Long Gardens and extentions

[phillcom3]

My pearants house has a very long drive and then a very long path before the house. What's the longest safe extention for the granny cable as I realy don't want to take the car up their drive its to thin. Somthing will be in the hedge knowing my dad and it will scratch.

To add they are 100 miles away and the nearest charger is at an IKEA.

 

[NewbieT]

Define ‘long’!

Firstly, Tesla official advice is not to use any extension cable at all with the UMC.

Many people including myself do use say 20m extension plus the UMC which is 6m.

Safety: use an RCD. The voltage will drop the further you go and do you then need larger cable cores.

 

[Cwmwd]

If you're looking for an extension cable I can recommend the EV extension cables from Tough Cables with the in-line RCD and waterproof box on the end.

Electric vehicle leads

But, if we're talking 100s of meters then you might be better off canvassing the neighbours on PlugShare or treat your folks to a night out at the local pub with a 16A commando outside...

 

[Glan gluaisne]

The main thing (apart from the obvious stuff like safe routing of the cable, weather tightness, etc) is the voltage drop. If possible, try and get a tough cable made up from 2.5mm² H07RN-F. The maximum acceptable voltage drop is about 5% at full load, and a 50m run of 2.5mm² H07RN-F will have a drop of about 3.9% at 10 A, so acceptable.

2.5mm² is about the very largest cable that can be terminated in a 13 A plug, and even then it's a real struggle, as plugs are not really made to take this size of cable (can be done, though).

The largest cable that Tough Leads make is a 25m one, that uses 1.5mm² H07RN-F cable. You couldn't, for example, use a 50m long cable made from 1.5mm² cable as the voltage drop would be too high, around 6.5% at 10 A.

Making up a long, tough, extension lead is not hard, although the ones Tough Leads sell are good value if you are OK with up to 25m long. If you wanted a longer cable, then 2.5mm² H07RN-F is around £1/m. Probably the easiest way to terminate such a cable (given that it doesn't fit easily into a 13 A plug) would be to get a pair of 16 A free commando connector (plug for the lead, plus another free socket) and then make up a short adapter lead from 1.5mm² cable with a 13 A plug on one end and the commando socket on the other. For the other end of the 2.5mm² cable, then a B&G weatherproof single outlet can be fitted, with a suitable screw type cable gland for the cable inlet.

I have a 25m extension lead like this, plus another 25m extension lead (made from 2.5mm² cable) that has 16 A commando connectors on either end. This gives me several options, as I can charge from a 16 A commando outlet, or a normal 13 A outlet, at some distance from the car. I also fitted an RCD plug on the short adapter cable. Not shown in this photo is the additional extension lead that just has a commando on either end:

 

[Roy W.]

Depending how often you see your parents you could also consider paying for a commando socket to be professionally installed near where you want to park on their drive. This would be safer, more elegant, and you won’t have to coil up metres and metres of wet cable in the rain.

 

[Joelly]

The main thing (apart from the obvious stuff like safe routing of the cable, weather tightness, etc) is the voltage drop. If possible, try and get a tough cable made up from 2.5mm² H07RN-F. The maximum acceptable voltage drop is about 5% at full load, and a 50m run of 2.5mm² H07RN-F will have a drop of about 3.9% at 10 A, so acceptable.

2.5mm² is about the very largest cable that can be terminated in a 13 A plug, and even then it's a real struggle, as plugs are not really made to take this size of cable (can be done, though).

The largest cable that Tough Leads make is a 25m one, that uses 1.5mm² H07RN-F cable. You couldn't, for example, use a 50m long cable made from 1.5mm² cable as the voltage drop would be too high, around 6.5% at 10 A.

Making up a long, tough, extension lead is not hard, although the ones Tough Leads sell are good value if you are OK with up to 25m long. If you wanted a longer cable, then 2.5mm² H07RN-F is around £1/m. Probably the easiest way to terminate such a cable (given that it doesn't fit easily into a 13 A plug) would be to get a pair of 16 A free commando connector (plug for the lead, plus another free socket) and then make up a short adapter lead from 1.5mm² cable with a 13 A plug on one end and the commando socket on the other. For the other end of the 2.5mm² cable, then a B&G weatherproof single outlet can be fitted, with a suitable screw type cable gland for the cable inlet.

I have a 25m extension lead like this, plus another 25m extension lead (made from 2.5mm² cable) that has 16 A commando connectors on either end. This gives me several options, as I can charge from a 16 A commando outlet, or a normal 13 A outlet, at some distance from the car. I also fitted an RCD plug on the short adapter cable. Not shown in this photo is the additional extension lead that just has a commando on either end:

View attachment 489142

Hi, thanks for the informative post. I am looking to buy one off the shelf and I just wanted to clarify about the 1.5mm 25m.
Are you saying that it is OK but could/should be better, are are you saying that it is perfectly up to the job and it’s as good as 2mm for example at that length?

 

[Glan gluaisne]

Hi, thanks for the informative post. I am looking to buy one off the shelf and I just wanted to clarify about the 1.5mm 25m.
Are you saying that it is OK but could/should be better, are are you saying that it is perfectly up to the job and it’s as good as 2mm for example at that length?

