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I've had an electrician install some new wiring for me for our new electric car charger. It is 10mm twin and earth. He's had to join two of these together, he hasn't fully finished yet, but I'm wondering if the join he has made is sufficient. I've attached a photo of his work.

The join is inside a void under our stairs behind some plasterboard. It will be taking a current of 16A for approximately 9 hours at a time. In the future our new car will be taking 30A. I'm a little concerned that this tape job isn't right. Any advice would be great. pic

Edit: Here is picture without the tape enter image description here

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    Can you please specify where this is? Based on the wire colors, I am guessing the UK. "10mm twin" isn't a phrase I've heard in the US, so specifying a location is important for understanding local codes and regulations. That said, I'm surprised to see this work outside an electrical box and just straight spliced instead of twisted in a wire nut. – Hari Ganti Mar 21 '17 at 20:47
  • Yes sorry didn't think of that, it's in the UK twin and earth is standard electrical cables used for wiring in houses. Here's a picture google.co.uk/…: – Adam B Mar 21 '17 at 20:51
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    10mm refers to the cross section, but that's not my question, 10mm was stipulated by the charge point installers due to the longish distance the cable covers. My question is, can you just crimp and tape cables like this when such high currents are involved and is it safe / legal – Adam B Mar 21 '17 at 21:48
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    That being the trouble with taped splices. Rather hard to inspect. @HariGanti the expression is "twin and earth" meaning x/2 Romex. – Harper - Reinstate Monica Mar 21 '17 at 23:06
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    The normal connection in the UK is a set screw type, not a crimp. You must join these wires according to your local electric code so contact the proper authorities. – Jim Stewart Mar 21 '17 at 23:10
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I've never seen a qualified electrician leave twisted and taped up wires in 30 years on the job. And that is because it is a ridiculous way to form a connection. The tape will degrade over time and turn into a sticky mess. Put the connection into a proper junction box rated for the job, they cost pennies.

p.s. I could nearly live with it, if the wires were soldered and then the whole thing put into a box, but even then the tape won't last forever.

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  • Thanks, are you an electrician? Do you know which kind of box is necessary for a 30A cable – Adam B Mar 22 '17 at 11:03
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    @AdamB Search for "30A junction box". £1.55 for a heavy-duty one from Screwfix. The silly thing is that it would have been quicker to use a junction box than twist and tape the wires. – Andrew Morton Mar 22 '17 at 14:19
  • Those junction boxes won't fit 10mm cable through them. – Adam B Mar 22 '17 at 21:16
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    @AdamB You (or rather your electrician) can make the holes in the junction box bigger. Or use could ask him/her about using Wago connectors, which also have boxes available to fit them in tidily. – Andrew Morton Mar 23 '17 at 10:48
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    @AdamB just google 60A or 60 Amp junction box. We use these to extend shower or cooker cables occasionally if it's not possible to swap the whole cable (just ensure good access afterwards though, never bury these in the wall etc.). Alternatively get a 60a domestic switch/ fuse unit or small fuse board (better but more expensive but also the option to isolate...). – handyman Mar 23 '17 at 12:19
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Ultimately if you're not happy then ask the electrician what other options you have. Personally (I'm not a professional) It looks a mess and there should be a junction box you can use to make that look a lot better. But don't be afraid to question what other options you have.

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AFIK normally one uses a receptacle in a box for supplying power to recharge an electric vehicle. The vehicle charger plugs into that receptacle. The receptacle and the plug will be rated for the current that the charger draws. The boxes are not rated for current, but must be of sufficient size to meet the fill limit given the wires and the receptacle. In practice, I would bet that a sufficiently deep box would meet the requirements and would fit in the existing hole in your wall. But if you would need a larger box, then enlarging the hole would be simple.

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  • Thanks, this is getting ahead though. The charger is being installed separately at a later date. At the minute we are just installing cabling to get power to the garage from the house. – Adam B Mar 22 '17 at 13:14
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    Is the garage attached to the house? Was the cable you have spliced to connected to a receptacle in a box at that location? Where is this hole, in the garage wall or in a wall in the house? You have spliced a cable that goes out of the wall. Where is that cable intended to go? Is it going to be surface mounted (in a code approved covered track) on the interior of the garage wall? – Jim Stewart Mar 22 '17 at 13:26
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    @JimStewart A receptacle is only used for portable EVSEs. Many people opt for fixed EVSEs because they tend to offer greater power for the same price, in which case you can either get them in plugged or hardwired variants. – Hari Ganti Mar 22 '17 at 20:12
  • Hari, thanks for informing me about this. So would this crimp splice be be allowed if it were coiled up in a box? And would there be a cover plate with a hole in the middle which the spliced cable would pass through? And would this cable be energized all the way to the end, at all times? – Jim Stewart Mar 23 '17 at 9:00
  • Would the cable for a fixed EVSE be stranded so that it is flexible? – Jim Stewart Mar 23 '17 at 9:18

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