On 19/10/2019 14:26, David wrote:
Looking for a multi-light fitting.
4 spot lights on a bar.

Screwfix designates most as "non-dimmable" but doesn't include the GU10
bulbs.
Separately it lists dimmable GU10 bulbs.

So what have they done to the light fitting to make it non-dimmable?

Quartz halogens may be dimmable but the recycling mechanism that keeps
the internal glass surface clean doesn't work if they are run too cool.
There may be dimmed settings where their working life is compromised.

Put another way they never regain full brightness when you want it.

If they are LED based then some are indeed not dimmable or could even by
damaged by attempts to dim them. LED fittings sometimes present too
little load for old school dimmers to work at all.

--
Regards,
Martin Brown