We've been using a granny cable for 18 months now, but it's on a separate new spur and a RCD (residual current detector). Doesn't get warm at all. Older wiring etc may well cause problems. If granny's were dangerous they wouldn't be available, but it does depend on the home end.
Like all electrical appliances, they are only dangerous if they are used incorrectly or used in a manner that they where not intended to be used by the manufacture, or by running them on an electrical circuit that is not fit for purpose.
If you are pulling 2 Kw’s via a standard three pin plug, then some radiant heat at the plug top is going to happen, fact !.
Even if your electrics are 100% tip top, some small amount of heat will be present at the three pin plug after a while.
This is the same with any small appliances that pull higher load, for a shorter period of time as well.
If you have a high wattage hair dryer or a high wattage electric iron etc.
When the appliances has been running for a while ( drying somebodies long hair for example ) when you switch off the dryer and pull out the plug from the socket outlet, there WILL be heat present at the plug top or the line ( live ) pin of the three pin plug.
Fast boil kettles are the same, but the load is short and sharp.
A Granny cable is pulling 2 Kw’s over a much long period of time, this is when the heat is generated.
If your SOC was low on your EV when you commenced the charge, then it is very likely that the unit, will be running for a good number of hours.
I have nothing against using a Granny cables, I used one myself for 7 months before getting my wall box installed.
I myself also had a dedicated circuit with RCD protection and only ever used this socket outlet to charge the car.
The car was a VW PHEV at the time, from a low state of charge, it would take almost four hours to charge the small pack to full.
When removing the plug straight after the charge was completed, the plug back and the live pin of the plug was warm to the touch.
The very same thing happened in three different locations, when charging from a domestic supply.
It’s purely down to the that high load being drawn over a longer period of time.
The very same thing happens when using a wall box at home.
High load being pulled over a long period of time, therefore heat well be generated.
The difference here is that the wall box is a purpose built standalone unit, with upgraded wiring and accessories that will carry that additional load for longer periods of time, at a much faster rate.
Domestic plugs are rated to carry 13 Amps.
It is stamped on all three pin plugs and are likely to be fitted with a 13 Amp fuse as standard.
Will it take 13 Amps - Yes BUT it was never intended to be used for pulling that type of load over that long time frame.
They are all rated the same, but we all know that some are better made than others.
Side note ? How many people run every appliance in their house with the supplied 13 Amp in line fuse installed ???.
Well on a low powered and sensitive piece of tech equipment, if you are expecting the fuse to fail before the equipment, then it clearly not going to happen !.
Hands up :- How many people are still running tables lamp etc on a standers 13 Amp fuse ?.
This is massively over rated and if a fault in the flex developed, then it is likely to almost go on fire before the fuse fails.
Some owners who have larger packs and want to take full advantage of any “Off - Peak” tariffs, are likely to favour a wall box, purely down to the speed that it can charge.
If you are on a 4 - 5 hour cheap rate tariff, you want to maximise as much of that in charging time.
A Granny is no use for this purpose, it’s charging rate is too slow.
evonestop.co.uk
