Why wouldn't a volt pen pick up voltage?

[Petej999]

Well I'm confused !

Just went to isolate some kind of antique shower pump thingy in a bathroom for a plumber mate but the switch to it in the bathroom was painted over several times so I couldn't get my voltage tester with probes on it. So I used my non touch volt pen on the switch and the cable going into the switch which showed 230v power.

I isolated what I suspected was the power supply in the basement - an old wylex isolator. Tested the bathroom switch again with my volt pen and 0 volts - Fair enough. That would suggest the isolator was the right call.

Thing is though, When I tried my volt pen at the cable at the isolator (as a whole and also each individual conductor in the isolator) I got no voltage displaying on my pen - with the isolator energised or not. I checked the fuse in the isolator which is fine.
I retried my voltage pen on the switch in the bathroom with the isolator energised / not energised, with the same results.

SO, why am getting a reading with my voltage pen from the bathroom switch and cable at the bathroom switch, but not getting a reading at the isolator outgoing cable??

I'm going to have to return when I have more time to smash open the switch and do more substantial tests cos I like this plumber but I'm still at a loss on why this be...

View attachment 98641

The short answer is , don't use a volt stick/pen when testing for safe isolation purposes,

 

[captaincaveman]

UPDATE:
I went back, Isolated both at the Memspan switchfuse (thank you Lucien) and also at the main CCU (as an additional percaution), used my volt pen on the painted over switch in the bathroom, smashed the bloody thing open with my hammer, and did dead/live testing for real with my voltage tester before ripping it out. It was indeed the Memspan fuse. I still can't believe I haven't knowingly come across one in the past. Learn something new every day

Cheers guys

 

[littlespark]

UPDATE:
I went back, Isolated both at the Memspan switchfuse (thank you Lucien) and also at the main CCU (as an additional percaution), used my volt pen on the painted over switch in the bathroom, smashed the bloody thing open with my hammer, and did dead/live testing for real with my voltage tester before ripping it out. It was indeed the Memspan fuse. I still can't believe I haven't knowingly come across one in the past. Learn something new every day

Cheers guys

You opened a switch up with a hammer?

(Best Obi-Wan Kenobi voice)

“Young Padawan, you are now the Master”

 

[captaincaveman]

You opened a switch up with a hammer?

(Best Obi-Wan Kenobi voice)

“Young Padawan, you are now the Master”

Read the post - It had been painted over several times (including the actual toggle). I could have tried breathing on it to melt the paint away but a hammer seemed quicker

I ought to have used my club though - Caaaaaaaaaptain Caaaaaaaavemaaaaaan

 

[pc1966]

I could have tried breathing on it to melt the paint away but a hammer seemed quicker

Yes, a hammer and chisel job for heavy paint, or just skip the chisel part altogether!

 

[telectrix]

who needs a chisel?

 

[Baddegg]

How else do you open switches?