Electrical hum noise from shower fan electrics box

Question

I had a shower fan installed about 8 months ago, a vent axia low carbon with timer on light switch. The separate small plastic box that contains all the wiring separate to the fan makes an electrical humming / buzzing sound, my electrician has said he can't hear it and didn't seem very concerned, he's very good and reliable normally.

But it's very audible in the silence of the bathroom when nothing else is on, it doesn't to buzz when the plastic front casing of the box wasn't fixed on and the wires were loose, it was like this for several weeks whilst wiring and partition ceiling was being finished. Surely the wires simply being pushed a little tighter into the box to fix on the front and close it shouldn't make it hum and buzz? What could this mean? Is it dangerous?

Answer 1

Electrical hum like that can be a symptom of a loose connection in the wiring. It's possible that something came loose when the wires were pushed up into the junction box. If so, the worst case would be an electrical fire, so it's definitely something to have looked at. Less terribly, you could lose power to the fan, where you'd probably have the electrician out again anyway.

If you're comfortable looking into it yourself, turn off power to that circuit at the service panel, open the cover and look at each of the connections. Your profile doesn't say where you are, but in the US, wires are usually connected using electrical nuts. Tug gently on each wire going into the nut -- there shouldn't be any give. If there is, remove the nut, arrange the wires so that they're parallel, use a pliers to twist them together, then screw the nut back on. People often wrap electrical tape around the open end of the nut, but it isn't required.