low-voltage, I don't recall seeing a transformer in the unit. It's designed to directly replace a normal old-fashioned ceiling light, which is what I have done. The dimmer failure only occurs when one of the bulbs blows.

Mat

[dvdsubtitles]

Originally Posted by andybed

Think I have heard of this happening before. When the lamp blows it takes out dimmer, hence dimmers have to be derated. But if your dimmer is 450w and lights are 200w this should be ok IMO. I,m no electrician but but if you try the Screwfix forum you should get a more qualified answer to your problem.

http://www.screwfix.com/talk/index.j...orums&ts=33646

Good luck, Andy

Thanks, I'll check it out.

Cheers,
Mat

[avanzato]

The John Lewis description says High spot bulbs which should mean they're 230v mains, GU10 or GZ10 is that right? What brand is the Dimmer switch and how is it wired, 2 way I assume.

[dvdsubtitles]

Yes I am pretty sure they're 230v or 240v - this sounds familiar as I was out buying spare bulbs a few weeks ago.

Yes, the dimmer is wired 2-way. I'll try and find a linky to the dimmer specs...

[dvdsubtitles]

here you go:
http://www.tlc-direct.co.uk/Technica...lus_Dimmer.pdf

the model that I have is K1535 WHI - 1 gang, 2-way single dimmer switch, 60-450W.

[andybed]

From the spec sheet for your dimmer K1535 WHI which is a 'standard"sdimmer it states that its "only suitable for normal tungsten filament lamps with internal fuses", so if this is your dimmer its looks like it will not work with your light fitting and halogens.

Andy

[andybed]

It also states in the spec sheet that the Intelligent dimmer has 'soft start' which is beneficial with mains voltage halogens due to the high inrush current at switch on. Did your faults occur when you first switched on the lights?. If so, its probably the intelligent dimmer that you need.

Andy

[avanzato]

Yes I would agree as the text for the 'Intelligent Dimmer' on that MK info sheet says it is suitable for mains Halogen that it'll be OK for you. I would guess that the standard dimmer you have is going into 'Over Load protection' Mode 4 and shutting down as soon as the bulb goes. BTW is there a reset switch on the dimmer at all?

It is also just worth checking the wiring is done as per the diagram on that sheet for 2 way switching when you replace the switch.

[dvdsubtitles]

Originally Posted by avanzato

Yes I would agree as the text for the 'Intelligent Dimmer' on that MK info sheet says it is suitable for mains Halogen that it'll be OK for you.

I can't find this - I can only find a bit that says it is suitable for "low voltage Halogen bulbs". The bulbs I use are labelled GU10+C 240V 50W - these are not "low voltage" are they? I'm pretty sure there are no transformers within the lighting unit.

BTW is there a reset switch on the dimmer at all?

No, there definitely isn't.

We're getting there....

[avanzato]

GU10 are mains voltage and don't use a transformer so you're OK there. I'm inferring that as the specs for the intelligent dimmer have 'soft start' and that feature is beneficial to Mains Halogen use. Then the intelligent dimmer is in fact suitable to be used with mains halogen lights. Reading the sheet again it looks like the 4 modes of shut down also apply to the intelligent dimmer not the standard one as I first thought. The standard one just has a thermal cutout safety device.

I also found this on interDIY that explains why a bulb going pop trips the circuit breaker.

[dvdsubtitles]

Originally Posted by avanzato

GU10 are mains voltage and don't use a transformer so you're OK there. I'm inferring that as the specs for the intelligent dimmer have 'soft start' and that feature is beneficial to Mains Halogen use. Then the intelligent dimmer is in fact suitable to be used with mains halogen lights. Reading the sheet again it looks like the 4 modes of shut down also apply to the intelligent dimmer not the standard one as I first thought. The standard one just has a thermal cutout safety device.

I also found this on interDIY that explains why a bulb going pop trips the circuit breaker.

Right, yes I've managed to find the manufacturer's website and it does mention specifically on there that the intelligent dimmers are suitable for mains voltage halogens, so you were right.

However, getting one of these dimmers might be a bit of a palaver, so I'll call the manufacturers and find my nearest dealer.

I'm gonna do two things: get this new dimmer, and also get a plug-in circuit breaker to replace the lighting fuse wire in my current fuse box.

Thanks for all your help, much appreciated!!

Cheers,
Mat