Doorbell transformer

[ajsdoc]

I'm replacing my doorbell as we are redecorating.

I'm moving the doorbell elsewhere also so it means running new wires.

Anyway it's a transformer wired outside the fuse box.

I got my multimeter out and when reading across the "8V" tapping I get 19V with the multimeter set to its lowest AC volt setting. If I connect the bell wire it's the same (obviously I suppose).

Is this within normal limits or is it a sign the transformer needs replacing. If so is this something I can do? (It looks straightforward, the bell is on its own MCB on the board and is isolated when this is turned off, confirmed by meter). All help appreciated, the bell works fine when connected by the way, don't know why I tested with the meter (just curious...)

Thanks.

 

[Lectrician]

What does the meter show when measuring the input?

 

[ajsdoc]

Thank you.

Now I'm really surprised, 296V !!

Does this point to a possible problem with my multimeter? I've had it a good few years. Should I buy another and test again?

All help really appreciated.

 

[Lectrician]

Change your batteries first

 

[ajsdoc]

Thanks!

Feel a bit of an idiot!

In the meantime popped out and borrowed a mate's multimeter!

Input voltage reading now a respectable 246V

Output voltages now lower but still high - 16V across 8V tapping and 10V across 6V tapping.

New one needed or within bounds of reasonable? Not sure how sensitive cheaper multimeters are at lower voltages?

They don't seem expensive if I need to change.

Should I or should I just crack on and stop testing things!

 

[AndyPRK]

Input voltage reading now a respectable 246V

Oh not 230V then Don't tell winston!



The output voltages of bell transformers do tend to be high.
May drop when the bell rings (on load)

 

[333rocky333]

should I just crack on and stop testing things!

Yes

The bell may be glad of the extra volts ( if there is ) as many bell problems are issues with volt drop at the actual bell.

May be worth measuring at the bell whilst its operating on the end of the installed cable, the voltage will be lower

Test your meter on a battery of known voltage, ie 1.5 volt or similar

 

[ajsdoc]

Thank you all.

I'll crack on and stop faffing.

Seems my equipment doesn't work as well as it did and is less reliable than it was. My wife has mentioned this in the past.

 

[OwainDIYer]

try measuring the voltage with the bell sounding.

The transformers are unregulated and voltage will rise when no load.

 

[winston1]

Input voltage reading now a respectable 246V

Oh not 230V then Don't tell winston

No need to. I already know UK mains is not, never has been, and is not intended to be 230v.

 

[RF Lighting]

Yes it is. The op has a supply within +10% of 230V.

You need to accept that things have changed, and stop proving to everyone here how ignorant you are.

 

[winston1]

Yes it is. The op has a supply within +10% of 230V.

You need to accept that things have changed, and stop proving to everyone here how ignorant you are.

He also has a supply within +100% of 127V.

Nothing has changed apart from the stated figures and tolerances. Stop being an idiot and pretending the UK voltage has gone down. It has not and there is no intention of doing so.

 

[EFLImpudence]

Can the moderators please remove winston's pointless and illogical ramblings whenever they occur in order to remove the need to swear and abuse him.

 

[RF Lighting]

Yes it is. The op has a supply within +10% of 230V.

You need to accept that things have changed, and stop proving to everyone here how ignorant you are.

He also has a supply within +100% of 127V.

Nothing has changed apart from the stated figures and tolerances. Stop being an idiot and pretending the UK voltage has gone down. It has not and there is no intention of doing so.

But +100% of 127V is not a recognised supply voltage.

What do you think the UK supply voltage is?

 

[winston1]

Whenever I have measured it over the last 50 years it has been around 242v. I have never seen it below 237 or above 245V. I therefore think it is around 240V, certainly not 230V.