2 Circuits, 1 MCB

[DanDobson]

Good evening all,

I get a decent amount of work from a kitchen company and do all the electrical work for them.
As expected each one has its challenges, but this job i've looked at today has a kitchen ring on a 32Amp MCB, and its own cooker circuit on a 32Amp MCB.

Once I isolated the cooker circuit to start making the necessary changes, when I tested I am still getting 150v between live and neutral? does anyone know why this would be?
I have used my old and new Fluke meters and my martindale volt meter to check one or other wasn't failing.

With all the issues ive come across in kitchen re-wires, I haven't had this yet.

Any help and ideas would be much appreciated

Dan

 

[ImpededLoop]

Had you disconnected any of the cables before you did the test? What do you get between the live conductors and cpc?

 

[Dave OCD]

When you say isolated do you mean just turning off the cooker circuit MCB ? If so I know this is unlikely but test on the outgoing terminal and see if the voltage is there, may just be the MCB not breaking properly ? Or remove the live from the MCB and test again at the other end of the circuit.

 

[Lucien Nunes]

my old and new Fluke meters and my martindale volt meter

Are any of these approved voltage indicators?

A voltage reading from a conductor that is supposed to be isolated (but is being made live by leakage) is rather meaningless as the actual voltage you read will depend on the meter's input impedance. Hence the importance of choosing the right test device...

 

[HandySparks]

I'm puzzled by the thread title.

 

[uksparks]

When you say isolated do you mean just turning off the cooker circuit MCB ? If so I know this is unlikely but test on the outgoing terminal and see if the voltage is there, may just be the MCB not breaking properly ? Or remove the live from the MCB and test again at the other end of the circuit.

It could be an mcb that's been covered in building carp and fouled up as you say, it wouldn't be unknown.

 

[Hellmooth]

I'm puzzled by the thread title.

Doesn't indicate 2 circuits on the 1 breaker in the post does it?

Could be ghost voltage, why would having 2 circuits in the same breaker make any difference anyway, they'd both be turned off?

 

[davesparks]

I opened the thread thinking we were going to go through the whole definition of a circuit debacle again.
But I was pleasantly surprised to see that actual we are going to go through the whole capacitive coupling thing again instead!

 

[Hellmooth]

My thoughts were the same!

 

[Deleted member 9648]

Good evening all,

I get a decent amount of work from a kitchen company and do all the electrical work for them.
As expected each one has its challenges, but this job i've looked at today has a kitchen ring on a 32Amp MCB, and its own cooker circuit on a 32Amp MCB.

Once I isolated the cooker circuit to start making the necessary changes, when I tested I am still getting 150v between live and neutral? does anyone know why this would be?
I have used my old and new Fluke meters and my martindale volt meter to check one or other wasn't failing.

With all the issues ive come across in kitchen re-wires, I haven't had this yet.

Any help and ideas would be much appreciated

Dan

You could always try verifying the integrity of the circuit by standard testing proceedures.

 

[Deleted member 26818]

Is anything still plugged in on the circuit?

 

[DanDobson]

Many thanks for help guys, was indeed a faulty breaker not breaking properly.

Apologies for the thread title, ive had loads of issues to sort in this house before I could actually start work on the kitchen and that was one of them. For some reason I was thinking of something different while writing the title.

I think I need an early night, thank god its friday.

Kind Regards

Dan

 

[DanDobson]

Yes my Martindale is an approved voltage indicator and was indicating 100V

 

[Dave OCD]

There you go, old Dave in sunnyish Cornwall diagnosed the problem lol. :biggrin5:

 

[Guest77]

Good evening all,

I get a decent amount of work from a kitchen company and do all the electrical work for them.
As expected each one has its challenges, but this job i've looked at today has a kitchen ring on a 32Amp MCB, and its own cooker circuit on a 32Amp MCB.

Once I isolated the cooker circuit to start making the necessary changes, when I tested I am still getting 150v between live and neutral? does anyone know why this would be?
I have used my old and new Fluke meters and my martindale volt meter to check one or other wasn't failing.

With all the issues ive come across in kitchen re-wires, I haven't had this yet.

Any help and ideas would be much appreciated

Dan

Yes I have a very good idea, have you tested between cores with 500 volts? have you also tested continuity ? have you confirmed there are no joint boxes sending cables elsewhere off the main ring? lets get back to basics.