Non contact tester showing cooker live. Random shocks in kitchen.

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Ok. So a few weeks ago my wife got a shock off what she thought was the metal kettle we use plugged into the outlet which is also the cooker switch (a twin unit).
She binned the kettle as thought it was faulty and plugged the new kettle into another outlet in the kitchen.
This is now the same circuit as the toaster.
The toaster and kettle circuit also supplies the washing machine and dishwater.
The cooker circuit is different and wired to a different MCB.
Although the cooker is at the end next to the toaster and washing machine.

No RCDs in the house.

The other day she got a shock off the toaster (again so she thinks).
Now obviously he the toaster and kettle are double insulated so surely this is impossible.
Plus the toaster is a different circuit to the one the cooker is on (and old kettle WAS on)

So I’ve checked all the sockets and they show fine with the socket tester.

Just went and got a new non contact pen and checked the toaster (clear), kettle clear. Washing machine flashes on the control panel (as expected I guess) but no where else.

Now the cooker flashes the pen on every metal part even when not being used (but still switched in to power the clock)
Is this normal? When switched off it’s clear so the switch works!

When she gets a shock it’s only every so often (once a week) cannot be repeated (although she got two shocks in an hour today)
I havent had a shock yet!!

I’m wondering if the cooker is live and faulty and the shock she is getting is it being earthed by being near another earthed appliance?
It’s odd that the shocks are random and cannot be repeated.

Surely there should be no voltage detected on any part of the cooker ever.

I’m probably going to just get a professional in but would like some ideas consider first. A ex sparky friend is confused (although i have only just tested the cooker with the pen), he initially thought maybe a dodgy connection under load due to the randomness.

Any ideas (but mainly curious that the cooker which should be double insulated shows live) ?
 
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just a thought - could it possibly be static ?
I would suspect that "the shocks" very probably are. ... but, of course, on the basis of what little we know, we can't be sure about that.

Kind Regards, John
 
That’s what I thought too (static) , but generated by what?

Washing machine adjacent?

But back to my original question should the cooker light up the pen?
 
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what is the floor covering?

was she barefoot?

is she usually?

if not, what sort of shoes at the time of shock?
 
p.s.

the appliances you mention are not likely to be double insulated

they are more likely to be earthed

can you lay your hands on a multimeter?
 
Thanks.
Laminate floor over concrete slab.
Usually wearing slippers.

Yep. Have a multimeter.
 
Ok. So a few weeks ago my wife got a shock off what she thought was the metal kettle we use
Could we also get a description of the 'shock' from your wife?
Was it a short sharp shock with a visible spark, and audible 'crack' or was it more like a sustained, pulsing/buzzing sensation?
 
She just said it was both…. Like a pulsing then a crack.
Do you think she was “live” and then when touching earth either through the earthed toaster or “ground” got the shock as it discharged?

Ok. The plot thickens. She’s just told me that a pan boiled over a few weeks ago and tripped the Mcb.
That would imply a short internally enough to blow the trip.

Maybe that caused something to fail and started the whole problem.

Why she didn’t tell me that before.


So I’ve just put the multimeter between the cooker case and the earth on the toaster (can’t find a guaranteed earth nearby) and hey presto 235v

Faulty cooker???

The random “earthing” is probably proximity to earthed appliances and or different shoes…

But why would the mcb not blow all the time? Unless the earth connection inside the cooker “melted” ?
 
So I’ve just put the multimeter between the cooker case and the earth on the toaster (can’t find a guaranteed earth nearby) and hey presto 235v

Faulty cooker???
The cooker may be faulty, but there must be at least 2 serious faults present for such a situation to occur. Such as a fault inside the cooker causing the case to be live, and the earth connection to the cooker is defective or missing.

If the cooker is switched off at the isolator switch or the MCB in the consumer unit, does the voltage between it and the toaster disappear?
 
So I’ve just put the multimeter between the cooker case and the earth on the toaster (can’t find a guaranteed earth nearby) and hey presto 235v

Faulty cooker???

or the toaster

try the multimeter probes against the cold water tap, and the screws on various switches and sockets, compared to the toaster case and compared to the cooker. there should be no voltage from any of these against any pipe or tap, or the boiler casing, or any metal appliance casing.

if it is the cooker at fault, you MUST ISOLATE IT until the fault is identified and corrected.

see also https://www.standard.co.uk/hp/front/mp-s-daughter-electrocuted-6939286.html

how old is the wiring in your house?
 
Last edited:
Yes. Zero voltage when isolator switched off.

I’m sorry as she keeps telling me more things (the joy of forums)… she now tells me the trip went a couple of times, and then stopped failing.

What you say makes perfect sense, something making the case live, but why isn’t this being discharged to earth, is the other quandary. Could the mcb be faulty?

Maybe now is the time to just get a new rcb board and get the whole house earths checked.
 
Maybe now is the time to just get a new rcb board and get the whole house earths checked.

now is just the time to isolate the problem appliance and leave it isolated until the fault has been identified and corrected.

you have not told us anything to suggest a new CU is required. A new CU alone would likely not cure the fault anyway.

except that if you have no RCD, that would be an improvement.

RCBOs are preferable, one on each circuit.
 

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