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UMC Mains Extension cable

Jonslatt

Member
Aug 31, 2019
177
133
Malvern, UK
sounds like a good idea!

found out cable is 6m btw. Manual also says don’t use with extension cables

Main reason for not using extension cables is folks forget to unwind them fully. Induction generates heat in the windings which can be enough to cause a fire.

I have been using a 13A drum reel (fully unwound) for a number of years with a granny charger and had no problems.
 
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Roy W.

Battery running low...
Jun 3, 2019
2,334
2,393
Derby, UK
Tesla sell Schuko adaptors wired each way round, so a pair them might be prudent.
We’ve got a trip to France in the planning stage at the moment. Being an honorary Yorkshireman I’ve made up my own adapters to be able to switch live/neutral polarity.

A couple of rubber Schuko plugs and a couple of rubber sockets (£5.95 delivered from CPC) with a bit of 2.5mm cable I had in my odds & sods drawer :D

A black stripe on one cable denotes reverse polarity.

032CC845-7002-40ED-8CCA-3DE08345AE6E.jpeg
 
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Adopado

Active Member
Aug 19, 2019
4,270
3,232
Scotland
A couple of rubber Schuko plugs and a couple of rubber sockets (£5.95 delivered from CPC) with a bit of 2.5mm cable I had in my odds & sods drawer :D
View attachment 459209

I am noticing that there is a range of knowledge levels amongst those who post and read this information. Roy clearly knows what he's doing. Just for clarity, when Roy talks of 2.5mm cable he is referring to the size of the individual cores: live, neutral, earth, inside the cable. The outside diameter of the whole cable is a different thing and is not a reliable guide to how "heavy duty" a cable might be. You really need to know the size of the cable cores before buying a commercially produced cable for a charger extension. The words "heavy duty" are widely abused.
 
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Roy W.

Battery running low...
Jun 3, 2019
2,334
2,393
Derby, UK
I am noticing that there is a range of knowledge levels amongst those who post and read this information. Roy clearly knows what he's doing. Just for clarity, when Roy talks of 2.5mm cable he is referring to the size of the individual cores: live, neutral, earth, inside the cable. The outside diameter of the whole cable is a different thing and is not a reliable guide to how "heavy duty" a cable might be. You really need to know the size of the cable cores before buying a commercially produced cable for a charger extension. The words "heavy duty" are widely abused.
Right, I'm sorry, perhaps I should have included a health warning in the original post.

Certainly NOT something you should be doing unless you're comfortable with it. My dear departed Dad was an electrician, so I grew up with plugs and sockets :confused:
 

interbear

Member
May 27, 2019
726
631
Monmouthshire, UK
I saw these recommended on another thread and will be buying from them. Range here:
Electric vehicle leads

In terms of specifics, I’ll be buying one of these, the weatherproof element is important as is the inline RCD. Just need to work out the cable length required when visiting relatives in Scotland:
13A extension lead BMW, Tesla, Nissan & Jaguar compatible (RCD options)

Also travel to France a lot so need to invest in these for use at campsites or relatives homes out in the countryside and miles from superchargers :
European Schuko/French CEE 7/7 plug to 13A socket adaptor
Plus the reverse polarity version so I’m covered, no hassle to carry both:
Reverse polarity adaptor European Schuko/French 7/7 plug to 13A socket

I think - and hope - this lot should cover all scenarios I encounter.

If anyone that actually knows about his stuff would like to point out any flaws in my strategy, please do
 
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WannabeOwner

Well-Known Member
Nov 2, 2015
5,758
2,928
Suffolk, UK
European Schuko/French CEE 7/7 plug to 13A socket adaptor

On that site there is useful page Safely Charging your Electric Vehicle and amongst lots of useful advice has this:

"The 1.5mmsq vs 2.5mmsq flex debate seems to be the most common one with regards to EV leads on on-line forums, and sadly the most uniformed. For lengths of up to 20m, our advice is that the 1.5mmsq flex used in all of our leads is the best option for the following reasons ..."

They also have the option for waterproof socket on their adaptors / extension leads, and either an RCD plug or (e.g. where that will not fit an exterior socket) and in-line RCD
 

Jason71

Active Member
May 8, 2019
3,052
3,060
Shropshire
I am noticing that there is a range of knowledge levels amongst those who post and read this information. Roy clearly knows what he's doing. Just for clarity, when Roy talks of 2.5mm cable he is referring to the size of the individual cores: live, neutral, earth, inside the cable. The outside diameter of the whole cable is a different thing and is not a reliable guide to how "heavy duty" a cable might be. You really need to know the size of the cable cores before buying a commercially produced cable for a charger extension. The words "heavy duty" are widely abused.
In case anyone finds this post "like duh" I bought a couple of meters of 1.5mm grey solid core house wiring cable in Wilkos the other day. when I told the guy at the checkout it was 1.5mm to help him find the price he said
"wow you're the first person to be able to tell me that. normally when I ask people they are like 'I don't know it's just grey cable' ".
i was horrified. There are people buying mains house wiring cable who don't even know what size they are buying. What the hell are they doing with it!!!
 

