Help - melted plug - why?

[Dan White]

Hi - hope someone can help.

First, quick bit of background. I clean ovens for a living and have a tank in the van for cleaning oven parts. It has a regular 240v imersion element in it which I heat up each morning.

It's connected to an 13a extension cable which is plugged into an outdoor socket.

The outdoor socket is connected to a plug socket inside the house (I drilled through the wall and plug the socket into the household socket. Not ideal, I know. But have been advised it's safe).

Now as I'm lazy I fitted a wifi plug so I can turn it on from bed. It was on for about an hour each morning. I have left it on all night by accident a couple of times, it the element has a thermostat, so presume it wasn't running constantly.

Checked the plug his morning and discovered that it had been getting very hot and had melted the plug to the socket. Everything worked, and nothing had tripped.

Anyone know the likely cause?

 

[Pete999]

Moulded plugtop probably a loose or damaged fuse holder, cut it off and fit a replacement, the socket looks like it needs replacing as well

 

[westward10]

From the burn pattern it does appear to be the fuse part of the plug which has caused the damage.

 

[Dan White]

So def nothing todo with wifi plug (it only turns off 'neutral', so live and earth are always connected and 'open'.?

 

[westward10]

How many kw is the heater.

 

[Dan White]

Yeah, only the fuse area is damaged - the pins are all perfect.

 

[Pete999]

So def nothing todo with wifi plug (it only turns off 'neutral', so live and earth are always connected and 'open'.?

Only turns OFF the N how come? could have something to do with the problem, not sure how or why just yet, the switch in single poll circuit should be in the phase conductor. For some reason you say the N is switched, needs sorting PDQ

 

[westward10]

What kw is the heater.

 

[Dan White]

3kw

 

[Dan White]

Only turns OFF the N how come? could have something to do with the problem, not sure how or why just yet, the switch in single poll circuit should be in the phase conductor.

That's how the wifi socket works. I only noticed as I connected my campervan to the outdoor socket extension - then tested the camper sockets prior to us going away in it. The tester said there was no N. It came on when I realised I hadn't turned the wifi socket on. And that's when I discovered the melted plug. (Hope that makes sense)!

 

[westward10]

You sure you have correct polarity at the socket.

 

[westward10]

If that is loading the plug at 3kw you are over loading it.

 

[Dan White]

If that is loading the plug at 3kw you are over loading it.

Arse. So what's best practice?

 

[Dan White]

You sure you have correct polarity at the socket.

 

[Midwest]

At least we know that Kieron never installed the outdoor socket, 'cos its not flushed in

 

[Midwest]

What about the Wi-Fi socket?

 

[Midwest]

OP, did you purchase the immersion heater/plug top & flex set up, or is it something you put together yourself ?

 

[Dan White]

What about the Wi-Fi socket?

Yeah, everything's wired correctly (polarity-wise)

 

[Pete999]

Arse. So what's best practice?

It's a RECOMMENDATION ONLY that anything over 2KW should be on a dedicated circuit ie not the RFC.
Loose connection at the fuse holder N switched Off arcing at the plug top?

 

[Dan White]

OP, did you purchase the immersion heater/plug top & flex set up, or is it something you put together yourself ?

I bought the immersion - to which I connected the flex and plug. Bought the extension (the highest rated one they did in Homebase) and the wifi thing from Maplin's.

 

[Dan White]

It's been connected for the last 3 months and has worked perfectly (or so I thought). Feel a bit bad that I've only just checked the plug!

 

[Midwest]

The moulded plug and flex, where did that come from?

 

[westward10]

It isn't the best idea to load a 13A plug up to 3kw and I suspect this has been occurring for some time judging by the damage.

 

[Dan White]

The moulded plug and flex, where did that come from?

Homebase.

 

[Midwest]

I think a re-think is necessary. As its your business, I would suggest employing an electrician, and your set re-designed.

 

[Dan White]

It isn't the best idea to load a 13A plug up to 3kw and I suspect this has been occurring for some time judging by the damage.

So how to I safely get power to the immersion? Need to be able to connect and disconnect via plug as it's in a van!

