Help - melted plug - why?

[Dan White]

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.

It's the tester pictured above - simple 'plug' with LEDs

 

[Midwest]

It's the tester pictured above - simple 'plug' with LEDs

What does it show, when plugged into the socket without the Wi-Fi thing?

i.e. socket turned off?

 

[westward10]

Of course it does

Why it isn't a fixed appliance even though it is an immersion element, it is essentially being used as a portable appliance plugged into a socket. You could have installed a dedicated 13A socket for it and you would have the same result. My kettle is rated 2.75 - 3.0kw so does that need a dedicated circuit.

 

[Midwest]

Why it isn't a fixed appliance even though it is an immersion element, it is essentially being used as a portable appliance plugged into a socket. You could have installed a dedicated 13A socket for it and you would have the same result. My kettle is rated 2.75 - 3.0kw so does that need a dedicated circuit.

But your kettle is unlikely to be on for long periods of time.

 

[Pete999]

Why it isn't a fixed appliance even though it is an immersion element, it is essentially being used as a portable appliance plugged into a socket. You could have installed a dedicated 13A socket for it and you would have the same result. My kettle is rated 2.75 - 3.0kw so does that need a dedicated circuit.

The kettle is only used for very short periods, Matey's element is on for longer, If you intend sticking a 13 Amp socket on a dedicated circuit and you know what it's going to be used for, in this case a 3KW water heater then quite frankly you are wasting your time, do it right the first time.

 

[Midwest]

The guidance for 2kW dedicated circuit, is only informative in App 15, granted.

 

[westward10]

Very true with regards to the kettle but the Regulations for 2kw is not for portable appliances and the cause of this problem was pushing the 13A fuse to its limit for prolonged periods of time.

 

[Midwest]

+ its only mobile 'cos it's sat in the back of his van

 

[Pete999]

The guidance for 2kW dedicated circuit, is only informative in App 15, granted.

I realise the IET don't have all the answers but in this case I think they have it right on the nail.

 

[Pete999]

+ its only mobile 'cos it's sat in the back of his van

Makes no odds

 

[Midwest]

Makes no odds

I was trying to make merry Pete

 

[Pete999]

I was trying to make merry Pete

Sorry Mate understood

 

[Richard Burns]

From an electrical point of view it would be best to have a specific 16A radial circuit for the heater on a higher rated (16A+) plug and socket arrangement.
The rating of the immersion means that it is pulling the maximum current that a BS1363 socket should take so any slight anomalies may cause melting such as you have seen. The same thing happens with standard immersion heaters on plug and socket or fused spur arrangements.
With the circuit installation you have you are unable to avoid requiring a 13A fuse at some point, presumably the wifi socket may be fused, the plug in the wifi socket will be fused and in the current set up the plug on the outside is also fused.
Each fuse (and each connection) is a potential point of failure.
The wifi socket must also be close to its rated limit as they are often limited to 10A or even 5 A.
The simplest solution would be to have a 16A socket installed outside instead of the double socket and still plugged in as you have it now inside, however this will only transfer the possibility of failure to the wifi socket and the plug which is used inside and will not address the heavy loading on the ring, although if it is only used at night the loading on the ring will probably be low.

 

[westward10]

I believe somewhere there is a requirement for immersions not to be on plug tops but I doubt this instance is applicable.

 

[Pete999]

From an electrical point of view it would be best to have a specific 16A radial circuit for the heater on a higher rated (16A+) plug and socket arrangement.
The rating of the immersion means that it is pulling the maximum current that a BS1363 socket should take so any slight anomalies may cause melting such as you have seen. The same thing happens with standard immersion heaters on plug and socket or fused spur arrangements.
With the circuit installation you have you are unable to avoid requiring a 13A fuse at some point, presumably the wifi socket may be fused, the plug in the wifi socket will be fused and in the current set up the plug on the outside is also fused.
Each fuse (and each connection) is a potential point of failure.
The wifi socket must also be close to its rated limit as they are often limited to 10A or even 5 A.
The simplest solution would be to have a 16A socket installed outside instead of the double socket and still plugged in as you have it now inside, however this will only transfer the possibility of failure to the wifi socket and the plug which is used inside and will not address the heavy loading on the ring, although if it is only used at night the loading on the ring will probably be low.

A bit long winded but Yes

 

[Ian1981]

I believe somewhere there is a requirement for immersions not to be on plug tops but I doubt this instance is applicable.

GN1 advises a plug and socket set up for connecting immersion heaters is not recommended id imagine due to the 13amp plug and fuse being subject to their maximum loading for lengthy periods of time daily.

I've also come across 13amp fused Spurs feeding immersion heaters on economy 7 installations during eicr s , where the spur shows signs if thermal damage and in some cases the spur has cracked across the plate but the fuse is still intact, all be it melted into the plastic holder.

 

[Dan White]

What does it show, when plugged into the socket without the Wi-Fi thing?

i.e. socket turned off?

With the socket turned off (I.e the wifi adaptor off) it shows no N. With it turned on it's all normal. I presumed it's how it works to keep the wifi signal active?

 

[telectrix]

@OP. if this appliance is in your van, does that mean that you plug it in at customers' premises. i.e. on site, as opposed to at home? if so, you would risk overloading their circuit/s. only solution would be to replace the heater with a lower power unit.

 

[Dan White]

@OP. if this appliance is in your van, does that mean that you plug it in at customers' premises. i.e. on site, as opposed to at home? if so, you would risk overloading their circuit/s. only solution would be to replace the heater with a lower power unit.

That's a good point. Usually I plug it in at home and turn it on for an hour before I leave. It general stays hot enough all day - so I don't need to plug it in.

But on occasion I do plug it in at customer's houses via my extension lead and have never had a problem. Although as the tank is already warm, I doubt it 'fires' for long before reaching the required temp.

The other guy who I work with has been doing this job for 13 years, and has used this set-up for all that time with no issues - except for the element blowing every three months or so (although that's probably more to do with the sodium hydroxide in the tank!)

So - would the best solution (given that there's is some debate about best practice) to run a dedicated feed from the CU out of the house and to a 16A rated socket with 16A plug?

As I need to plug it into the van would a 16A socket and plug (on the element) in the van also be required? I'm presuming so.

 

[Pete999]

That's a good point. Usually I plug it in at home and turn it on for an hour before I leave. It general stays hot enough all day - so I don't need to plug it in.

But on occasion I do plug it in at customer's houses via my extension lead and have never had a problem. Although as the tank is already warm, I doubt it 'fires' for long before reaching the required temp.

The other guy who I work with has been doing this job for 13 years, and has used this set-up for all that time with no issues - except for the element blowing every three months or so (although that's probably more to do with the sodium hydroxide in the tank!)

So - would the best solution (given that there's is some debate about best practice) to run a dedicated feed from the CU out of the house and to a 16A rated socket with 16A plug?

As I need to plug it into the van would a 16A socket and plug (on the element) in the van also be required? I'm presuming so.

I imagine you would need a circuit from your CU to a 16 Amp socket, your heater would require a 16 Amp plug top to enable you to plug it into the 16Amp socket wired from your CU how you would manage at the customer premises is a different problem.