Wiring doorbell transformer to mains plug

12 Dec 2020
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United Kingdom
Hey folks,

I bought a wired doorbell from screw fix. This one specifically https://www.screwfix.com/p/byron-72...-rwNM7anRzlwh_etILhoC6yIQAvD_BwE&gclsrc=aw.ds

So here comes the silly question if you nice folks can help me please. In the Q and A section on the site it says it man be wired into a mains plug. I've done that but there is nowhere to connect the earth wire to on the transformer from the power cable.

Tell me I'm doing something wrong.




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Thank you sparkymarka. So should I just tape off the spare earth or should I have bought a cable without earth?

I guess what I'm asking is can I plug it in without going bang.
Tell me I'm doing something wrong.
Your power supply is a class II appliance, it does not require an earth connection.

You only need to use a two core cable.
You could use a three core cable, but the earth wire would need to be safely isolated, in a way that it can't touch either of the other terminals.

However, the cable you are using appears to be overly large, a smaller cable would be easier to connect. You also need to shorten the length of the exposed inner cores; when you put the cover/cord grip back on, there should be no exposed cores showing.
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Thank you randomgrinch. In my haste I picked the first 1 meter cable and it's a 2.5mm one and overly large like you say. I will get a thinner 2 core and do it in the correct manner tomorrow.
I don't want batteries, always have problems with wireless and have no existing wires to use. I appreciate it could be placed in a consumer unit by an electrician but other than that I thought I would need to plug it in as a DIY job.

I'm here to learn so if I missed another way of doing it I'm all ears and willing to ask stupid questions
Personnally I'm not a big fan of those bell transformers with the small covers secured by a quaerter turn plastic fastioner, and certainly not keen on them if supplied by a flex and plugtop as there isn't really any proper strain relief. I'd personally install in a plastic adapatble box with a stuffing gland for the flex.

I've seen an 'electrician' replace a failed one of those transformers with the terminal covers with a different one that just had the terminals exposed as it was only intended to be installed inside an enclosure, the fact that unsheathed cores could be seen from the otherside of the room and the 240v terminals were accessible on the outside didn't seem to hint that there was something not quite right about the job....

The older transformers with the covers secured by proper screws were a lot better https://securitytradesupplies.com/wp-content/uploads/2020/07/friedland752.jpg
The transformer show is designed to be fixed, and the cable cleats use will stop anything snagging on the cable and pulling it out, if free standing then some cable clamp would be required inside the unit.

I have gone half way, my door push 1700300086220.png is battery powered, and my sounders 1700300210685.pngwhich are also hubs, plug in, I had not intended to do that when I bought them, the button was so dining room lights could be turned on/off from the temporary bed when wife had knee done. But once that was no longer required the two TP-Link hubs one Tapo the other Kasa were linked to the push button, and button reused as a door bell push button. It also logs every time pushed, but on the minus side is not totally water proof, however our door is reasonably protected from direct rain. Big advantage is two sounders from one push button.

But nearly every other door bell we have had has been the same, push button battery powered, but door bell mains powered. Many years ago we did have a hard wired system, but water got into the door push, so having hard wired did not really help.

The problem we have is people not pressing the door push, they say we called but no one answered, the reply now is when, at which we look on the log, and say well no one pushed the door bell at that time, so that is clearly why we did not answer the door. We did not do it for that function, but now we have it very handy.
Thanks for all your help folks. I got a two core wire and have successfully cabled it all together, cabl clipped all cables to the wall and mount the unit, transformer and bell.

It was for a relative and they are happy they have a good old fashioned ding dong.

I need to do similar at home, but it was a ballache for me so I will investigate some of the other options up thread.

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