Strange voltage on immersion controller

[richardspooner]

I've had a problem with my immersion heater and I've traced back to the switch. I'm getting strange voltage readings on the supply side (around 164v). I've tested my multimeter on a known good socket and I'm getting a reading of around 216V.

If I test the bare supply wires to the switch I get 164v. If I bridge to the negative on what I assume is the cable to the immersion I get a reading of 204V.

I've included a lablelled photo below to try and show what cables I am working with.....

Does anyone know why the voltages are all over the place??

 

[richardspooner]

More info here if anyone is interested... //www.diynot.com/forums/viewtopic.php?t=157375

 

[Steve]

Where is this switch in relation to the loft and your mersion?

Can you post a picture of your supply - cutout, meter and fusebox?

 

[Spark123]

They aren't live sticking out the wall like that are they
Your multimeter should read closer to 240v on a normal supply - maybe worth changing the battery.
Looking at the red / black wires to the immersion - are they a bit smaller than the supply wires?

 

[richardspooner]

Where is this switch in relation to the loft and your mersion?

Can you post a picture of your supply - cutout, meter and fusebox?

Will get those photos now. 5 mins.

 

[richardspooner]

They aren't live sticking out the wall like that are they
Your multimeter should read closer to 240v on a normal supply - maybe worth changing the battery.
Looking at the red / black wires to the immersion - are they a bit smaller than the supply wires?

No. Wires are isolated there.

All wires are the same size.

 

[Spark123]

216v just seems very low for a supply voltage.
Can test the resistance between the L&N on the cable to the immersion heater?
At the booster switch - if you connect the 2 reds together and connect the two blacks together in that block power on and very carefully test the volts between L & N and then between L & E what do you get?
I take it there is an isolator between that switch and the supply?

 

[richardspooner]

First things first.......here's the pics.

Secondly, from what I can determine, the supply side (before the switch) is directly from the MCB, then the output (don't know the right names sorry) goes up to the loft, through a fused swtch, then to the immersion.

 

[richardspooner]

Interestingly, as you can see I have bypassed the switch with that block. When I take a reading (just replaced the battery) with the multimeter, I get 26v with just the positive test lead, when I use the neg test lead the voltage drops off all together.

 

[richardspooner]

L&E or N&E are both giving reading >200V...............WTF?

 

[Spark123]

Edit - we both posted at the same time

 

[richardspooner]

Red to red only reads 22v

Red to red and black to black reads 0v. Can actually watch the voltage drop on the multimeter once you touch the black.

 

[Spark123]

Can you post a pic of how you have your multimeter set?
It is beginning to sound like the neutral is open circuit.

 

[Spark123]

Is there an isolator switch between the boost switch and the consumer unit? Can you do a similar test there, between L&E and N&E?

 

[richardspooner]

Can you post a pic of how you have your multimeter set?
It is beginning to sound like the neutral is open circuit.

If the immersion had actually burnt out all together would this break the circuit? So when I am testing across L&N in this scenario would I see the voltage drop? and on either side L or N it would show the right reading?