Bit of advice on wiring of an electric shower

[dirty harry]

I'm installing a new bathroom suite for a customer but they arranged for the electrician to come in and sort out the electric supply for the shower. However, I am a little concerned as to how safe he has left the wiring for the new shower and, not being an experienced electrician, I would appreciate some advice.

I had already disconnected the original electrical supply for the shower and made it safe and the electrician has connected this supply to the "mains in" terminals on a fused switch outside the bathroom. From this switch a new length of wiring goes through a stud wall to a pull-cord ceiling mounted switch next to the shower. Then there is a final length of wiring from the pull-cord switch for me to connect to the shower when I install it.

However, despite checking that the fused switch outside the bathroom and the pull-cord switch next to the shower are both off, I have tested the wire he has left me (bare-ended I would add) and it is showing as live. How can this be the case if the two switches are both off?

Any clues would be appreciate.

 

[riveralt]

Not sure what you mean by a mains in terminal outside the bathroom.

The shower circuit should run from the MCB and RCD at the Consumer Unit to the 45Amp dual pole pull switch in the ceiling and then onto the shower itself.

Sometimes people will fit a dual pole 45Amp switch outside the bathroom as well.

Can I ask how you are testing that you have a live wire - what with and what colour cables?

Does the live wire stay live when you switch the MCB off?

 

[wingcoax]

Which wire is showing"live"?

 

[dirty harry]

Not sure what you mean by a mains in terminal outside the bathroom.

The shower circuit should run from the MCB and RCD at the Consumer Unit to the 45Amp dual pole pull switch in the ceiling and then onto the shower itself.

Sometimes people will fit a dual pole 45Amp switch outside the bathroom as well.

Can I ask how you are testing that you have a live wire - what with and what colour cables?

Does the live wire stay live when you switch the MCB off?

Hi, thanks for the quick reply. Apologies for the slightly confusing message! I was referring to the Live and Neutral terminals inside the 45A fused switch which are marked as "mains in".

Because the original supply was not long enough to reach the new pull-cord switch and a junction box wasn't deemed safe, it was wired into the 45A switch outside the bathroom first, before going through the stud wall to the pull-cord switch, and then onto the shower. I have used a standard mains tester which lights up when I touch the red/black/earth wires which the electrician has left for me to connect to the shower unit itself. However, as I said before, both the 45A and pull-cord switches are off.

The wire is not showing live when the MCB is off as I have turned this off to make the unconnected wire safe until I connect it to the shower.

 

[pjcomp]

"Lights up" implies a volt stick - bin it and get a meter which measures voltage and current instread of something which responds to the power in a watch battery.....

PJ

 

[dirty harry]

"Lights up" implies a volt stick - bin it and get a meter which measures voltage and current instread of something which responds to the power in a watch battery.....

PJ

I appreciate using a standard voltage tester is not as effective as a meter, but nonetheless I would not expect the LED in the tester to light up like a christmas tree when I touch the ends of the wire, bearing in mind both the 45A and pull-cord switches are turned off

 

[sparkwright]

Have you tested at the 45 amp wall switch outside the room?

You can check both the feed and load side, and isolate power at consumer unit.

Same with pull switch.

Might give you some idea.

 

[riveralt]

The wire is not showing live when the MCB is off as I have turned this off to make the unconnected wire safe until I connect it to the shower.

The 45Amp switch and pull switches you describe sound like they are dual pole and therefore should disconect the power - in this case at two points.

The tester you have described is not really suitable to dermine what the problem might be.

Firstly, with the power off check that the cable from the MCB is wired correctly. 45amp switches have a load and supply side - check that they have been wired up the right way - without teaching you to suck eggs the supply side should be from the CU and the load side toward the shower or in this case the next switch. It is possible that they may have been reversed - so on is off and off is on etc.

If it has been wired correctly, and the switches still do not stop the power then it could be that the switches are broken (unlikely). Rather than start to check each cable with a multi-meter I would get the electrician back to check the circuit.

 

[dirty harry]

"The 45Amp switch and pull switches you describe sound like they are dual pole and therefore should disconect the power - in this case at two points."
Yes, they are, and no, they are not disconnecting the power, therein lies the problem!

"The tester you have described is not really suitable to determine what the problem might be."
Agree, it is only a basic one suggesting that there is a live feed at the end of the wires.

"Firstly, with the power off check that the cable from the MCB is wired correctly. 45amp switches have a load and supply side - check that they have been wired up the right way - without teaching you to suck eggs the supply side should be from the CU and the load side toward the shower or in this case the next switch. It is possible that they may have been reversed - so on is off and off is on etc."
I have checked this, the incoming cables to the supply side of the 45A switch are connected red/live and black/neutral, plus earth, and the load to the shower mirrors this.

"If it has been wired correctly, and the switches still do not stop the power then it could be that the switches are broken (unlikely). Rather than start to check each cable with a multi-meter I would get the electrician back to check the circuit."
The pull-cord is a new switch and the 45A is the old one that worked ok before.

Sounds like I need the electrician back to check the circuit

 

[Monkeh]

Or you could just get a proper voltage tester instead of a little stick which lights up if you wave it around your hair.

 

[Chri5]

You really are wasting everyones time stating wires live having used only a chinese neon based volt test screwdriver.

They pick up weird fields from any and everywhere. If you really are convienced the wire is live call back the spark, and if he proves that they are not live and he did the correct job, 1st time then accept his £50 call out charge.

Might you have access to a multimeter that you could borrow and actually confirm what's going on with a decent test instrument ?


Aside from all that I take it the shower circuit works via an RCD unit because that is a firm reg / rule and MUST be done.

If the main CU han't got an RCD bar (s) then has the spark fitted a rcd based mini CU at the junction you mention outside the bathroom ?

 

[dirty harry]

OK, I have taken your advice and acquired a digital multimeter. However, I would appreciate someone confirming which settings I require before I test anything. I am aware that the black probe/lead goes in the COM hole and the red probe in the V hole, but where do I go from here?

Thanks.

 

[Chri5]

Volts ac range near to 230v.

 

[riveralt]

OK, I have taken your advice and acquired a digital multimeter. However, I would appreciate someone confirming which settings I require before I test anything. I am aware that the black probe/lead goes in the COM hole and the red probe in the V hole, but where do I go from here?

Thanks.

You know that when the MCB is off the whole circuit is dead. Leave it so.
Turn you multimeter dial to Volts.
At the first outside the bathroom switch test between the supply line/live and earth or neutral - you should get no volts.
Turn the power on at the MCB and do the same test - you should get 230/250v.
Turn the switch on and test on the load side - line and earth or neutral you should get 230250 v

Turn the switch off and do the same test you should get zero volts.

Time for work!

 

[dirty harry]

OK, I have taken your advice and acquired a digital multimeter. However, I would appreciate someone confirming which settings I require before I test anything. I am aware that the black probe/lead goes in the COM hole and the red probe in the V hole, but where do I go from here?

Thanks.

You know that when the MCB is off the whole circuit is dead. Leave it so.
Turn you multimeter dial to Volts.
At the first outside the bathroom switch test between the supply line/live and earth or neutral - you should get no volts.
Turn the power on at the MCB and do the same test - you should get 230/250v.
Turn the switch on and test on the load side - line and earth or neutral you should get 230250 v

Turn the switch off and do the same test you should get zero volts.

Time for work!

Time to test! Cheers