TezzyMod3

Member
May 30, 2019
215
85
London
Your cable is 1.5 diameter. it will have 6M of Tesla cable on the end, so whether 1.5mm is sufficient for the overall length I don't know, but I deliberately bought "one size up" to avoid having an issue with combined length, and also for some extra redundancy / less heat generation.

plug looks rigid, rather than rubberised. Not sure if that matters.

Doesn't look like H07RN-F cable. H07RN-F is very tough, and cold resistant, so less likely to suffer from abuse if trailed along rough tarmac etc.



Possibly that is a different animal?

This one is 5M and £15.67 if you want 1.5mm or £18.67 if you want 2.5mm. Still isn't £10.99 though ...

5m single socket heavy duty 13amp black extension lead

No allegiance, I got mine from them and am happy with it

thanks for the advice. I bought one. With shipping and VAT it actually comes to 24.66. What’s £10 if I can sleep in peace. Also, as others have suggested, would be great for visiting people even after wall charger comes in.
 
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interbear

Member
May 27, 2019
726
631
Monmouthshire, UK
On that site there is useful page Safely Charging your Electric Vehicle and amongst lots of useful advice has this:

"The 1.5mmsq vs 2.5mmsq flex debate seems to be the most common one with regards to EV leads on on-line forums, and sadly the most uniformed. For lengths of up to 20m, our advice is that the 1.5mmsq flex used in all of our leads is the best option for the following reasons ..."

They also have the option for waterproof socket on their adaptors / extension leads, and either an RCD plug or (e.g. where that will not fit an exterior socket) and in-line RCD

I found it a good website, for the uninitiated (me), it provides plenty of good advice, one of the reasons I decided to order from them. Or will do when I need these cables.
 
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VanillaAir_UK

Well-Known Member
Jun 17, 2019
8,422
5,956
Surrey, UK
In the end I went with inline RCD version of this just to get us up and running. 13A extension lead BMW, Tesla, Nissan & Jaguar compatible (RCD options) I really liked the IP66 inline RCD and large socket and I think the smaller diameter cable will be easier to handle as I needed at least 12m so its quite a long run at 15m.

Commando yet to be installed and will be backup to TWC, so if position to meet UMC cannot be accommodated at time of install, I'll have to sort something then. That still gives me 32A option for commando should I decide. I wont really know until we get car and everything is all laid out. A 6m UMC and a 4.7m car is all potentially a bit tight of free cable when nose in.
 
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p_iv

Member
Jul 8, 2019
51
33
UK
Is it possible to put attach the blue type 2 cable to the output of the UMC and use that as an extension cable if needs be? As it's basically just an extension cable itself...
 

arg

Supporting Member
Supporting Member
Aug 22, 2012
1,815
1,816
Cambridge, UK
Is it possible to put attach the blue type 2 cable to the output of the UMC and use that as an extension cable if needs be? As it's basically just an extension cable itself...

No. This is deliberately arranged (by the design of the connectors) so that it doesn't work, to avoid various safety concerns.
 
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vitesse

Active Member
Apr 2, 2019
1,026
294
Hertfordshire (UK)
I am absolutely not an expert and other than testing it have never used my UMC in 2.5 years of ownership. However, I think I’ve read here that if using it via a 3 pin plug socket at 10 Amps it is wise to check the plug isn’t heating up. It’s related to these sockets not being designed for that level of draw for extended periods, so turning it down might be advisable.

@arg who be my go to or @WannabeOwner for knowledgable advice on this.

Absolutely; I used a 30 metre 13-amp rated (bog standard) extension cable when staying with a friend recently and all seemed fine until the extension cable was unplugged - the plug was extremely hot - too hot to handle actually. That was only an hour's worth of charging as well.
 
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vitesse

Active Member
Apr 2, 2019
1,026
294
Hertfordshire (UK)
So my install date for pod point is mid October. I was looking to use a standard 3 pin until then. Only problem is that it’ll be outdoors. Are these UMC things waterproof/resistant? I.e. can I leave under car?
Also, anyone know how long the cable actually is?
Because of problems with our wall point box (now resolved) I had to use the UMC daily, although this was from a 13A socket optionally built in to the (ROLEC) box and I wasn't using an extension cable. I was also concerned about rain so I taped cling film over the exposed bits! It certainly kept everything dry. I have been told since that the UMC is splash proof, but I don't see any rubber seals.
 

