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Hello all
I have a Mercedes A250E PHEV it has a 3pin 13A plug to plug into the domestic ring main. I need to repair the 3 pin 13A end. There are 6 wires within the cable. does anyone have a wiring diagram to help with this
 

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Hello all
I have a Mercedes A250E PHEV it has a 3pin 13A plug to plug into the domestic ring main. I need to repair the 3 pin 13A end. There are 6 wires within the cable. does anyone have a wiring diagram to help with this
You need this thread...


The additional wires are for temperature sensors in the plug. There as a safety device to detect overheating due to the sustained high current draw.
 

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VW ID.3 1st Edition Manganese Grey - called Heidi Flowerpot
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Thanks for this, you've answered a question I've been asking for ages.

If you draw 10A for long periods through a 13A plugtop, the 13A fuse within is going to get at least warm considering that at 14A it's supposed to get so hot it melts and breaks the circuit. My question has been how warm will the fuse get and is it safe? If there are thermistors in the plug, I guess that ensures that the circuit won't get too hot. Good to know.
 

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Don't count your chickens too soon! Here's one socket I toasted at 10A, 13A plug + thermistors was quite happy to let it simmer!!! I now try as hard as poss to stick to 6A grannies!

143102
 

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You'll be surprised by fuse ratings, A 13 A fuse is rated to blow after 10 seconds at anything between 28A and 55A, in fact they are rated so they should never blow below 20A. Take a look at this link

Why a 13A fuse does not blow at 13A

The issue with 13A plugs is that the live cable can't take the heat away from the live pin as the fuse is in the way. As the pin is rectangular it's possible for it to have 2 small points of contact with the socket connector which is where the heat is usually generated. Using good quality sockets is a must if you are going to take out high currents for hours on end.
 

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And I don't think mit's helped by the L & N pins having their cross-sectional area reduced to accomodate the black insulation going half way down. I suspect that stopped the heat generated in the socket I cooked from travelling up into the plug & triggering a thermistor shutdown. Here's the closeup of the failed N & ok L clips from inside the socket: There really isn't much "spring" in this design at all!
143103
 

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Don't count your chickens too soon! Here's one socket I toasted at 10A, 13A plug + thermistors was quite happy to let it simmer!!! I now try as hard as poss to stick to 6A grannies!

View attachment 143102
Change it for one made by MK. MK double sockets are rated for continious 30 amps. I used one to charge a Chevy Volt @ 10amps every night for 2 years without and melting or browning.
 

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Change it for one made by MK. MK double sockets are rated for continious 30 amps. I used one to charge a Chevy Volt @ 10amps every night for 2 years without and melting or browning.
100% Agree with this. I permanently use MK sockets without them heating up beyond luke warm. A cheap socket at my parents can get quite warm after 8 hours of charging when I visit. Another thing I have found very useful for reassurance after horror stories on this forum is the use of a HUE Smart Plug, which has excellent diagnostic info and digital heat sensors. Also great for turning the charge on/off remotely!
 

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And I don't think mit's helped by the L & N pins having their cross-sectional area reduced to accomodate the black insulation going half way down. I suspect that stopped the heat generated in the socket I cooked from travelling up into the plug & triggering a thermistor shutdown. Here's the closeup of the failed N & ok L clips from inside the socket: There really isn't much "spring" in this design at all!
View attachment 143103
I found one of these plugs on a low power appliance where the mains had become intermittent. I threw it away as I concluded that it wasn't fit for purpose.
 

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Don't count your chickens too soon! Here's one socket I toasted at 10A, 13A plug + thermistors was quite happy to let it simmer!!! I now try as hard as poss to stick to 6A grannies!

View attachment 143102
Again, this is a very atypical failure as it appears to be on the neutral pin (unless the picture is reversed?). There was clearly something very wrong here.

It is worth pointing out that I've seen similar socket overheating and failure on a tumble dryer with an extension lead.
 

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Worst I've seen is on one of those old rubberised type extension sockets, presume from the 70s/80s. We had a dishwasher plugged into one for years and there was always this very faint burning smell. One night it just completely burned through, luckily didn't cause a fire or anything. But that was only a dishwasher which presumably only takes 10A for a few minutes, so must have been a very dodgy connection in the socket. Think they were MK sockets actually...
 

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There is a bit of history with MK as they used to be excellent then they dropped their standards and became pretty poor for a time when I think they may have manufactured the parts somewhere with poor quality standards. A few years ago MK improved and got back to where they used to be years ago. So depending on the age of the fittings you could have an older one that is very good a middlingly old one that might be not so good at all or a newer part that is close to being as good as the originals.

Worst fittings I have seen as far as UK/Irish sockets go are the no name ones sold in the DIY sheds for peanuts. Dodgy DIY electrics combined with junk fittings from a DIY shed has to be about the worst combination possible. At least with decent quality fittings a DIY job has half a chance of being OK.
 
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