On 01/08/2018 13:28, Dave Plowman (News) wrote:
In article 2,
DerbyBorn wrote:
I have just had a touch dimmer fail.

I had used it to control a bar with 4 x 50 watt GU10s.

I replaced with LEDs and ov course it wouldn't work as it had a 40watt
minimum load requirement.

I put a Halogen back in and it worked - but after a while the dimmer
failed. Could this be due to it seeing a mixed load?

Were the LEDs officially capable of being dimmed?

I have now replaced the dimmer with one that says 4 watt LED min.

Dimmable LEDs usually need a trailing edge dimmer. Depending on design,
long before LEDs arrived, some were but most weren't. I've got MK grid
dimmers in one room fitted in the late 80s, and they are fine with LEDs.
But other much newer ones which had to be changed.

So saying, I'm not sure why a LED would cause the dimmer to fail. Where
I've mixed tungsten and LED with an 'old' dimmer, the LED just failed to
dim.

It fails to dim by drawing progressively more current during the
shortened on part of the mains cycle until the semiconductor maximum
peak current gets exceeded. Even some dimmers that are supposed to be OK
with dimmable LEDs seem to suffer unexpected failures in service.

I know someone who has had several fail inside the warrantee period
replaced with identical ones from a later batch that also failed.

--
Regards,
Martin Brown