Voltage Detector

[inquisitive]

Thanks all for your comments. A bit to digest!

 

[Telecoms_man]

If just removing the door contacts, the wires going to them will be a voltage of 12V and very low current, so no need to isolate the alarm panel and remove the battery. I doubt whether a GS38 voltage indicator would even register.

I assume the doorbell is mains voltage powered? Even then the door push button itself will be of a very low voltage, so again no need for isolation.

Or have I missed something as to why door contacts and a doorbell push need to be isolated?

 

[pc1966]

Certainly a doorbell ought to be safe low voltage and no real need for the above.

But the question started on voltage testers and if you are testing for the possibility, even if very small, that someone or something has left a circuit at a dangerous voltage you should always start from the assumption it is dangerous, until proven otherwise.

So you should really use test equipment that is safe for what might be present. Also for any other job in the future where you know it would normally be 230V, etc.