Bell-push rating

The mud room which houses the rear door bell is being replaced, and as the old bell-push was intermittent, I decided to fix it. Success, cleaned and tested and ready for use.

But then I got thinking: Like all such bells, the step-down transformer is powered all the time, pointlessly using energy, and the button merely closes the low-voltage circuit. In the interest of not wasting power, it would make much more sense to switch the input mains power, so there is only power consumed when it is needed, maybe once every three months, in my case. Is the reason that it is done this way to keep only low-voltage power at the outside push-button? A weatherproof button should not be too difficult to make and install.

But trying to find a 240-volt rated push-button is proving difficult. Most online suppliers don't even mention the voltage rating, and it is only by reading the reviews that it is always revealed as low-voltage only. Maybe I need an industrial Allen-Bradley button! Back when I was working, I could have had as many of those as I wanted.

Most annoying.

The actual current drawn by a transformer when its not loaded is really quite small, and the better quality it is, the less it is, and its also largely reactive current, for which you should not pay.

Depending on how much the bell is used, you could get rid of the transformer and replace it with a couple of "C" or "D" cell batteries (or 4 batteries if it's 6V). They'll normally last years with little use. Whether or not they'll cost more than the electricity you'll save is something only you will be able to say. You'll require an AC milliammeter to measure the quiescent current usage of the transformer, and then calculate the total amount of kWh consumed by it in a year. Compare it over the same period with the assumed life of the batteries, and factor in the cost of the electricity and the cost of the batteries over the same period.

Or you might consider it's all too much of a faff and just leave the transformer doing its job!

Have you considered using a battery operated bell, like I have. If you don't get many rings, alkaline batteries last a few years.

the cost would take a while to amortise: e.g. if the no-load power is

The problem I found with a battery operated bell was that the only time anybody used it was after the batteries had died.

How did you know.?

They knocked.

I long ago realised that that is not a valid reason to not do something. The other job might still be hiding in ten years' time.

The bell fitting itself does in fact have a holder for 2 D Cells, but it sounds a lot better using the 12 volts of the transformer.

Use the batteries and push button to operate a relay that energises the transformer to power the bell with 12V :-)

Zap visitors

For good reason... running 240V on inadequately insulated and protected cable into an "outdoor" environment is really not a good idea IMHO.

If you are that worried, swap the transformer for a SMPSU - you probably have one sat in a drawer somewhere anyway :-)

How comfortable would you be pushing a "normal" but soaking wet bell button knowing that it was running at 240V?

I think I'll just re-assemble it as it was, after all that! Certainly the simplest solution.

"19mm 220V LED Metal Stainless Steel Switch Illuminated Pressure Switch Button IP65"

And if the stainless look is too obtrusive:

Else use a switching wall wart -- maybe find a phone charger from before-USB days at 12 Volts.

Thomas Prufer

Clearly no need for the bell.

Interesting, thanks.

Depends on where you are in the house or yard.

You are right in your assumption. It is for safety that they use the low voltage only side. You could of course make it a wireless one and join the