halogen lv transformers

[mark1967]

i have recently installed 10 x 35watt lv halogen down lights in my kitchen
all wired with individual transformers
every couple of weeks a transformer blows
i have replaced them at the shop i got them but they still blow
am i just unlucky or are the transformers rubbish. they are green brook selv halogen transformers dimmable model et60t-3.

also they are on a dimmer which buzzes when on half way i think this is normal but there is a buzzing in the fuse box as well. is this normal?
thanks for any help

 

[Observer]

I gave up with trying to dim ELV halogen - couldn't stand the buzzing (from the dimmer/switch, not the fusebox/CU). I have ~50 ELV halogens in my kitchen (large kitchen with dining and 'family' areas), nearly all on individual transformers. Some (along line of worktops) are 50W and the rest are 20W. Different lighting levels are achieved by switching -

Worktop lights (all 50W)
Main area (all 20W)
Under cupboard (all 20W)
Display cupboards (all 20W)
Dining area (20W)
Family area downlights (20W)
Family area wall lights (60W tungsten)

So I can achieve various lighting levels simply by differential switching.

I also have another ~30 or so in aother areas of the house - again a mix of 20W and 50W. All my ELV halogens have been installed for 6-8 years and I have had no more than about 6 transformers fail in that time.

All of the transformers are TLC's standard brand and the lamps are now only ~£1.20 each (compared to GU10 lamps which are ~£4.50).

I'd say definitely something wrong with the transformers or the installation (air space round them?)

 

[Steve]

Observer, please read this.

50 lights at average 30 watts is 1500 watts. I think you can find some lights in your kitchen to replace with LEDs and CFLs.

If you cant I'll eat my hat.

In the past most homes were lit by less than 1000 watts of light. You simply cannot justify using that much light in one room.

And the best light for under cupboards (which you cannot see anyway!!!) is fluorescent striplights.

 

[Observer]

Observer, please read this.

50 lights at average 30 watts is 1500 watts. I think you can find some lights in your kitchen to replace with LEDs and CFLs.

If you cant I'll eat my hat.

In the past most homes were lit by less than 1000 watts of light. You simply cannot justify using that much light in one room.

And the best light for under cupboards (which you cannot see anyway!!!) is fluorescent striplights.

Steve,

I can see what you're saying.

I've done an exact count now and I have 53 light sources in the kitchen - 13 x 50W ELV, 38 x 20W ELV, 2 x 60W tungsten. That does seem a lot (even for a large, triple aspect room) but I never have all the lights on at the same time.

I'm sure, if I did replace all of the fittings, I'd see substantial energy saving - but:

1. Looking at costs: if we take the price of a replacement 9W fitting (incl. lamp) at £10, that's the equivalent of ~120 kW/h. At 8.33p per kW/h, the payback period is ~3000 hours against a 50W halogen and ~11000 hours against a 20W halogen. At (say) 3 hours a day that's ~3 years and ~10 years respectively. That's before lamp replacement costs which are £1.25 for a halogen and ~£6.88 for a 9W Megaman CFL.

2. All of the cutouts are 80mm so too big for the CFL fittings anyway.

So - nice idea but replacing existing fittings (before they would need to be replaced anyway) just doesn't add up.

 

[mark1967]

thanks for reply
another 2 transformers went yesterday
the air space around them is ok they are inbetween joists in celing void and i used aliminium coated halogens that throw heat downwards.

i did the same thing in a previous house but used different transformers and had no probs.

i just wanted to know if anybody had probs with these green brook transformers before

thanks

 

[fastJedi]

Youre one step ahead of me! Whatever you do, dont buy any from Screwfix. I have swapped a 60VA one 3 times, and still not got one that works!!!!

 

[mark1967]

thanks for info

does any body know where i can get or recommend some decent transformers

 

[followgers]

I would say first of all check that the Transformers are suitable to be dimmed. I have replaced so many of those green brooks before. TLC standard are a good bet. If not Aurora havn't failed me before. If it is still happening after the change over, try swapping the dimmer or reverting back to standard switch (and get rid of that damned buzzing!!).

 

[DESL]

but there is a buzzing in the fuse box as well. is this normal?

No - could be a number of things from the meter to a loose connection somewhere.

Switch off each cct in turn to determine which if any of the ccts it's on.

Have you checked the rating on the ELV transformers as some give a fixed value and some will state 20 - 50 W. The fixed rating trannies don't like being run on a lower load.

 

[mark1967]

thanks for replys

the tranys are dimmable and 20-60 va
i will now try a different make

the dimmer switch is new and has a 1000watt rating
the fuse box only buzzes when the dimmer switch is half dimmed its ok when turned on full.
all the wiring is tight and seems ok.i might switch back to standard switch and bin the dimmer