helogen light dimmer

[AndyJay]

Hi all
We're seen some lighting we like in a `next` store, but on the box it states that we need to use their dimmer switch because of the halogen bulbs. The dimmer switch doesn't match the ones we have so I'm wondering what and why we can't use a standard dimmer switch!
Any ideas?
Thanks

 

[ban-all-sheds]

You don't have to use theirs.

But you do have to use one which matches the leading-edge/trailing-edge characteristic of the transformer.

There is a compatibility issue with dimming ELV lighting "transformers" (in quotes because they aren't actually transformers, which is why the problem arises)

Dimmers do not work by lowering the peak voltage, they reduce the RMS voltage by simply chopping out part of the waveform - they either turn on part way through each cycle (leading edge, or phase-delay) or turn off part way through (trailing edge, or phase cut), and what the dimmer does must match what the transformer needs.

So you need to find out if that light needs a leading or trailing edge dimmer, and get the right sort.

 

[westie101]

characteristic of the transformer?

I see no mention of transformers in the OP, just halogen lighting.

 

[JohnW2]

You don't have to use theirs...

Who said that it was ELV?

How 'successful' (in the broadest sense - I don't doubt that dimming can be achieved), or 'desirable', is the dimming of halogen lamps? My understanding was that a high envelope temperature had to be maintained in order for the halogen to 'do its thing', and one imagines that dimming is likely to reduce that temperature. Does this impact on performance, efficiency and/or lamp life, I wonder?

Kind Regards, John

 

[westie101]

Found this: -

The need to de-rate a dimmer
When using Mains Voltage Halogen lamps such as GU9, GU10, GZ10 and Linear halogen lamps, dimmers should be de-rated by 25%.

This helps compensate for the additional load due to arcing at the end of the lamp life cycle. This extra load can damage the dimmer. Where possible it is better to use branded lamps such as those produced by GE, Osram, Philips and Sylvania. Generally these have an in-built thermal link and, should the lamp filament short out, the thermal fuse stops the inrush of current which can damage a dimmer. (LIF Technical Statement No.25). Many cheaper imported lamps do not have this thermal link.

here: - http://www.thelightbulbshop.co.uk/GuidetoDimming.htm

 

[333rocky333]

How 'successful ... I wonder?

Kind Regards, John

Not to digress on the ops post, but me and i beleive RF lighting have succesfully dimmed 12 volt halogens in pubs as well as our homes and i dont recall changing 1 failed lamp and Rf's had a low failure rate.

Ban is spot on, match the transformer to the dimmer and usually trouble free.
I beleive most next lights use toroidal transformers so it may need an inductive dimmer and may be soon followed by a why does my Mcb trip post

 

[JohnW2]

Not to digress on the ops post, but me and i beleive RF lighting have succesfully dimmed 12 volt halogens in pubs as well as our homes and i dont recall changing 1 failed lamp and Rf's had a low failure rate.

I wasn't really digressing. I thought that if people felt that dimming halogens wasn't too good an idea, it would have been worth bringing that to the OP's attention. In terms of your and RF's expereinces, I would note that we haven't actually been told that these are ELV halogens.

Ban is spot on, match the transformer to the dimmer and usually trouble free.

Again, although it may well be what the OP is looking at, no-one but BAS has actually mentioned ELV or 'transformers'.

Do you have similar good experiences with dimming 230V halogens?

Kind Regards, John

 

[AndyJay]

I'm completely lost with the replies!
Please, in layman's terms.

 

[333rocky333]

Next tend to opt for either halogen candles and state can use a standard dimmer
or
G4 capsules and state use a next dimmer, they tended to be Torroidal but i beleive some now use the cheap chinese electronic round ones

what the next dimmer is i dont know as ive never tried dimming a next light.

Sorry John im a 12 volt supporter and avoid the other stuff but a lot of our pubs use halogen candles and GU10, we get a few blown fuses and triacs but no worse than when tungsten and the managers dont really complain about lamp life

 

[333rocky333]

You need the details of the NEXT dimmer and match it.
However they may not be happy if you damage the light with an incompatible dimmer but cant complain if you use theres

A good start would be the part number of the light if its on there website so we know the lamp type

 

[JohnW2]

I'm completely lost with the replies! Please, in layman's terms.

Probably the important question in whether the light you've seen is using mains voltage (230V) halogen lamps or (extra) low voltage (12V) ones. Did you notice? If not, do you have a name/number of the light in question which might enable us to identify it?

Kind Regards, John

 

[ban-all-sheds]

I see no mention of transformers in the OP, just halogen lighting.

Ah....

 

[bernardgreen]

and no mention that running halogen lamps dimmed can shorten the time before the inside of the lamp blackens.

When the lamp is not run at full brightness the glass is not as hot as it should be and as a result tungstan vapour from the filament can condense on the glass and not be re-cycled by the halogen gas . The result is darkened glass and eventually the filament fails.

 

[JohnW2]

and no mention that running halogen lamps dimmed can shorten the time before the inside of the lamp blackens. ... When the lamp is not run at full brightness the glass is not as hot as it should be and as a result tungstan vapour from the filament can condense on the glass and not be re-cycled by the halogen gas . The result is darkened glass and eventually the filament fails.

Well, I sort-of mentioned it:

My understanding was that a high envelope temperature had to be maintained in order for the halogen to 'do its thing', and one imagines that dimming is likely to reduce that temperature. Does this impact on performance, efficiency and/or lamp life, I wonder?

Kind Regards, John

 

[ban-all-sheds]

Generally these have an in-built thermal link and, should the lamp filament short out, the thermal fuse stops the inrush of current which can damage a dimmer.

That's pretty much on a par, accuracy-wise, as claims that the rhythm method and withdrawal will prevent conception.