Extension leads and commando

[LukeT]

Is there any concern about using the commando plug as a base for a 3-pin extension?

I realised I have some of the componentry already for this and some heavy duty cable which I put together ages ago for a specific powertool use which is no longer required, so with a little work and a neat reuse of stuff I could go from commando to "compact" letter-box plug on a long cable as per Xavelec then make up various ends from that - 3 pin, Schuko, adapter to reverse the Schuko, whatever, as needed. I think it would get very little use truth-be-told.

It strikes me that commando to commando would be a stronger/better protected connection outside than a 3-pin plugged into an extension.

Am I missing anything?

 

[arg]

Commando is definitely better in principle than ordinary 13A plug/socket, especially if you spring for the IP67 (waterproof) ones. Even if you don't, the heat generated by the fuse in a 13A plug is a source of problems best avoided.

However, this does then beg the question of what you use at the UMC end. If you use the three-phase (red) commando adapater on the UMC, and just wire one phase of it, that will work well for pure commando setups (automatically selecting 16A charge current in the car). However, that charge current is wrong if you are mostly charging from 13A sockets; the Tesla adapter isn't IP67 so although it will still work with a waterproof plug on your extension the seal won't have anything to mate with. Also, the red adapter is expensive if you don't otherwise need it.

Taking the existing 13A-plug adapter from the UMC, cutting off the plug and fitting a commando would be better in those respects; it would mean you are limited to slow 10A charging when there's a 16A commando available, but in many such cases (caravan supplies) actually taking 16A out of it is marginal and you are better off charging slowly than tripping the supply and annoying your neighbours.

Using the blue 32A commando adapter on the UMC is a bad idea as the car will default to 32A and so overload the 13A/schuko socket at the other end.

With all of these, putting an in-line RCD near the plug end of the extension cable is a good idea, as the RCD function in the UMC only protects the cable between UMC and car (this is why the 13A adapter is so short).

 

[LukeT]

Using the blue 32A commando adapter on the UMC is a bad idea as the car will default to 32A and so overload the 13A/schuko socket at the other end.

You are a fountain of knowledge! I've used 16A for a few things at home. I quite like the idea of just more solid hardware but I wasn't thinking of modifying the Tesla gear even by cutting off a plug because when I don't need an extension I assumed it'll be useful and safest as is.

So the choice of connection hardware at the UMC end of the extension cable is detected by the car/UMC and from that it chooses charging current? I'm going to sound stupid here but how does it detect a particular type of connection that's remote from it up the line? (Obviously, I am not an electrician!)

I was thinking to use the blue 32A plug purely on the basis that it's there and looks more resilient hardware for a simple extension connection and better able to take my thicker cable. But it sounds like I should just use 3-pin at that end and keep it in a box. I would in any case be making a lead to 13A at the house end. In-line RCD should be an easy addition.

 

[arg]

So the choice of connection hardware at the UMC end of the extension cable is detected by the car/UMC and from that it chooses charging current? I'm going to sound stupid here but how does it detect a particular type of connection that's remote from it up the line? (Obviously, I am not an electrician!)

It can't tell what plug is up the line.

The non-standard connector between the adapter pigtail and the main part of the UMC has an extra pin, and the adapters contain different values of resistor connected to that pin, so it knows which adapter you are using, and from that deduces what current to tell the car it can take. But it can't then tell what other kind of adapter/extension you have used beyond that - hence the instruction in the manual not to use extension leads.

 

[LukeT]

Ah! Interesting. Hence the choice to use a non-standard connector I guess. I don't own one yet so hadn't inspected it in detail.

Then I will use standard 3 pin stuff I think. I liked the Xavalec thinking but probably don't need a lot of the gear for very occasional 3 pin connection only.

 

[LukeT]

I am now told that my Model S will come with a UMC that includes 13A 3 pin and 16A small commando plugs. And that available from Tesla is the 32A plug which will enable 32A charging.

Therefore I could make up an extension lead based on the 16A commando plug, through a letterbox connector and an in-line RCD. All nice solid simple hardware, some of which I have already. This would be to work on the assumption that this will draw the same as the 3 pin plug, so 10A.

