Bathroom Mirror Shaver Transformer Buzzing

[kevkdg]

I have a quick query. I have a bathroom mirror with built in shaver socket and isolating transformer. However, it is not switched and is permanently on and as it is in an en-suite the humming/buzzing noise of the transformer is amplified from within the mirror casing and is annoying. I am confident in re-wiring the isolating shaver transformer to the mirror's infra-red switch (currently used to turn on and off the LED lights and demister heat pad) BUT am not sure on whether this would be OK mainly due to "Back EMF" associated with transformers. Could this damage the IR switch? If Back EMF is a general issue, then how does the Shaver Socket you dismantled get around this as that had an on/off manual switch.

 

[telectrix]

1 solution would be to remount the shaver Tx with rubber washers.

 

[Lucien Nunes]

Buzzing can indicate a faulty transfomer, or one with loose parts. It could be as simple as the mounting screws being tightened in a position that allows the core to vibrate within the wraparound clamp. Or it might be that the flux leakage from what is a low-cost (albeit safety-enhanced) transformer unavoidably sets up vibration in the steel housing of the mirror.

The IR sensor unit appears to have a relay output (presumably makes a click when switching on or off) and it will probably be fine to switch the transformer. One spec page for that module appears to sanction use with transformers, although another states 'electronic transformers' which from the module's point of view are not really transformers. Sensors with triac output would not necessarily be suitable though.

Don't forget that altering the design of a commercial product can invalidate its safety and EMC approvals and transfer design responsibility to you.

 

[benawhile]

Old thread I know but I have the same problem and considered a similar solution but if you are effectively wiring the mains in a bathroom to a switch mounted on a metal cabinet which protrudes to the outside, wouldn't that contravene regs? In my case I would have been using the switch for the demister, which is originally connected to a low voltage circuit and I am even more sure that would contravene, even though it is in a watertight silicone rubber case.