Wiring Hum - what could cause this?

[Hrossey]

I have a 10 year old timber framed house which is a self-build (not by me).

There is a loud humming sound from behind the wall in my daughters bedroom. Have tracked this to the electrical circuit which feeds the hallway and the sitting room lights. Sitting room is directly below her room. Found out which circuit the hum was on by removing fuses from the fuse box and listening.

Any ideas what could be causing the hum and how to solve it. The noise is the same whether or not the lights are on and is constant - and VERY annoying.

D

 

[Spark123]

Doesn't back onto the bathroom does it? Shaver socket?

 

[RF Lighting]

Burglar alarm maybe?

It will most likely be someting that incorperates a transformer (causing the hum), and stays on all the time (constant hum).

 

[securespark]

Before you start demolishing walls, you need to try & isolate it to a specific piece of equipment.

It most likely is transmitted noise.

 

[Hrossey]

Well it doesn't back onto a bathroom so it's not a shaver socket and we don't have a burgler alarm. The wall the hum comes from is an outside wall and we initially thought it might be coming from the TV ariel booster as it is near that bedroom. However, tracing the sound to the sitting room/hallway lighting circuit probably rules that one out.

I did wonder about a transformer but my husband doesn't think there is one anywhere in that neck of the woods.

Sorry to sound a bit thick, but what would be likely to cause a transmitted sound? The hum is quite "directional" ie if I sit with my back to it it's not so loud but if I turn me head it's much much more noticeable, more so than with most sounds.

D

 

[securespark]

Well, transmitted noise can happen for example if you have a fan unit in the loft fixed to the joists, and the hum/vibration is transmitted down the timber to other areas.

So the outside wall the noise is coming from is hollow? IE timber frame in middle, brick on outside and plasterboard on inside and filled with rockwool battens?

I would go to where the noise is strongest and try to find the source. Can you feel it if you put your palms on the wall?

Have you got T & G or chipboard upstairs? If T & G, would it help to lift a board to try & locate the source?

 

[SparkyMarky]

Could it be a bell transformer for your doorbell? it's feasible that this is fed from a ground floor lighting circuit if the bellbox is mounted near the ceiling in your hallway. Try removing the fuse and see if the doorbell still rings...