LukeT

Member
Apr 9, 2019
729
337
UK
My gen2 UMC is IP65 rated. Rubber sealed at the fixed cable entry. I'm not sure the proprietary black connector (what is that called?) is "sealed" exactly but the water has a long way to go to ingress there.
 

arg

Supporting Member
Supporting Member
Aug 22, 2012
1,815
1,816
Cambridge, UK
Absolutely; I used a 30 metre 13-amp rated (bog standard) extension cable when staying with a friend recently and all seemed fine until the extension cable was unplugged - the plug was extremely hot - too hot to handle actually. That was only an hour's worth of charging as well.

Yes, this is the common problem - the 13A plug/socket combination overheating. There's a number of sources of heat:
  • The fuse. Nothing you can do about this, as part of its basic function it is supposed to get hot as you approach full rating.
  • The cable. Will be hot if run at full rating, but if you go up a size so it isn't at full rating then it helps keep the rest cool.
  • The contacts inside the plug, particularly the fuse holder. One big problem with extension leads is that they are often made with "heavy duty" plugs - ie ones with slightly flexible cases so that if you drop them on the floor etc they don't get damaged. That's all very well, but it often means that after a while the plug goes slightly out of shape, spoiling the geometry of the fuse holder and so causing poor contact onto the ends of the fuse (of course, if it's a crappy one then the contacts could have been poor in the first place). Personally, I like to use the old MK plugs with hard bodies that can't go out of shape - but it's not a panacea, instead I have to keep an eye out for them getting cracked etc. knocking around in the toolbag.
  • The contacts in the socket. Not much you can do about the socket you are plugging your extension into, but old worn ones are a problem and the reason your otherwise-perfect extension will still sometimes overheat. The socket at the other end of your extension lead is also a potential problem, and the sort where the socket is built-in to the cable reel are often terrible - the plastic is chosen to suit its job as the reel and is far to flexible for the job of holding the contacts in position. For general-purpose extension leads I like to use metal-clad sockets (as sold for wall-mount use) adapted with a suitable gland and sealing the back box - but it's a trade-off and I hesitate to recommend it for EV charging. So a good cable-mount socket is probably the best bet.
  • RCDs. Unless your extension is being bought for a particular location where you know the circuit is already RCD protected, you really want an RCD. However the plug-top style of RCD is not great because a) it won't fit in many outdoor sockets, or you certainly won't get the lid closed over it, b) it adds to the overheating problems of the 13A plug to plonk an RCD on top of it. So I recommend in-line RCDs.

Reading the ToughLeads article seems like they think 1.5 beats 2.5 , I’m assuming therefore this should do a good job ?

13A weatherproof extension lead (RCD options)

I agree with them - the minimum size would be 1.25mm² and going up to 1.5mm² is enough for 10A charging unless the cable is enormously long. For an extension with 16A commando plugs/sockets (that you intend to use at 16A) there's more argument to go to 2.5mm². And if an enormously long cable actually is needed, I'd make it as a pair of short 13A-commando cables (using 1.5mm²) and then put a long commando to commando in the middle (that you can leave out when the full length isn't required).

As above, I'd recommend the in-line RCD, and I also strongly support their choice of H07RN-F cable.


Main reason for not using extension cables is folks forget to unwind them fully. Induction generates heat in the windings which can be enough to cause a fire.

It's not induction, it's just resistance heating that causes the problem. The resistance heating will be there regardless of whether the cable is wound up or not, but in free air the heat can escape, while wound up on a reel the heat just can't get out from the middle layers (which are covered by the other layers wound on top, themselves warm).

So overheating is a problem regardless of whether you make coils or just zigzags - if you cram them into a small space they will overheat. But if you've just got a short spare length lying there it doesn't matter that it happens to fall into a couple of loops. Better as a loose coil lying on the ground than (say) crammed tightly into a dribox. It's the extension leads that wind up onto reels that are the real problem.

The problem could theoretically occur with your type2 charging cable, but in practice they are normally built of one-size-above-minimum cable so they don't get that hot in the first place, and are stiff enough that you can't feasibly wind them up tight enough to matter.
 

VanillaAir_UK

Well-Known Member
Jun 17, 2019
8,422
5,956
Surrey, UK
Reading the ToughLeads article seems like they think 1.5 beats 2.5 , I’m assuming therefore this should do a good job ?

13A weatherproof extension lead (RCD options)

No you need the one with the bigger waterproof case 13A extension lead BMW, Tesla, Nissan & Jaguar compatible (RCD options) as apparently the Tesla plug wont fit in the one you linked to - someone else mentioned this problem too with Masterplug sockets. I also went with inline RCD and the separate circuit tester.
 

TezzyMod3

Member
May 30, 2019
215
85
London
FDA67A35-0E9F-4F31-A744-70ACBDCF14EB.jpeg
Right, cable came. Delivery on stamp said £5.50 so to be fair to them, it was more than I paid for it.

The quality is great. It’s the same thickness, weight and material as the UMC. I’ve put it in a dribox equivalent that looks more sturdy on amazon.

car is currently plugged in at 8A. Will check if heating, will push up to 10A in 1-2 hours. It’s in a plug directly under the fuseboard.
 
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