1.5mm² is fine at 25m, and is probably the reason that Tough Leads only make cables up to this length. The next cable size up is 2.5mm³. and whilst fine for longer lengths, it doesn't fit into a 13 A plug easily (strictly speaking, 13 A plugs are not supposed to be used with heavy duty cable this thick).

At the prices Tough Leads charge it would be hard to make a lead up more cheaply from the various bits, anyway, so they are pretty good value.

 

[Jason71]

I bought from these guys: Industrial Extension Leads Maximum extension lead length
Not saying they are the best or cheapest but they do have some interestng detailed info on maximum lead lengths for different cross sections etc.

 

[Compuguide]

I bought from these guys: Industrial Extension Leads Maximum extension lead length.

Ditto
Very happy with my 25m cable
Pretty good charge efficiency:-

 

[Adopado]

2.5mm² is about the very largest cable that can be terminated in a 13 A plug, and even then it's a real struggle, as plugs are not really made to take this size of cable (can be done, though).

Yes, I've done a 13amp plug with 2.5 cores ... very snug ... quite satisfying when you have the lengths spot on and get a perfect fit! (I have a lovely long cable that is only normally used for connecting a generator in the shed to temporarily run the house during power cuts ... but it rarely needs to be used for that purpose these days so I made up short 13amp plug/commando and 13amp socket/commando adapters for each end so I can also use the cable as a heavy duty 25m extension.)

 

[tsh2]

Ditto
Very happy with my 25m cable
Pretty good charge efficiency:-
View attachment 489155

I don't think this takes account of the cable loss, but it should be easy to calculate if you measure the voltage drop.

 

[Glan gluaisne]

I don't think this takes account of the cable loss, but it should be easy to calculate if you measure the voltage drop.

As a guide, a 25m extension lead, like the Tough Leads one, that uses 1.5mm² H07RN-F cable, should lose about 66.5 W at the 10 A that the Tesla UMC normally charges at with the 13 A plug adapter fitted. Assuming a nominal voltage at the car of 230 VAC, then that equates to a power loss of about 2.89% from the extension lead. There will probably be around another 10% loss within the car OBC, so overall the charging loss from those elements will be around 13%.

Using a 2.5mm² extension lead, like the one I've made up, reduces the loss in the lead to around 39.9 W, or about 1.735% for a 10 A charge current.

 

[LukeT]

I've made one up with 2.5mm too, but I took my cable into a low profile 16a letterbox connector both ends, which is sized to take the thicker cable. It's also ip rated and, of course, fits through a letterbox, so has other advantages that might be useful to you.

Extension leads and commando

 

[ringi]

I've made one up with 2.5mm too, but I took my cable into a low profile 16a letterbox connector both ends, which is sized to take the thicker cable. It's also ip rated and, of course, fits through a letterbox, so has other advantages that might be useful to you.

Extension leads and commando

Can you post a link to these letter box connectors.

 

[Glan gluaisne]

Possibly these: Elkay Ip68 Aquasafe 16A Connect 12-16mm (185-9200) | CEF

 

[LukeT]

Can you post a link to these letter box connectors.

Sure. I bought these:

https://www.amazon.co.uk/gp/product/B076QH9VF4

On first glance they're not the toughest thing in the world but so far I have not had a problem with them and they do appear to be a convenient solution. I am hoping to replace the 3-pin plug on a spare tesla adapter with one of these, which will complete this job with entirely IP rated parts, do away with the dribox and some thin cable and make it a bit more flexible. I think this will work but am not 100% certain. I'll post an update on that other thread if it does.

Possibly these: Elkay Ip68 Aquasafe 16A Connect 12-16mm (185-9200) | CEF

Jeremy's might be better/tougher though - pretty sure mine wouldn't take 4mm cable, plus the "snap lock" connection may be more convenient than my threaded one? Anyway, it's a product for the same job.

 

[UrbanSplash]

I don’t know what I would do without this forum...

is this suitable for the model 3 13a plug?

13A weatherproof extension lead (RCD options)

No idea which rcd? Plug or inline?

thanks all

 

[Glan gluaisne]

I don’t know what I would do without this forum...

is this suitable for the model 3 13a plug?

13A weatherproof extension lead (RCD options)

No idea which rcd? Plug or inline?

thanks all

Yes, should be if it's the larger one. The Tough Leads outlets are one of the few that are big enough under the cover to take the larger than normal plug that many granny leads have. The cable from the granny lead plug will be a tight fit when closing the cover down, though, just because it's a bit chunky, but it should close OK with a firm push.

The RCD type might be better for general use, where you don't know whether the circuit you're plugging in to is RCD protected. You may end up with two RCDs in series, if the circuit is RCD protected already, but there's no real problem with this for a portable appliance like this, as this arrangement is only really undesirable for a fixed wiring installation.

 

[MrBadger]

No, thats not suitable.

You need the larger version

13A extension lead BMW, Tesla, Nissan & Jaguar compatible (RCD options)

As for RCD plug or inline, thats personal circumstances. But if you ever think you need to plug into a weather resistant socket, you will probably want the inline version.

Also worth considering the test plug, but I cannot find it on website anymore. That can live plugged inside the above socket to check the electrics you hooked up to are reasonably sound. Then once it checks out ok, just swap over for the UMC plug.

 

[UrbanSplash]

Got the larger one. Thanks all!