RE: CBUS dimmer & GU10 LED not functioning as expected

["Phil Harris" <phil@xxxxxxxxxxx>]

Unfortunately Chris in this case it's not...

...most low cost electronic dimmers do not isolate the outputs when they're
turned off. (And yes, the C-Bus DIN rail dimmers are low cost still.) What
this means is that with no load (or with a very high impedance load) the
outputs will drift up to 240v but at a very tiny current. Any
"normal" load
(a bulb or a transformer) will drag that down to 0v (hence why it works if
you put a bulb in parallel).

In the case of the C-Bus dimmers it is *NOT* that they use the load as a
neutral to allow the dimmers to work (as is the case with - for example -
an
X10 wall switch replacement dimmer).

GU10 Halogens and GU10 LED bulbs do not dim in the same way and the C-Bus
DIN rail dimmers (as with most other electronic dimmers) are not suitable
for driving LED fittings in that way.

Phil

> -----Original Message-----
> From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf
> Of Chris Hunter
> Sent: 02 September 2007 13:28
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] CBUS dimmer & GU10 LED not functioning as
> expected
>
> IIRC, this maybe something to do with a small current path being
> needed for the dimmer electronics to function ...
>
> Chris
>
>
> On 2 Sep 2007, at 13:23, Adrian wrote:
>
> > Have also found out if I plug a normal GU10 bulb in to one of the
> > sockets (theres 2 on each run) so theres a normal bulb and a LED
> > one it
> > works fine
> >
> >
> > Adrian wrote:
> >> Hi
> >>
> >> have a 240v GU10 LED wired to a CBUS dimmer channel and it
appears
> >> that
> >> when the channel is off, i read 50v on the cct (which causes
the LED
> >> bulb to glow at about 50%), if I unplug the bulb this drops
to 0.
> The
> >> LED is not a dimmable type and I had configured the channel
for
> >> instant
> >> on/off operation, is this normal for LED bulbs?
> >>
> >> Am going to cut across to a relay but i though this would of
worked
> >>
> >> and advice appreciated
> >>
> >> Adrian
> >>
> >>
> >
> >
> >
> >
> >
> >
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