Dimmer & Low Voltage Nightmare

[Dafulang]

I have had a good look through earlier postings but I'm still not totally clear. We have a MK dimmer switch (2 gang one way) linked to standard ceiling lamp and wall lights. We recently bought a new ceiling lamp, 5 * 20W bulbs, but it is low voltage with a transformer enclosed in the metal part that fixes to the celing. The light's instructions state that this can't be dimmed. However, the chap in the local wholesaler's seems to know his stuff and suggested that simply bypassing the transformer in the lamp with a new dimmable low voltage transformer would be ok. This seemed fine and I was happy to do this until I looked at the instructions for my MK dimmer which states that it's not suitable for low voltage fitting. Returning to the wholesaler, he explained alot of incomprehensable technical reasonings but basically said that they were simply covering their backs and that it would work fine with no problems (nor dangers!). But, if I wanted to be 100% sure I could buy the level up MK Dimmer for £45 + VAT and throw the old £30 dimmer in the bin!

Can anyone advise if a standard (MK) dimmer would be ok to use with my new fitting provided that I connect the dimmable transformer or will I ALSO have to fork out for a new low voltage dimmer? If it is the latter, am I allowed to buy a cheaper low voltage dimmer and put these innards into the MK fitting (provided that they fit, obviously)?

Hoping someone can help, Dafulang

 

[Steve]

Bought a low voltage lamp from homebase a year or 2 ago, and its been on a dimmer since it was fitted, no problems, it doesn't even hum, like the one from Ikea did when it was on the same dimmer. Whether it is actually dimmable is another matter!!!! And the dimmer in question was a cheap £8 job from Wilko. . . . .

 

[baldelectrician]

mk dimmers come in various kinds

you need the dimmer with the suffix LV at the end of the catalouge number

You need to marry up the right type of dimmer with the right type of tranny.

 

[Rack]

The transformer originally in the light fitting, is that a big heavy one?
If it is, that it is a magnetic transformer, it uses a big magnet and coils of wires to transform the voltage down.

The potential problem with these sorts of transformers with dimmers, is that if the dimmer does something wrong and introduces a DC current (ie constant) into the AC power, then it can burn out the transformer, which is a fire hazard. A good dimmer shouldn't do that.

An Electronic LV transformer won't do that, but you really need a good trransformer and compatable dimmer which is made for those sort of transformers, otherwise you can get all sorts of problem from lots of noise on your mains line, from buzzing to interference with other items, to flickering lights or outright failure of the dimmer/transformer. It's not easy

 

[Dafulang]

Thanks for the advice. It sounds as though I'll have to fit the new electronic transformer and then see if I get away with keeping the original dimmer???????

 

[Dafulang]

I have now taken th eplunge and fitted the lamp with its existing transformer. The switch is still the regular dimmer I had before. When the light is turned on there is a loud humming from the lamp, not the dimmer. Is this caused by the dimmer switch? i.e. will it carry on even if I fit a LV dimmer switch? Hope someone out there can assist. Thanks.