I've installed a battery operated door bell. I've checked that I
didn't nail a clip into existing cables so why does the door bell ring
when I switch on the kitchen light?
The kitchen light (flourescent) has always hummed and buzzed but
someone here said that was probably the choke?
So, why does my doorbell ring?
what route does the flex take from the bell push to the bell unit? If it is
in close proximity to the light it could be that on start up the light is
inducing a current into the flex and causing the bell to ring.
If it is a good, old-fashioned, "mechanical" doorbell with a striker and
either a couple of plates (ding-dong) or a dome (ding, ding ding ding):
Then there is no way it should be ringing. It must have some form of
electrical connection to the house mains wiring and you do need an
electrician to sort it out.
If it is a new-fangled "electronic" doorbell with a loudspeaker:
Then it is possible that the wires going to the bell button are acting
as an aerial and pick up "signals", such as electrical switching. The
earliest radio transmitters consisted of a switch and a coil - very much
like the starter and the choke in a fluorescent light fitting. Even more
so if the fitting isn't earthed.
So, as Dave suggested, it could be that the bell wires are running close
to some of the light wiring. Now most house wiring runs the supply wire
and the return wire in the same cable - which greatly cuts down the
"signals" it can radiate. The exception is light switch wiring, which
normally takes a supply wire down and a supply wire back, in the same
cable. So, running an "aerial" close to that cable can pick up stuff.
What to do?
I would suggest switching off the power at the consumer unit and then
have a look at the electrical connections to the light fitting and make
sure it has an earth connection (it could be a double-insulated one that
doesn't need an earth but they are very rare, IMLE). Fixing the earth
problem, if there is one, will typically much reduce the electrical
noise produced by the fitting and may stop the bell ringing.
Fixing the earth problem, if there is one, will much reduce the
possibility of an electric shock - say if you buzzing choke does
have/get a fault such as the fitting goes live. Next time you clean the
thing with damp hands, standing on metal steps.. yow. So worth fixing.
Failing that, maybe it is time to replace that old light fitting, anyway?
Or, if you want to keep the bell and the existing light fitting and it
has a good earth and you don't want to rerun wiring:
Go to Maplins or equivalent and buy a 1uF 25v (or higher)
non-electrolytic capacitor and connect it between the two wires going to
the bell push - but at the bell box end. What this will do is remove
most of any "signals" that may be picked up by the wiring. The bell push
will still work (the bell may keep still ringing for a fraction of a
second, or even a second or two, after the bell push is released,
though). This will work in many cases, but I can't promise it will work
The only thing I could add to that is there should be a suppression
capacator on the flourescent light. If that is faulty or not properly
connected it may cause a problem.
The first thing to do IMHO is to check that the lighting cable carries an
Many thanks for the advice. I'd suspected some sort of dodgy wiring.
I've re-routed the bell (a new electromagnet type) wire and found the
bell rang of its own accord with an open circuit. I took out the
batteries and re-inserted after 10 minutes, now the bell rings as its
supposed to when the bellpush is pressed - the only thing touched were
the batteries. Wierd.
This capacitor would stop all of that would it? I assume you meant
connect it as close to the actual bell as possilb? Again thanks to
both of you for the advice.
There is no way that a purely non-electronic bell circuit should pick up
enough induced energy from mains wiring to ring the bell. Wierd doesn't
describe it. Electromagnets work on current. Whilst you might induce a
high enough voltage in a wire to trigger a semiconductor device, you
aren't going to induce enough current to energise a solenoid. In fact,
you have no current, with the bell push switch open, no current can flow.
A capacitor would help with an electronic bell, as the capacitor acts
like a short circuit to any transient voltages travelling up the bell
wire, and stops these voltages triggering the bell electronics. It is
put as close to the electronics as possible - to stop any possibility of
voltages being induced in the wire between capacitor and electronics.
It isn't going to make any significant difference to a pure
electromagnetic bell at all. It won't do any harm though.
I'd be having a closer look at the bell - the only realistic way the
bell could operate off electrical noise with an open circuit is if they
have put a bit of electronics in for some reason - eg to reduce the
current in the bell push to make it last longer, to commutate the coil
(eg repeatedly ding-dong whilst the button is pressed, rather than one
ding and one dong etc.
Is this a wind up?
Did the last doorbell ring?
Take the starter choke out of the flourecent light and try the switch
again? obviously the light won't come on but we're doing a test,if nothing
then change the starter choke for elimination purposes.
It isn't by any chance a wireless doorbell?
| I've installed a battery operated door bell. I've checked that I
| didn't nail a clip into existing cables so why does the door bell ring
| when I switch on the kitchen light?
| The kitchen light (flourescent) has always hummed and buzzed but
| someone here said that was probably the choke?
| So, why does my doorbell ring?
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