I wrote to the group a while ago about brands of dimmer switches and
have now opted for an MK single plate 2 gang dimmer. It controls standard
wall lights on one switch and mains halogen ceiling lights on the other.
Unfortunately I could not find the cheap MK model that doesn't cope with LV
halogen and had to go for the all singing all dancing model. Anyway, when I
turn on and dim the wall lights (bog standard bulbs) there is no problem.
However, when I turn on the mains halogens there is a buzzing noise coming
from the switch + the lights themselves (I think it's also coming from the
lights but I could be imagining this). I am used to LV halogen transformers
buzzing as they did in the kitchen of my previous house but I did not expect
mains halogens + dimmer switch to buzz. Is this because I've got an
unnecessary transformer in the equation or am I stuck with it ? Can I buy a
dimmer that will only cope with mains voltages and the buzzing will go away
Thanks for any help you can give,
I'm a complete arse when it comes to knowing anything about
electrics so I unfortunately can't answer any of your questions. These were
fitted in my new build property and I don't even know what type of halogen
bulbs they are or what the fitting is like - the electrician just mentioned
that they were mains voltage on one of his many visits to fix stuff. I
haven't had a need to change a bulb yet. I'm also so concerned about the
quality of the fittings themselves that I don't want to go removing bulbs
unless it absolutely necessary. I've already had the bathroom halogen
fittings start falling out of the ceiling :-(
As such I thought that they didn't need a transformer as they have been
called 'mains voltage' but I am probably wrong. To install the dimmer I
simply copied the wiring from the original 2 gang switch into the dimmer
thinking it was as easy as that. Unfortunately I can't even recall if they
buzzed before but I'm pretty sure that they didn't.
Apologies for being a bit dim .... gettit :-) Sorry.
I've got mains halogen wall lights on a dimmer, and the dimmer buzzes
quietly - I've not met one that didn't (ducks incoming), and the lights
often sing quietly.
When I asked for advice the gist seemed to be "get used to it"
Maybe thinga are better now, but - you are not alone
That is good to know in a weird kind of way :-) I'm not bothered if
I can't improve it 'cos the benefit of dimming the spots far outweighs the
slight buzzing. I've got a pet cockatiel that stayed awake (and sang at the
TV) until the lights were turned off completely. Now we can dim them he
seems far more laid back and quietly drifts off to sleep with the lights
dimmed thank goodness.
I haven't got a cockatiel, I just like watching old films last thing at
night with the lights down low and a couple of tins - I don't know why the
lights sing, but they do! and I get a much lower dim than using floor lamps
"If we hook up a really cheap dimmer switch, we may notice a
strange buzzing noise. This comes from vibrations in the bulb
filament caused by the chopped-up current coming from the
triac (triode alternating current switch)."
"Better dimmer switches have extra components to squelch the
buzzing effect. Typically, the dimmer circuit includes an inductor
choke, a length of wire wrapped around an iron core, and an
additional interference capacitor. Both devices can temporarily
store electrical charge and release it later. This "extra current"
works to smooth out the sharp voltage jumps caused by the
triac-switching to reduce buzzing and radio interference."
In my experience it often the choke in the dimmer that buzzes esp. in the
Potting the choke in silicone or epoxy can alleviate this.
I believe halogen bulbs buzz more than others because they can respond to
the chopping action of the triac.
Can you tell me if the fitting is deep, as in, about one and half inches
(40mm) deep. If it is any thinner than this, then it more likely to have
240Vac halogen lamps in it.
I'm afraid that I don't know... the bathroom fittings didn't make it all
the way out of the ceiling before they got pushed back in. I'll have a
check of one of the bulbs over the weekend if I get the chance.
Ah Ha !!! They're recessed lights ? Small fittings ? With small lamps
inside them ? Fitted to a transformer ? If they are, then check that the
transformer is really a dimmible type. The fact you say that both the
dimmer and the lights are buzzing is getting to me. I've heard dimmers
switches buzz, but not the lights as well.
Mine do, BW. An earlier answer makes me think I might look for a better
dimmer, and it's some time since I looked, but my definitely mains halogens
do sing, at quite a high pitch,somewhere round F (4 above middle C)
Does anyone know how I would know a better dimmer if I met it?
Correction. You wouldn't.
However 'electronic' transformers are actually thungs that take the
mains, turn it into more or less high voltage DC, smoth it a bit, then
chop it rather fast to apply it to a little ferrite transformer. That
steps it down to 12vAC at a fairly high frequency. Its probably that
which is audible.
Use a toroidal.
AFAIK LV light units do not use DC, ever.
All dimmers buzz to some extent. If you take one apart you will find
one, or more, toroidally wound chokes inside. This is probably what is
doing the buzzing. As the nasty sharp edged dimmer currents go through
it the wires expand and contract in teh magnetic filed.
If you soak the windings in Epoxy that should help a bit.
The chokes stop the nasty edges getting into you radio, so don't short
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.