Door bell

[littlewil]

hi, looking for some advice please, i have found that my door bell is wired to the downstairs lighting ring and it causes the rcb to hum/buzz and when i disconnect the live wire for the door bell transformer it stops. So can i just install a new door bell transformer to fix the problem?

cheers in advance

 

[ericmark]

Not sure what a rcb is? MCB, RCD, RCBO clearly some typo error, but can't see why an isolating transformer would cause a RCD to hum/buzz, it would seem there is a fault, but one would need to test to see what fault and only then would you know if changing it would cure the problem, but for the price of a bell transformer if you have no test equipment it does seem a sensible thing to replace it.

 

[littlewil]

sorry i meant rcbo, the bell transformer is wired to the downstairs lighting ring rcbo in the consumer unit and makes a humming type sounds hen connected! when i disconnect the live going from the bell transformer to the rcbo the noise stops, so i was thinking maybe the bell transformer is defective?

 

[fluorescence]

It'll be a wire wound transformer which always hum a little bit. If it's got louder then it may be defective & best to replace it.

 

[littlewil]

brilliant thanks for that you can only really hear it when it’s quiet at night but it’s loud enough to hear and i have rubbish hearing!! can i just replace with any bell transformer from somewhere like screwfix?

 

[winston1]

Lighting circuits are NOT wired in rings.

A new transformer will most likely hum as well. Any bell transformer will not do, it needs to be the same voltage output. Rather than wasting money on a new one I would try mounting the existing one on rubber mountings. Maybe a grommet on each mounting screw so that the transformer is not toughing the wall or whatever it is mounted on.

 

[chivers67]

It's the RCBO making the Hum from my understanding caused by the Transformer being connected though.

 

[littlewil]

so this is what i have, and with the bell transformer wired into the rcbo (with the red marking) it makes the hummming noise which you can hear more at night when everthing is quite, and in the day you have to have your head near the consumer unit, if i disconnect it stops, i hope this help a bit more?

 

[AndyPRK]

Transformers do that.

If it’s quite hot replace it.

If you think its the Rcbo you could move the wires to another rcbo marked 6
To prove it isn’t

 

[littlewil]

Transformers do that.

If it’s quite hot replace it.

If you think its the Rcbo you could move the wires to another rcbo marked 6
To prove it isn’t

i’m pretty confident it’s not the rcbo, because without the bell transformer connected there is no hum! do you mean the bell transformer being hot? as to the touch it’s not hot at all! just makes the noise but i wouldn’t say it’s really loud i just noticed it the other night when everyone was asleep.

 

[DetlefSchmitz]

i’m pretty confident it’s not the rcbo, because without the bell transformer connected there is no hum!

Sorry, but that is illogical. Try AndyPRK's test or you may be throwing money away.

 

[littlewil]

but surely if it was the rcbo it would still make the same noise without the bell transformer connected?

 

[Deebeemoons]

Hi, I have this exact same problem, did you ever get this resolved. I've lived in my flat for 15 years and only noticed it in the last couple of weeks. One of the MCB switches powers the Lights, doorbell and MEV-M. I've have the MEV-M checked and that is fine I've also had an electrician out who said it was the bell transformer and subsequently replaced it. However the humming persists and is driving me mad, to the point I'm switching the MCB off at night as it's the only way I can sleep. Is the bell transformer for the door bell? if so would disabling the door bell completely and presumably this would allow the transformer to be removed a solution? Appreciate my door bell wouldn't work but I don't mind that.? If so is that an easy cheap job for an electrician and would it solve this constant humming. Thanks in advance for any help.

 

[winston1]

A new transformer will most likely hum as well as you have found out. I would try mounting it on rubber mountings. Maybe a grommet on each mounting screw so that the transformer is not toughing the wall or whatever it is mounted on.

 

[Deebeemoons]

Thanks for reply much appreciated. Sorry to ask more but I think the electrician tried everything he could and I've lived here for 15 years and it's only recently started humming, no idea why. The circuit box is in my bedroom so it's a right pain. Is the bell transformer just for the door bell? And could it be removed and the door bell disconnected from the circuit box, is this an easy job and likely to stop the humming noise? I don't care about the door bell as it's never used as we have separate video intercom in the apartment block. Guess I'll have to carry on turning off that circuit each night otherwise, I'm afraid its one of those things where once you've heard it you can always hear it. Many Thanks