The other chap who I do this with has a less manly flex and although his gets hot, it's not meeting hot.

 

[Dan White]

I think a re-think is necessary. As its your business, I would suggest employing an electrician, and your set re-designed.

Fair point. Main problem it actually finding one who will come and look at the job. Have been let down consistently by tradesmen of all descriptions countless times over the last couple of years. I'm always courteous, and expect to pay what the job costs - but it seems that most sparkies have more work than they need, and don't even want to quote for work!

 

[Pete999]

So how to I safely get power to the immersion? Need to be able to connect and disconnect via plug as it's in a van!

The other chap who I do this with has a less manly flex and although his gets hot, it's not meeting hot.

Do you leave the flex coiled up when in use?

 

[Dan White]

Do you leave the flex coiled up when in use?

Definitely not!

 

[Wilko]

Hi - observation is the 13A plug melted when used at about 13A. A 13A fuse won't blow when there's a 3kW load and no fault, but maybe there was a bit of corrosion/tarnish on the 13A fuse and that made it a bit more resistive and so it ran hot? Anyway, perhaps a new circuit from your CU with 16A socket and plug would fix this?

 

[Dan White]

Hi - observation is the 13A plug melted when used at about 13A. A 13A fuse won't blow when there's a 3kW load and no fault, but maybe there was a bit of corrosion/tarnish on the 13A fuse and that made it a bit more resistive and so it ran hot? Anyway, perhaps a new circuit from your CU with 16A socket and plug would fix this?

View attachment 37691

Would a 16A socket and plug suffice? - running a new circuit off the CU would be a ball ache due to its location.

 

[static zap]

Does this "Neutral" issue mean it will dislike you fitting an RCD to external sockets ?
(very un-fit product)

 

[Pete999]

Hi - observation is the 13A plug melted when used at about 13A. A 13A fuse won't blow when there's a 3kW load and no fault, but maybe there was a bit of corrosion/tarnish on the 13A fuse and that made it a bit more resistive and so it ran hot? Anyway, perhaps a new circuit from your CU with 16A socket and plug would fix this?

View attachment 37691

ON a dedicated circuit though

 

[Midwest]

Would a 16A socket and plug suffice? - running a new circuit off the CU would be a ball ache due to its location.

As Pete mentioned earlier, informative guidance in the wiring regs is loads of more than 2kW, should have their own dedicated circuit, like most storage water heaters are on, probably for the reasons you've encounter. As well as putting a load on your ring circuit, which might unbalance things.

Another consideration, is what type of supply you have, as I assume you set up is somehow fixed into your van?

Edit; Pete got there first

 

[Pete999]

Hi - observation is the 13A plug melted when used at about 13A. A 13A fuse won't blow when there's a 3kW load and no fault, but maybe there was a bit of corrosion/tarnish on the 13A fuse and that made it a bit more resistive and so it ran hot? Anyway, perhaps a new circuit from your CU with 16A socket and plug would fix this?

View attachment 37691

ON a dedicated circuit though

Would a 16A socket and plug suffice? - running a new circuit off the CU would be a ball ache due to its location.

If you're going to use a 16 Amp plug and socket, then it's a dedicated circuit

 

[Dan White]

Does this "Neutral" issue mean it will dislike you fitting an RCD to external sockets ?
(very un-fit product)

I don't know? Would it?

 

[westward10]

It has little to do with the fact it should be on a dedicated circuit but more that the plug top fuse has endured excessive current but a 16A socket is the solution.

 

[Pete999]

It has little to do with the fact it should be on a dedicated circuit but more that the plug top fuse has endured excessive current but a 16A socket is the solution.

Of course it does

 

[Midwest]

I don't know? Would it?

The Wi-Fi plug thing, isolating the neutral but not the live, cannot be right. This would turn 'off' anything connected to, but the device would still be 'live'. I doubt very much, if this is how it's designed. So you either have a connection problem, or your 'testing device' is wrong.

 

[Dan White]

Another consideration, is what type of supply you have, as I assume you set up is somehow fixed into your van?

Edit; Pete got there first

It goes to a plug fitted to the flex coming out of the immersion element. It's never got hot, just slightly warm.