Burnt out plug

Mrlazy81

Any idea why a plug for an immersion water heater has burnt out? The plug itself became incredibly hot and has left burn marks on the socket where the bottom two prongs were inserted.... the inside of the plug is black mostly where the neutral wire goes in, but also where the live wire goes... all wires were secure in there correct place....

LandyAndy

Mrlazy81 wrote: »

Any idea why a plug for an immersion water heater has burnt out? The plug itself became incredibly hot and has left burn marks on the socket where the bottom two prongs were inserted.... the inside of the plug is black mostly where the neutral wire goes in, but also where the live wire goes... all wires were secure in there correct place....

Because immersion heaters aren't designed to run off a 13A socket?


Lucky escape for you.

TheCyclingProgrammer

Yes, I thought immersion heaters normally had their own circuit. Our old one did.

Of course, I guess there's a chance that it's a very low power immersion and therefore within the 13amp rating of the plug, in which case the next culprit may be loose connections inside the plug causing overheating, but either way I'd be calling out an electrician to check everything.

Wookey

An immersion heater should really be hard wired on a separate circuit, it will use about the same power as your kettle but whereby a kettle is boiled and switches of the stat inside the immersion will constantly be switching of and on as it maintains temp, lose plugtop connections between the plug and socket can then generate heat or in worst case scenario arcing which overtime will degrade the viability of the plug and the socket.

Geoff1963

The immersion heater should have some kind of rating panel. I'd guess nearer 20 Amps.

datostar

I'd want to be certain that it is actually on a fused circuit as well. Surprising to get that amount of heat without tripping/blowing a fuse.

nofoollikeold

Virtually all domestic immersion heaters are 3Kw. These require a 13A supply, and should be connected directly, via a fused connector unit with double pole switch, back to a separate fuse on the consumer unit.

They should NOT be plugged into a socket on a ring main. As stated earlier, they can be on for long periods, and can switch on and off many times during the course of a day. The connection between flat pins on the plug and the socket is subject to corrosion and dirt. This increases the resistance, resulting in heating, which makes the problem worse and so on.

Get it re-wired by a qualified electrician.

keith969

If it's wired using stranded wire, what can happen is if the wire has been stripped of insulation carelessly, some strands will have broken and so at the point where the wire enters the L/N pin it is thinner - and so more resistive - and so gets hotter than it should.

Should be really run off a 15A circuit though.

LandyAndy

I see the op posted and never came back.

Living up to his name or worse............

[Deleted User]

datostar wrote: »

I'd want to be certain that it is actually on a fused circuit as well. Surprising to get that amount of heat without tripping/blowing a fuse.

The plug itself has a fuse, but that won't prevent a fire. The overheating will be caused by high contact resistance somewhere in the plug, in which case the current is lower, not higher, and consequentially not going to blow a fuse.

Ectophile

If anything, the fuse in the plug makes things worse. A 13A fuse run at 13A for a few hours can get really warm. That just adds to the heat from the plug contacts.