Didn't think you were supposed to use an extension lead? Maybe an extra thick one that isn't too long - doesn't it get a bit hot? Everytime I've used my Mitsubishi 3-pin charger the three pin plug seems to get quite hot to the touch. Don't know how hot it's supposed to get?
Fortunately I now have a Rolec 32amp charger installed in my garage (my PHEV only actually sucks 16amps but thought 32amps might be handy in the future, the car decides how many amps to suck so 32 isn't a problem) which does indeed make life a lot easier. Wasn't that easy to achieve though as my garage is 20 meters (as the crow might fly) from my consumer unit (such as it is). The whole installation was supervised by Charged EV of Chesterfield. I laid around 15 metres of 6mm twin-and-earth cable from the consumer unit, under my floorboards with all the other cables, and then out through an outside wall.
Then I ran another 15 metres of 6mm armoured cable under my gravel yard to the garage. This had to be laid in a 600mm deep trench, with the cable laid on sand (half a ton), and with yellow plastic CAUTION! tape 150mm below the surface. This is to comply with Part 4 building regulations. Fortunately my neighbour has a mini digger. Charged EV then connected the Rolec on the garage wall (I provided a 12mm thick MDF sheet for them to attach it to), connected the twin-and-earth to the armoured cable on the outside wall via a suitable outside connector box, and then connected the twin-and-earth via a dedicated 32mp 'mini' (well, not that 'mini' - 300mm height by 140mm width) consumer unit to the mains meter in my house. Fortunately the wall unit that contains all my mains gubbins was big enough to fit it all in after a few bits were moved slightly. The 'mini' consumer unit had to be used a I only have old fashioned brown fuses which are not suitable for connecting to. Then it was all tested and switched-on.
Cost: Rolec 32amp charger £129, mini consumer unit £50, and fitting of both = total £179 (Charged EV). Type 2 to type 1 (7-pin to 5-pin) 5 metre connector £155 (Charged EV). 25 metres 6mm twin-and-earth cable (Screwfix) £34, 25 meters 6mm armoured cable (Quickbit.co.uk) £59. 20 metres CAUTION! tape £4.00 (ebay). Plus about two days of my time and some hefty digging (couldn't have done this without mini-digger) to lay the cables. Total cost for the lot = £431. So quite expensive then. Although if I'd paid electricians to do all of it, it would have been well over £1000.
As most of my journeys are less than 30 miles it does pay me to charge-up, and 3.5 hours is often more convenient than 5. I guess I could have just had a dedicated 13amp socket put in, but as my existing garage power supply is a bit old and slightly dubious, I would still have had to do most of the above.
I have suspended the 5 metre connector cable from my garage roof on rubber loops so I don't fall over it when I walk past the car when it's plugged in.
Were Charged EV any good? Well they answered my numerous communications promptly via phone and email and turned up when they said they would. They have supplied me with a part 4 and 7 Building Regulations Compliance Certificate. Considering the complex nature of my install and the fact that I was doing quite a lot of it myself they (mostly) kept up. Some of the finer details were a bit garbled but on the whole they were fine. I sent a message enquiry to Chargemaster via their website, but never got a reply.