[flemming]

I was going to get a charger installed by Octopus until they changed their minds due to the locations of the meter and my driveway - they were insisting on installing a fat and very visible cable across the front of the house because the meter is on the opposite side of the house to the driveway (thanks to Barratt homes not having the damn foresight to put the meter on the side of the house next to my own land).

so, long story short... There's a fast charger I can use just half a mile away but for extra convenience, I'd like to be able to charge the car at home from a 3-pin plug in my garage. Is this a bad idea?

 

[Aleras]

As a permanent charging solution used regularly its a very bad idea....

 

[Harry6]

I was going to get a charger installed by Octopus until they changed their minds due to the locations of the meter and my driveway - they were insisting on installing a fat and very visible cable across the front of the house because the meter is on the opposite side of the house to the driveway (thanks to Barratt homes not having the damn foresight to put the meter on the side of the house next to my own land).

so, long story short... There's a fast charger I can use just half a mile away but for extra convenience, I'd like to be able to charge the car at home from a 3-pin plug in my garage. Is this a bad idea?

Hi, are you able to reduce the charge current down from 10A to 6A or 8A?
If you install a dedicated waterproof socket fed from an RCBO with PEN protection then you should be fine.

 

[Aleras]

Granny chargers are not meant to be used as a long term charging solution used regularly for hours at a time. You are right at limits of a three pin plug. Anything suboptimal this is what can happen.

There are numerous examples of fires started using these things. Get a proper charger Installed trunk the cable mask it etc. I have mine clipped to brick work around front of house although mainly obscured with landscaping. It is what it is.

It will cost a fortune charging on public chargers and very inconvenient. You need a proper home charger correctly installed with appropriate TOU tariff.

They are not intended to be used as a long term charging solution.

 

[idiotzoo]

The problem is the UK mains plug. Whilst it can handle extended 10A draw, technically, that requires everything to be in good order and the socket not to be worn out, dirty or just plain poor quality.
You could consider installing a 16A commando socket and buying a portable evse with a commando plug but that itself is quite fraught with potential issues and probably a fair amount of the cost towards doing it properly.

You could consider installing the appropriate cable yourself. There’s probably a route that lets you keep it out of view but it will take more effort so most installers don’t want to do that.

 

[Hitstirrer]

I'd like to be able to charge the car at home from a 3-pin plug in my garage. Is this a bad idea?

Yes, it's a bad idea.

But what is the size of the supply cable to the garage? And how does it get from the house to the garage? That supply may already be large enough to allow a 16 amp wallbox to be fitted. You may have to lose the 13 amp sockets and lights though as the wallbox has to be on its own dedicated fuse. In any case, the garage cable might have been fitted from the house through a duct and it may be possible to use that duct to pull a larger cable through so that a full-fat wall box can be fitted. Also, where in the house is the domestic CU situated? It may be possible to use a spare trip in there to get to the garage easier. There may also be a route through the house that would be more aesthetically pleasing than a cable clipped around the front wall. Many options. And all preferable to using a granny charger permanently.

 

[Stinsy]

+1 for 16A charging point.

Just do the job properly.

I own a few rental properties, it is very common to find kitchen sockets damaged from being used regularly to power kettles, toasters and other high-power devices. A granny cable draws the same power but not for just 2-mins like a kettle. Hour-after-hour.

 

[flemming]

Thanks everyone for their input! I think getting a proper charger installed is the way to go - and have the cable put under ground in front of the house.

The installer who came from Octopus did look at our supply in the garage and said the black cable wasn't thick enough to install the charger there (I presume the thickness is a good gauge of the ampage? I have no idea what I'm talking about of course!!! LOL)

I'll try and find a more accommodating installer and enquire about a better / more aesthetically pleasing route for the cable to the box 👍

 

[flemming]

Hi, are you able to reduce the charge current down from 10A to 6A or 8A?

This sounds interesting! I don't mind if it charges slower, but how might I go about reducing the charge current?

 

[Aragorn]

If the garage already has a supply, and running a new one is going to be disruptive, then the first job is to figure out the capacity of that existing supply.

Call a local spark out and get him to check out what is currently feeding the garage, cable size/type, protective devices etc. Or look yourself if your that way inclined. You can always post some images up here etc.

From there, you can figure out what capacity the cable has, and how much current you can draw. I would imagine even the most basic garage supply should be able to handle a 16A charger, and many of the common units can be adjusted down from the normal 32A.

A typical basic garage supply done in 2.5mm SWA for instance can potentially supply in excess of 30A depending on various factors. Likely plenty of scope to install a 20A charger and have some left over for the lights and sockets. Even if they've really skimped and done 1.5mm SWA, its probably still able to carry 20A+

Many of the big chargepoint installers dont seem that flexible or willing to think outside the box. They have a standard blueprint they want to apply to every job.

