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Hi,

I have a heated and LED lighted bathroom mirror with integral shaver point, however the shaver transformer buzzes.

The LED and Heat pad are controlled via an IR sensor switch. On the switch control box inside the mirror it says:

100-240VAC
Max Lighting Load: 250W
Rated Current: 1A

My question is, can I alter the wiring inside the mirror (which I'm fine doing) so that the Shaving Transformer comes on with the LED lights and Heat pad via the IR switch as opposed to it currently being on permanently? I have disconnected the live feed to the Shaver Transformer for the time being as the buzzing noise is annoying given the bathroom is an en-suite.

Interesting set up. Why the wago and why so many earths?

Hi, no ideas on the earths. I put the wago in as I disconnected the live from the shaver transformer which was in a 3 way crimp connector wrapped in heat shrink. I just used the wago to reconnect the other 2 wires temporarily as I will just replace with a single length of wire.

Is there not a switch inside the cabinet?

Theres an ir switch hence my query as to whether I can rewire the shaver transformer to work from this given the switches limits on amperage?

I would guess the answer to your question of "can I alter the wiring inside the mirror so that the Shaving Transformer comes on with the LED lights and Heat pad via the IR switch" is no.
It is not the current I am thinking of that is the main problem, it is the fact you want to switch a transformer. Transformers are an inductive load, when you switch them off you get what is called back emf. In plain English back emf is a high voltage, that has the ability to cook things. You may be lucky and "get away with it for a while" but I wouldn't try.

You could try putting "rubber" under the transformer to reduce the noise.

kevkdg wrote: ↑Wed Jul 28, 2021 7:10 pm Theres an ir switch hence my query as to whether I can rewire the shaver transformer to work from this given the switches limits on amperage?

I said inside the cabinet. Our cabinets have switched in them ….

Someone-Else wrote: ↑Wed Jul 28, 2021 8:33 pm I would guess the answer to your question of "can I alter the wiring inside the mirror so that the Shaving Transformer comes on with the LED lights and Heat pad via the IR switch" is no.
It is not the current I am thinking of that is the main problem, it is the fact you want to switch a transformer. Transformers are an inductive load, when you switch them off you get what is called back emf. In plain English back emf is a high voltage, that has the ability to cook things. You may be lucky and "get away with it for a while" but I wouldn't try.

You could try putting "rubber" under the transformer to reduce the noise.

Thanks, hadn't considered this, but would this also not be true of the LED transformer which is already switched?

The device powering the LEDs is a "Power supply" (As it clearly says) it does not have a true transformer, so is not an inductive load.

Someone-Else wrote: ↑Wed Jul 28, 2021 10:35 pm The device powering the LEDs is a "Power supply" (As it clearly says) it does not have a true transformer, so is not an inductive load.

I thought the LED power supply was a step down transformer. The input Pri is 220'240vac but output on Sec is 3-9vdc

Someone-Else wrote: ↑Wed Jul 28, 2021 8:33 pm I would guess the answer to your question of "can I alter the wiring inside the mirror so that the Shaving Transformer comes on with the LED lights and Heat pad via the IR switch" is no.
It is not the current I am thinking of that is the main problem, it is the fact you want to switch a transformer. Transformers are an inductive load, when you switch them off you get what is called back emf. In plain English back emf is a high voltage, that has the ability to cook things. You may be lucky and "get away with it for a while" but I wouldn't try.

You could try putting "rubber" under the transformer to reduce the noise.

Apologies, another query on back EMF.... A lot of wall mounted Shaver units have an integral switch activated by the two pin plug, or on some mirrors an IP44 rated cabinet rocker switch.... would the back emf also be an issue in these instances, or is it simply the fact that it might affect the electrics in the IR Switch unit?

Please stop quoting the whole reply in your post, it is annoying and a waste of time, and can be confusing.


Humour me.

Look at your mobile phone charger, is it big? now look at a laptop charger is it big? The answer is obviously no, they are small. How do you suppose they get a transformer inside said devices? the answer is they don't, there is no transformer, but yet you send 230v ac in (You plug it into the mains) and 12v dc comes out how does that happen? In short it is done with electronics (Capacitive dropper*)

A transformer is made from a multi layered iron core with two coils of wire wound round said core. This usually makes them large and somewhat cumbersome, as you show in your picture, the transformer is the biggest item. The iron and the wire and the time taken to make a transformer are expensive compared to the cost of a few components.

I believe you will find most shaver sockets don't have an internal switch (Pointless and adds to the cost) shaver sockets are on 24/7 and use negligible current and sometimes you do find people asking how to stop the shaver socket from humming even though they are not using it.

Back EMF is only created when you switch the primary side of a coil off. It is a very high voltage (It is also what makes "old" cars run as it is how the spark is generated for spark plugs, the spark is generated when the coil is switched off by the "points", and since the points open and close a lot, you get a continuous spark)

This high voltage can "cook" components that are not designed to handle such high voltage, which brings me back to where I started.

*Capacitive droppers are not an inductive load.

Many thanks @Someone-Else

Someone-Else wrote: ↑Thu Jul 29, 2021 10:22 am I believe you will find most shaver sockets don't have an internal switch (Pointless and adds to the cost) shaver sockets are on 24/7 and use negligible current and sometimes you do find people asking how to stop the shaver socket from humming even though they are not using it.

Ah, no worries, just read somewhere that MK ones (I think) were activated by plugging in the shaver etc, but probably have misread.

So, in summary, any type of switch will be bad on the transformer due to Back EMF, even an IP44 rocker switch such as the following, or is it simply that my query was around utilising the IR switch which maybe more sensitive etc?:

https://www.bathroomspareparts.co.uk/hi ... 0883-p.asp

Out of interest, when I switch off the isolating switch to the en-suite lighting circuit that also powers the mirror, what happens then as I assume Back EMF is generated each time?

I can't put up with the buzzing/humming noise which is probably amplified due to the Transformer being in a cabinet. There is a foam padded piece between the Transformer and the cabinet surface, but I think the sound is simply amplified anyway. As things stand I have simply disconnected the Live feed to the Transformer (the neutral is still connected). I suppose I'll just have to leave it disconnected :-(

Neelix wrote: ↑Wed Jul 28, 2021 6:27 pm Interesting set up. Why the wago and why so many earths?

Supplementary bonding as per the 16th edition. On the top earth cable you can clearly see it it labelled up as 4mm and the stranded cable with the copper showing entering the bottom of the strip connector is also 4mm.

kevkdg wrote: ↑Thu Jul 29, 2021 10:42 am So, in summary, any type of switch will be bad on the transformer due to Back EMF, even an IP44 rocker switch such as the following, or is it simply that my query was around utilising the IR switch which maybe more sensitive etc?:

It's the IR switch that may burn out. A rocker switch will be fine.