Just got back from overseas, to find the plug on my immersion heater has burnt/melted. Only recently moved into the house; the previous owner had fitted a standard plug in mechanical timer to control the immersion heater. I know this is not a good setup, and assume a fault had developed.
I can’t get an electrician in for a week to replace the setup with a proper wired in timer, but in the meantime want to replace the damaged plug with a new one, so that I have hot water (just switch on the heater for periods).
It depends on the rating of the immersion heater. If it is the usual 3KW then this is 13Amps on 230V mains.
So a GOOD 13A plug fitted with a genuine 13A fuse will do as a temporary fix. Check also for any damage to the socket - any discolouration at all is a bad sign. Check also the wire in the lead to the heater is thick enough and not tarnished where it is clamped in the plug, it should also have a heat resistant insulation and not pvc.
However, there are a lot of cheap and nasty fake plugs and fake fuses around that are dangerous and not up to 3Amp let alone 13A. Look at how well the plug is made, especially if bits are riveted together (can work loose with thermal cycling and exercise etc) rather than spot welded, and check for lack of good grip on the fuseclips. Also, if any of the working contact surfaces are badly tarnished then they might have a higher resistance, and while the current will flow thanks to plenty of oomph from 230V some of that might be spent cooking the pins and the socket.
Your electrician should be able to advise you on all this.
Between the socket and the plug, there was a plug in mechanical timer similar to this:
The visible damage is to this and the plug, with no damage visible to the “plug in” side of the timer and the wall socket itself. When I found it, it was clearly in the “off position” and cold.
I’m just going to replace the plug. The previous house owner was a plumber.
I wonder why the fuse box did not trip. Most of our electrics are made in China but sometimes they are defective. Could be a loose wire in the wall socket causing the overheat. By all means put a new plug with 13 amp fuse for now but keep an eye on it. Do not leave the house with it switched on !
It all looks to be the original wiring from when the house was built, circa 1975. Non-fused socket. Pretty old plug. Local electricians don’t seem to want the work.
There have been a few house fires recently where the fuse box has been at fault. Defective Chinese imports it appears. If the house has recently been purchased there should be a safety certificate for the electrics. Might be worth contacting the electrician who gave the certificate for an explanation.
