Kettle won’t stay on

[Tim+]

Our previously reliable electric kettle has taken to turning itself off a few seconds after turning it on. If I hold the switch down it boils as normal. It’s turning itself off long before and steam is generated so it can’t be the normal cut-out that’s tripping and only if the kettle is powered so it seems unlikely that it’s a simple mechanical fault.

Anyone got any ideas as to what might be wrong? I’ve had a quick shufty and there’s some surface corrosion on a spring disk that forms part of the switch but not a lot. Can’t see how/why that would limit the switch to a few seconds of functioning.

Tim

[Bob Eager]

If it's cordless, look at the contacts between the kettle and the base. They're usually concentric, so you can spin the kettle round to clean them.

DAMHIKT

[Nick Odell]

Just to add a couple of things to Bob Eager's post (which, by the way, is showing on Google Groups but doesn't seem to have arrived yet at ES)

These kettles are designed to be removed from the base after the switch has clicked off. Consequently, cheaply made kettles (which may still be expensive to purchase) often have very robust plating on the switch contacts but rubbish plating on the base contacts. Lifting the kettle before it has been switched off often causes arcing which leaves those base contacts pitted and hard to keep bright.

Some of the kettle bases are made from thermoplastics which gradually deform under the heat and the weight of the kettle. They can reach a point where the contacts are only just touching and a little bit of heating makes them drop down and fall away - such as when you start to boil the water. The centre contacts of the kettles I've come across all appear to have the same dimensions so the bases are interchangeable. I solved one kettle problem by swapping the faulty base with another with a smaller diameter and another by swapping the faulty centre hub from one into another.

I even had a kettle and base combination that I really liked so, when it collapsed into itself, I remoulded the base and stuffed the inside with more plastic so that it couldn't collapse again. I really don't recommend doing that unless you are a bit potty like me and I suspect it wouldn't meet safety standards any more.

Nick

[Davey]

I got his post from E-S marked as at 3:15, and that was about when I read it, before your post appeared, marked as 4:04.

[Tim+]

That would just stop it heating up, not make the switch click off.

Tim

[Tim+]

See my reply to Bob. The kettle is actually switching off, not just losing power.

Tim

[Tim+]

I’m not sure you’re right.

My kettles have a central pin (non-current carrying) that passes through into the base which switches the power off to the two annular contacts before the kettle is clear of them when it’s lifted.

Ours is a cheap Asda kettle which has kept us going for many year and has often been lifted off the base before it’s switched itself off. The contacts in the kettle base are in good condition.

A further clarification that may help with diagnosis though…

When I turn my kettle on, the LEDs come on, indicating power to the kettle. After several seconds a faint click comes from the bottom of the kettle itself (not the lift off base) and the LEDs go out and the kettle stops heating. The actual main switch that I depress to turn the kettle on stays in the on position.

It’s sounds like a stat or relay of some sort that is responding to current flow but it’s not at all obvious where it is.

I think I need to find a way of powering it up whilst I’ve got the kettle partially dismembered. ;-)

Tim

[Davey]

"Open Heat Surgery?"

[Joe]

Not being very helpful, but the switch mechanism has the extra complication of responding to the state of boiling, so the mechanical state keeping the switch on gets flipped off by a relatively small movement. You might be looking either for a fastening having loosened and made the mechanism 'hair trigger', or possibly that something has distorted with time and heat and now sits much closer to the 'turn it off' state.

It may take only ten seconds for a turned-on kettle to start making noise, and I suspect that low-level vibration will occur before it actually becomes audible.

[Tim+]

Except, it’s not the main kettle switch that’s clicking off, it’s something else in the base of the kettle that’s cutting the power.

Tim

[Joe]

Thermal cutout in the event of boiling dry? Any limescale in the bottom of the kettle that might allow the element to get hotter than intended? Otherwise possibly the cutout is actually faulty.

[Bob Eager]

No, it was one of the sensor contacts. Worked for me on a lot of occasions.

[Animal]

there isn't anything else that's at all likely to do that. Dirty contacts would heat the thing that turns off when hot, so it might be that. Sometimes they can be cleaned enough just by operating the switch many times vigorously without power.

[John J]

At current cost to replace with an El cheapo supermarket kettle I wouldn't waste more than five minutes of my time on it.

[Paul]

There's an example of a thermal cutoff in the bottom of this one.

Not that seeing it open, is helping me.

I presume a worn item with wear and tear on it, would give away its secret that way.

It could be that the element has come loose of the base (corrosion), and the water is no longer sinking the heat.

Paul

[The Natural Philosopher]

Scaled up kettles dont respond too well, either

[Jeff Gaines]

Yes, I have that with mine - opposite issue in that if it's scaled up it doesn't turn itself off.

[Tim+]

Thanks for that! Very helpful.

Tim

[Tim+]

It’s already been replaced, but I’d still like to fix it if possible (as a reserve) as it’s otherwise a nice kettle with a lid mechanism that looks better constructed than its replacement.

Tim

[GB]

We have a Bosch variable temperature kettle, and I agree with Bob that cleaning the contacts has extended the life of the kettle by years.