UK 3kw constant load on a standard plug socket

[velocio]

I'm charging a PHEV from a standard plug socket, and it works. However I purchased an extension and the standard plug going into the socket has melted... it got a bit too warm for a bit too long.

Are there recommendations of specific plugs and cabling that could take 3kw comfortably for constant load?

The extension cable I have is 25m in length as I may not be fortunate to have my car parked directly outside the property.

 

[Mikegh]

I would say 3kw constant load will always cause problems

 

[Mikegh]

About 10amps max for a constant load imo

 

[brianmoooore]

Are you sure your vehicle charges at 3kW? Most chargers that plug in to a standard 13A socket limit the charge current to 10A.
Extension cables rated for the full 13Aare few and far between, and even these will show signs of thermal deterioration if used at full load for long periods.
If the car really does draw 3kW, you may be better looking for 16A plugs, sockets and 2.5mm2 flex.

 

[Pete999]

I'm charging a PHEV from a standard plug socket, and it works. However I purchased an extension and the standard plug going into the socket has melted... it got a bit too warm for a bit too long.

Are there recommendations of specific plugs and cabling that could take 3kw comfortably for constant load?

The extension cable I have is 25m in length as I may not be fortunate to have my car parked directly outside the property.

BS 7671 gives a recommendation that any load of 2KW and above should be on a dedicated circuit forv this very reason, tin hat on

 

[velocio]

Are you sure your vehicle charges at 3kW? Most chargers that plug in to a standard 13A socket limit the charge current to 10A.
Extension cables rated for the full 13Aare few and far between, and even these will show signs of thermal deterioration if used at full load for long periods.
If the car really does draw 3kW, you may be better looking for 16A plugs, sockets and 2.5mm2 flex.

Smart meter shows it draws around 2.7kw by itself.

The extension I use is presently this:

• 13 AMP 240V 3 Pin Black Plug
• 1.5mm 3183Y Orange Flex Cable

Though I'd note the plug has melted.

 

[velocio]

BS 7671 gives a recommendation that any load of 2KW and above should be on a dedicated circuit forv this very reason, tin hat on

This is definitely the thing now on my mind.

 

[Pete999]

This is definitely the thing now on my mind.

Cable and OCPD will need to be sized accordingly.

 

[littlespark]

I recently sat the NICEIC vehicle charging course, and plugging the car into a 13A socket is on its way out as a standard, but they did say that if it was done, the socket would be on its own circuit AND be specially designed and labelled to be suitable for car charging.

Standard sockets can’t cope with a constant 3kW load, never mind the plug.

 

[Lucien Nunes]

You need to have both a good plug and a good socket. If either is in any way substandard, a meltdown is likely. Historically, 3kW heaters were relatively common and 13A plugs were intended to supply them for hours on end. If you have not tried an original MK 646 plug in an original 2747 socket (or equivalents) you might be surprised as to how well they do handle a constant 13A load. But few are engineered that well these days and we have come to accept that 13A is a push.

This company appears to have addressed the problem of inadequate extension leads for EV charging:

EV granny charger 13A weatherproof extension lead

High quality 13A weatherproof outdoor waterproof extension leads heavy duty 1.5mm H07RN-F rubber cable. RCD option. IP66. Designed specifically to overcome the issue created by chunkier plugs on electric vehicles (EVs). 2m, 5m, 10m, 15m, 20m and 25m lengths.

toughleads.co.uk

 

[littlespark]

It was described to me that a heating 3kW load would cycle on and off with the thermostat... whereas a vehicle charger could be 3kW for a prolonged period

 

[Lucien Nunes]

Although for the first 20 years of 13A plugs, not many heaters had thermostats. I agree that the constant load of the charger is unusual but it was within the original design intent of BS1363 to handle 13A without damage.

I recall at dad's shop there were sometimes two 3kW non-thermostatic heaters plugged into one double socket running all day long in winter, because the installed heating system did not heat the centre of the showroom sufficiently. The socket ran warm but survived for years.

 

[littlespark]

They would be built to last back then

 

[pc1966]

Too some degree it is just a sad reflection of modern "value engineered" products that can't actually handle their rating under any sort of real-world use.

For 13A use then try a single socket (not double) from one of the better suppliers such as MK (but not the crap "essentials" range) or Schneider. For extension lead the problem is not the 1.5mm cable but the quality of the plug, so the same applies.

Also it can help to operate the socket's switch a few times before plugging in, and to plug in/remove a couple of times with the switch off before finally switching on. Reduces contact resistance slightly.