Open neutral in cooker

[Pretty Mouth]

A client has a Kenwood CK405 dual fuel range cooker, for which the smaller of the 2 ovens doesn't work. The elements tested out fine, but live tests showed that both N and L sides of the elements were at 230V to E, so presumably an open neutral.

I'm guessing it's a loose connection somewhere. However, as I'm led to believe that appliance wiring doesn't always follow the same rules that we follow, and that switching devices in the neutral are sometimes used, I thought I'd ask the forum if there was anything else that might have caused this?

 

[James]

it is possible that there is a thermal fuse in the N line.
I have seen this before, should not be too difficult to trace and test the N line back to incoming mains and find where the fault lies?

 

[Lucien Nunes]

That was my first thought too. Either a one-shot thermal fuse that has to be replaced after operation, or more likely a self-resetting bimetal one that has simply failed. Or possibly the normal thermostat. Or a burnt connector, which is not uncommon in appliances. Sorry, not much help.

 

[Pretty Mouth]

Thanks guys, I'll have a look next time I'm there

 

[brianmoooore]

One oven on my own DF range cooker quit last autumn. Found a one shot thermal fuse hidden under the insulation behind the back of the oven. A replacement of the same spec. restored operation as normal.
Could be the controller instead, or a burnt up spade connector. As already said above, failures of these are common, and it seems to be the norm to switch the neutral in appliances.

 

[timhoward]

As already said above, failures of these are common, and it seems to be the norm to switch the neutral in appliances.

I attended a call out recently where half a dual RCD board was off and the RCD wouldn’t stay on. It did stay on with the cooker MCB off.
IR tests at the oven showed 0.46 M which reduced the longer the test occurred, I saw it half.
It was mildly bothering me why this was happening with no element switched on, and also the reading seemed a bit high to be instantly tripping an RCD.
My guess was that it was N switched and there was enough moisture in the element to leak to earth and the same moisture was being driven increasingly near the L end.
(The appliance was under warranty so I didn’t dig further and they were happy enough to have sockets and heating back on.)