(@arg especially) Anyone aware of a reason I shouldn't do this?

 

[arg]

Sounds like the Model S is now coming with the V2 UMC first seen with the Model 3.

It will almost certainly draw 16A with the 16A commando adapter fitted - so taking that through extensions etc to a 13A plug isn’t totally ideal, but not an unreasonable thing to do. You will have to turn down the current at the car end, but accidentally taking 16A if you forget is less scary than 32A. OTOH, it does run the risk that you don’t notice (no fuse is going to blow any time soon), increasing the (small) chance of an unlucky sequence of events leading to overheating/fire.

Alternative would be to cut off the plug of the 13A adapter and use replace with letterbox friendly connector as the base of your extension lead setup, though of course that then leaves you with max 10A even if you have a commando socket as the source you are starting from.

 

[LukeT]

Sounds like the Model S is now coming with the V2 UMC first seen with the Model 3

I thought the new UMC was limited to 16A max regardless? They're telling me this one can take 32A. It wouldn't be a surprise to find the info is wrong but they seem to suggest either this is a new one or it's the V1 UMC modified to take a 16A option and then only supplying the 32A option as an extra. It'd be a shame to find the UMC is throttled to half the old one's max current even with a 32A plug on it, but not a big surprise. I don't suppose many have a 32A socket.

Alternative would be to cut off the plug of the 13A adapter and use replace with letterbox friendly connector as the base of your extension lead setup, though of course that then leaves you with max 10A even if you have a commando socket as the source you are starting from.

Now there's a plan. Realistically if I am running into someone else's house through an extension I need to keep it down to 10A, so safer if it's throttled automativally, and I think safer in this instance is better even if it's occasionally slower. So I think I'll do exactly this, with a compact to compact extension and a short compact to 3-pin via RCD on the house end. This way I also have better weather sealing since the compact to compact is IP68 rated. What is weather sealing like on the UMC itself? I don't recall it being designed to be left outside but it's probably better than a 3 pin plug and could be boxed alone (or with the proprietary connector) I guess quite easily.

For an RCD I assume you would use a 13A one?

If I found I was using 16A sockets and needing an extension I could make a new plug end up in no time.

Can this connector take the current over a long period?
16A Plug and Socket Cable Connector (3 pole) - IP68
The 1.5mm terminal capacity seems inadequate although I can't remember off-hand the cable size requirements. I thought I'd seen better. My googling today is weaker for some reason than when I found the products I thought I'd need some months ago...

 

[arg]

I thought the new UMC was limited to 16A max regardless? They're telling me this one can take 32A. It wouldn't be a surprise to find the info is wrong but they seem to suggest either this is a new one or it's the V1 UMC modified to take a 16A option and then only supplying the 32A option as an extra. It'd be a shame to find the UMC is throttled to half the old one's max current even with a 32A plug on it, but not a big surprise. I don't suppose many have a 32A socket.

Accurate data has been hard to come by, but I think the new UMC is 32A-capable but only single phase and supplied by default with the 16A commando plug. Single phase to save money, maybe 16A because many continental homes can't manage 32A on one phase (which was why the old UMC supported 3-phase).

What is weather sealing like on the UMC itself? I don't recall it being designed to be left outside but it's probably better than a 3 pin plug and could be boxed alone (or with the proprietary connector) I guess quite easily.

Yes, that's my assessment - the UMC is not sealed around the interface between adapter and UMC proper, so needs some measure of weather protection, but that's easier to do (without causing overheating concern) than a 13A plug/socket combo.

For an RCD I assume you would use a 13A one?

I'd go with an in-line one, not a plugtop one, because the plugtop ones exacerbate heating issues from the fuse and also are larger than a standard 13A plug so often won't fit in outdoor-style 13A sockets (or other sockets that have been installed stupidly).

Given what you are now planning to build, you only need a 13A rating, but in fact the in-line ones are usually 16A rated anyhow.

Can this connector take the current over a long period?
16A Plug and Socket Cable Connector (3 pole) - IP68
The 1.5mm terminal capacity seems inadequate although I can't remember off-hand the cable size requirements. I thought I'd seen better. My googling today is weaker for some reason than when I found the products I thought I'd need some months ago...

