Immersion heater faulty (probably). Is my logic correct?

Vomityspice

My ongoing problem is continuing. My initial thoughts were that the thermostat was defective, given the ominous black burn mark on the casing that had melted it. However, changing it has not remedied my problem, so this is leading me to believe it is a defective immersion element.....

I have tested for resistance and get 19.7 ohms, I has also tested for continuity and there is (L + N). However, when I use my electrician screwdriver , there is power on the brown live cable and this goes through the stat to the immersion element, however there is nothing at the neutral? (If I switch on the immersion heater)

Am I right in concluding a faulty element? Or are there other tests I can do with my multimeter to confirm it is knackered?

Ectophile

19.7 ohms sounds about right. Wattage = voltage squared, divided by resistance, and 240 x 240 / 19.7 = 2.9kW.

I wouldn't expect a neon screwdriver to light up on the neutral. It takes about 80V to light a neon, and if the neutral was 80V above earth, then there would be something wrong with your house wiring. If the neon doesn't light when touching the neutral, then that's correct.

It's always possible that there's a bad contact somewhere, which only shows itself when the element is hot.

Ideally you'd want to measure the current through the element and watch how that changes over time. But the only safe way I can think of to do that is using a clamp ammeter, which isn't the sort of thing most people would have.

Vomityspice

Luckily my friend's son is an electrician, who I can call for these types of events. I just don't want to waste his time if I can work out what is wrong