Current in ceiling switch neutral wire ?

[picaso]

The 15 year old 50 Amp DP Pull Cord ceiling Switch for my bathroom shower stopped working this morning. On internal inspection a crack ran through it. I tested the live and neutral wires and found both the black neutral and red live wires lit up my live wire detector screwdriver.
Should there be a current in the black neutral wire if the appliance its connected to (shower) is switched off? I ask as I have tested other installations and found no current in the black neutral wire when the appliance is not in use.

I should add that I have made a temporary fix by attaching the neutral and live wires via a block connector and the shower is working again. Also, the shower has its own separate fuse box.

 

[ban-all-sheds]

The 15 year old 50 Amp DP Pull Cord ceiling Switch for my bathroom shower stopped working this morning. On internal inspection a crack ran through it. I tested the live and neutral wires and found both the black neutral and red live wires lit up my live wire detector screwdriver.

Which shows how useless and therefore potentially dangerous those things can be.

https://www.diynot.com/diy/search/17266650/?q="neon+screwdriver"&o=date&c[node]=8

https://www.diynot.com/diy/search/17266658/?q="magic+wand"&o=date&c[node]=8

Should there be a current in the black neutral wire if the appliance its connected to (shower) is switched off? I ask as I have tested other installations and found no current in the black neutral wire when the appliance is not in use.

Those devices don't detect current flowing - they signal the presence of a voltage, but it could well be an induced one, and in any event they don't actually measure it.

 

[EFLImpudence]

Firstly, "neon" screwdrivers detect voltage, not current, and should not be relied on for detection nor proof of absence of voltage.
They do not work as stated.

Secondly, it is not clear from your description what the problem was or what you have altered.
As it is now working you have obviously connected something that was not connected before.

 

[picaso]

Which shows how useless and therefore potentially dangerous those things can be.

Those devices don't detect current flowing - they signal the presence of a voltage, but it could well be an induced one, and in any event they don't actually measure it.

So what is an Induced voltage.

 

[EFLImpudence]

To save a bit of typing CLICK.

 

[picaso]

So am I correct in thinking the induced voltage could be due to a fault in the switch causing a magnetic anomaly. I have not retested the live and neutral since bypassing the switch and wiring them to the block connector, but I will test them when I install a new switch. Electricity is so much fun.

 

[EFLImpudence]

So am I correct in thinking the induced voltage could be due to a fault in the switch causing a magnetic anomaly.

No. Anyway, it does not matter.

I have not retested the live and neutral since bypassing the switch and wiring them to the block connector, but I will test them when I install a new switch. Electricity is so much fun.

You did not test them in the first place. You just pointed a useless instrument at them.

Also, you have not told us what was wrong.
You said the switch was cracked - so, it should be relaced.
You said "I have made a temporary fix by attaching the neutral and live wires via a block connector" so where were they connected, or not, when the shower was not working?

 

[EFLImpudence]

Oh. I am sorry.

I just realised you said you have bypassed the switch.

I would think then you need a new switch.

 

[picaso]

OK so the live wire screwdriver tester is useless. I only use it to identify which wire is live, which is all that can be done with it anyway and in this case as already stated, both N and L wires were causing the useless instrument to glow, which I thought was odd as I was only expecting the L to be carrying a voltage.

Obviously the switch no longer works and when the cored is pulled, there is no click, just the travel in the spring. I removed the cover and could see a long hairline crack in the terminal housing. As the shower was not working, I removed the in and out L and N wires from their positions in the switch and connected them together in an external block and the shower now works perfectly, just as it did before the switch became faulty. The only problem is a permanent live feed into the shower. I have left the earths still connected in the switch, which I now realise could be a mistake due to the hair line crack apparently causing the the problem with live and neutral wires. I hope this is clearer for you. I will purchase and fit a new switch tomorrow, assuming I do not electrocute myself in the process. If you do not hear from me... assume the worst.

 

[picaso]

Just read your second reply after had been typing my long reply.

 

[EFLImpudence]

Sorry about that -

but that was much clearer than the first post.

See you tomorrow.

 

[winston1]

The only problem is a permanent live feed into the shower.

Which is not a problem. There is no requirement for local isolation. You can always isolate it at the CU anyway.