I bought a couple of those but was a bit disappointed when I got them and haven't actually put them into use. My main concern was that they come apart too easily and the contacts are not then well protected - I wouldn't want to leave them anywhere kids could come up and mess with them. In a controlled professional environment they'd probably be OK.

1.5mm² is adequate for this job unless you are making one enormously long - 1.5mm² is 16A rated, so headroom in hand at 10A.

H07RN-F cable type much preferred over alternatives such as the mis-named "arctic".

 

[LukeT]

Accurate data has been hard to come by, but I think the new UMC is 32A-capable but only single phase and supplied by default with the 16A commando plug. Single phase to save money, maybe 16A because many continental homes can't manage 32A on one phase (which was why the old UMC supported 3-phase).

Thanks @arg. You are a huge help on all these things.

If that's the case then I'm happy. And it tallies with what Tesla said. I'll confirm either way once I try it. Long term (once I've a proper home charge point), if I'm using the UMC I figure I'm not on three phase unless I'm in fairly unusual situations and the overnight 10/16/32 amps single phase will do what I the UMC is for. So keeping single phase 32A but losing three phase on the UMC wouldn't concern me.

I'd go with an in-line one, not a plugtop one

Given what you are now planning to build, you only need a 13A rating, but in fact the in-line ones are usually 16A rated anyhow.

In-line was my plan. No concern then in fitting one that accepts a higher current (16A, there are inline 13A ones available but the quality could be less good) than other elements of my system (13A plug)?

I bought a couple of those but was a bit disappointed when I got them and haven't actually put them into use. My main concern was that they come apart too easily and the contacts are not then well protected - I wouldn't want to leave them anywhere kids could come up and mess with them. In a controlled professional environment they'd probably be OK.

1.5mm² is adequate for this job unless you are making one enormously long - 1.5mm² is 16A rated, so headroom in hand at 10A.

H07RN-F cable type much preferred over alternatives such as the mis-named "arctic".

Then I think I will press on. For now. They don't look brilliant, those connectors, but so long as they're up to the current I'll work on the basis they're for occasional use and I can replace them if I find better. Hard to see the contacts properly online though.

 

[arg]

In-line was my plan. No concern then in fitting one that accepts a higher current (16A, there are inline 13A ones available but the quality could be less good) than other elements of my system (13A plug)?

Current rating in amps on RCDs is a withstand rating, so the bigger the better. RCDs don't open at their withstand rating, you are relying on the fuse in the plug for overcurrent protection.

The sensitivity of an RCD is specified in mA (normally 30mA).

There's also Type-AC/A/B, but for the sort of device we are talking about you can probably only find Type-AC, and that's OK for this job as the extra RCD is only there to protect the extension cable against mechanical damage; the RCD function within the UMC should protect against faults in the car that could be more exotic.

 

[LukeT]

Had some H07RN-F 2.5mm2 so made this up. Will replace umc 3 pin socket with the compact connector then that can go to the 3 pin through the rcd with or without the extension. About 17m long. I may shorten it if I find its over the top once I've strung it out in a couple of driveways. May also look to replace the blue cable with some of the big stuff but I can't see it being an easy fit.

I don't currently have a box to house the umc but I'll wait til I get that to consider my options. Anyone found a dry box that neatly houses that and the proprietary connector (which I assume also isn't outdoors IP rated) alone? I'm wondering if I'd get away with a smaller one than the Dribox 330 folk use to house umc plus all the connections. Then again, it'll live with the extension in anyway when not in use so space may be a non-issue.

Perhaps something like this (orange and sturdy seems sensible) might work:
https://www.amazon.co.uk/gp/product/B00NNQYVDK

Picking up my car and heading off on a bit of a road trip the next day, also with a mucky mountain bike and dog so it'll be interesting to see how they work with one day old white seats.....

 

[LukeT]

I didn't cut my UMC cable to fit the compact connector. I just put the 3 pin in the box. Perhaps a slightly less good solution for extension but it leaves the UMC as supplied for the rest of the time.

I used a pretty basic trailing socket instead. Ideally I'd replace this with a heavier duty one to take thick cable.