 

[Aragorn]

The installer who came from Octopus did look at our supply in the garage and said the black cable wasn't thick enough to install the charger there (I presume the thickness is a good gauge of the ampage? I have no idea what I'm talking about of course!!! LOL)

I note this. regarding my post above, take a close look at the cable jacket, usually the size is printed on it. See if you can find it. Is there some sort of distribution board in the garage already?

 

[Stinsy]

Thanks everyone for their input! I think getting a proper charger installed is the way to go - and have the cable put under ground in front of the house.

The installer who came from Octopus did look at our supply in the garage and said the black cable wasn't thick enough to install the charger there (I presume the thickness is a good gauge of the ampage? I have no idea what I'm talking about of course!!! LOL)

I'll try and find a more accommodating installer and enquire about a better / more aesthetically pleasing route for the cable to the box 👍

Obviously fitting a new cable and 32A charging point is the best solution. If you chose to go down this route then burying the cable yourself or hiring a groundworker to do it, is a good idea because electricians don’t like getting dirty and invoice accordingly.

However you shouldn’t be put off installing a charging point on the existing garage supply. I’m assuming the garage is wired in 2.5mm² SWA and is on a 20A in your house CU and the garage CU has a 16A for sockets and a 6A for lights. In this case a Zappi (or similar) charging point set to 16A with a CT limiting the total garage load to 20A would be a perfectly acceptable solution. The critical bit is that if you use a lawnmower (or other high power device) on the garage sockets while the car is charging, the Zappi (or similar) will slow down the car charging rate accordingly.

The only downside is that 16A is fast enough for most people but not all. You’ll add 150ish miles of range overnight, if you regularly do more than 150 miles a day it could be a problem.

 

[flemming]

OK, thanks for the recent comments! I've taken a couple of photos of the wiring in the garage. There's nothing printed on the black cable so I put a ruler behind it, it's about 14mm.

I can ask a local electrician for further assistance but I really like the idea of a 16A charger connected to the garage! I only do a couple of hundred miles a week so a full charge once a week is plenty!

 

[Aleras]

It looks like the garage has a 40 amp supply which can support a 32amp charger. The cable to the garage must be 3x 6mm at least What are the two 16amp circuits serving sockets and lighting? What do you use the sockets in the garage for ? If you have LED lighting and dont use sockets concurrently you should be able to run a 32amp charger off that supply.

 

[Stinsy]

It looks like the garage has a 40 amp supply which can support a 32amp charger. The cable to the garage must be 3x 6mm at least What are the two 16amp circuits serving sockets and lighting? What do you use the sockets in the garage for ? If you have LED lighting and dont use sockets concurrently you should be able to run a 32amp charger off that supply.

You can’t assume the garage has a 40A supply just because a 40A RCD is fitted!

 

[Stinsy]

OK, thanks for the recent comments! I've taken a couple of photos of the wiring in the garage. There's nothing printed on the black cable so I put a ruler behind it, it's about 14mm.

I can ask a local electrician for further assistance but I really like the idea of a 16A charger connected to the garage! I only do a couple of hundred miles a week so a full charge once a week is plenty! View attachment 174200 View attachment 174201 View attachment 174202

The overall diameter of 3-core 2.5mm² SWA is 14.1mm so that is probably what you’ve got.

If I were you I’d fit a new garage CU withe 3x circuits for neatness, but you can fit an additional one with just the charging point if you like. So long as your electrician is experienced fitting current-limiting charging points there should be no problem.

 

[flemming]

Is it easy for an electrician to test the supply coming into the garage?

 

[Stinsy]

Is it easy for an electrician to test the supply coming into the garage?

Yep. An ordinary electrician will have no problem doing a visual inspection of the cable that is accessible and testing IR, R1+R2, R1+Rn, etc.. If you get an “installer” from a big company they might have a company rule saying they can’t use pre-existing cables because they don’t trust their installers not to hang a 32A charging point off a length of lighting cable your grandad installed 40 years ago…

 

[JohnCollinson]

View attachment 174136

Granny chargers are not meant to be used as a long term charging solution used regularly for hours at a time. You are right at limits of a three pin plug. Anything suboptimal this is what can happen.

There are numerous examples of fires started using these things. Get a proper charger Installed trunk the cable mask it etc. I have mine clipped to brick work around front of house although mainly obscured with landscaping. It is what it is.

It will cost a fortune charging on public chargers and very inconvenient. You need a proper home charger correctly installed with appropriate TOU tariff.

They are not intended to be used as a long term charging solution.

Going back 12 ish years when I took delivery of my first Leaf (2010) they got you to sign a waiver that made it clear that should you choose to use the granny charger and your house burnt down, that was on you! You effectively were agreeing to install a proper EVSE.

 

[Aleras]

You can’t assume the garage has a 40A supply just because a 40A RCD is fitted!

Well that would not be a good install to fit a 40amp fuse to a cable thst cant support it. I guess the fuse could have been changed by someone though / non electrician. Obviously need to confirm the cable size prior.