3kw comet kiln-plug socket renewed 3 times...

Well if it baffled your professional electrician, there's your problem.

What subnormal idiot thought that a damp kiln room could have any bearing on socket condition/ temperature 20 feet away?

AB

And just because a professional electrician was used it doesn't mean that the socket wasn't replaced by the cheapest he could source rather than the best quality available.

A plug/socket getting hot is a sign of inadequate low resistance connection or it being under-rated.

What socket are you writing about. A standard 13A socket/plug? (Although I can't see how you would fit a plug to an amoured cable). Is the switch heavy duty as used for a electric oven?

There appears to be two versions of the Comet Kiln, the ECO which draws 3kW which should be fine using a 13A plug in a standard socket. The other is a 5.5kW model for which a plug and socket is totally inadequate. There shoul d be a ratings plate somewhere on the kiln check the wattage, although I wo uld have thought your professional electrician would have checked that firs t.

Richard

Good point.

The other thing I would suggest even for the 3 kW model is to get your sparks to fit a "cooker" type breaker switch and then an industrial type plug and socket like this:

(This is what I did in a friend's business unit after he was getting short life even from MK plugs and sockets that were running with a high duty factor).

Or wire it straight in - as you would do with a cooker. My big glass-fusing kiln (7kw or thereabouts) has its own cable straight back to the consumer unit, a big isolating switch on the workshop wall, and the same 'big cable' wired direct into the contactors.

Kilns and standard plug-type connectors don't mix - and, as they're often left running, unattended - it's worthwhile doing the job properly and safely.

I assume the 20ft cable is from the house supply to the socket in the kiln room - and therefore almost certainly irrelevant to the problem. Why not wire the kiln directly into a fused connection box with an two pole switch? The socket is failing either because it and/or the plug are cheap and nasty, or because of pervasive damp and corrosion.

Probably a good idea, but why does he need a plug and socket for the kiln anyway?

Its quite obvious that something in that circuit is underrated for the current being drawn, and once some plastic bit starts to melt you get poor and poorer contact, even arcing in the end, completely trashing the socket. If a plug is getting warm that is a good bit of diagnostic help. The pin that is getting hot is obviously doing so due to underrated connections. Look in the plug or whatever it is that plugs into the socket which gets damaged. it is entirely possible that the body of the plug is unaffected if its a higher melting point plastic. I had an issue like this with one of those so called plug in mechanical timers, the one where you put pins in holes. When I opened it up the short bit of brass from the live pin to the switch had been riveted to either end and this had oxidised and heated up the pin as a result. Load of rubbish. I only had a 3K fan heater on it! Brian

Yes, good point about wiring in direct. I used plugs and sockets for my friend because they are in heater supplies switched by temperature controllers. This way, if either a heater or a controller fails, working items can be switched over to a spare device.

But perhaps worth remembering if you have something more portable like a big welder, which you might want to put away.

newshound was thinking very hard :

Your first step, ought to be to check the actual current drawn or check the rating plate on the back of the kiln. If it is just over the 13 amps, likely it would not blow the plug top fuse, but damage the plug and socket over time.

One solution for the 'just over 13amps' is to swap the plug and socket for a 16amp blue plug and socket. These are unfused, so the MCB would need to be changed if necessary for a 16amp if it is not already a

And the OP may need to watch the implications for her insurance of anything which departs from the regs/manufacturer's requirements. And double and redouble that if she is using it commercially and has employees who use or are around the kiln, run courses where people use it, ...

Despite being rated at 13 amps, most sockets and plugs aren't happy to carry that for very long periods. They are a domestic connector and really for intermittent use at full capacity. As with a kettle or washing machine etc. Hence things like 13 amp water heaters normally not plugged in, but hard wired. Same sort of thing with storage rads.

Even more so if cooling to the socket/plug is restricted in any way.

The answer is to go for an industrial 16 amp plug and socket - if indeed it has to have a plug/socket arrangement.

I read it as the socket/plug is next to the kiln where the socket is at the (shed?) end of the 20ft of armoured cable.

There is also a 32 amp, which is perhaps better if it is protected by a

possibilities: the kiln draws more than 13A, maybe due to some turns of the heating wire being crossed. plug or socket not of best quality fuse not completely clean or not best quality

Also as said, plugs & sockets don't do well running at 13A for long times. Try an FCU.

NT

Indeed. 3kW is pushing it on a standard plug and socket for a near continuous load. They are fine for intermittent loads like kettles.

ISTR there is a revision that recommends no portable appliances with load >2.4kW due to the fragile nature of nominally 13A plug and sockets.

Or hardwired fused spur like a hot water cylinder immersion heater.

That could prove a bit of a shock hazard as it's the wrong gender.

Try

I can't see anything official (and I didn't try that hard) but a supporting data point is fan heaters. Usually 2kW max, sometimes a little more, but I've not seen 3kW.

Cheers

I don't know where it is in what legislation but it came up in conversation with a sparks doing some alterations at out VH.

I have a 3kW fan heater and it has cooked a plug and socket not quite to the point of failure but more than I was comfortable with one cold day. Enough to significantly discolour and distort the plastic casings.