Who should I contact to install an additional consumer unit for an Electric Vehicle (EV) charger?

  • 18 April 2018
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Had an EV installer around today. Took a look around and decided it was too difficult to wire back to the existing consumer unit and the easiest option was to fit an additional CU in the meter box (the charger unit will be adjacent to it). He suggested that my supplier might be able to arrange it as the job would entail isolating the meter while the work was done.

Is this something Ovo do or could arrange and if so how do I go about it?


Best answer by Transparent 19 April 2018, 10:21

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Updated on 24/05/22 by Jess_OVO


Great to hear you’re looking to install an Electric vehicle (EV) charger! Sounds like your installation may need to involve several parties, as it involves installing a consumer unit and isolator switch. 


The installation and maintenance of your consumer unit (also know as your fuse board) should be carried out by an electrician, we can’t recommend anyone specifically but find a registered electrician here.


As your supplier the part of this installation that we can help with is the fitting of an isolator switch:


What's an isolation switch?

An isolation switch (also known as a 'double-pole isolator') is a piece of equipment which can be installed on a metering supply that will allow the supply to be de-energised post-meter. The isolation switch should be fitted after the meter but before the consumer unit.


What's the purpose of an isolation switch?

An isolation switch is designed to act as a circuit breaker on the mains electrical supply, so that any electrical work that needs to take place within a property can be completed safely by a private electrician. It also negates the need for a supplier to send an engineer to the property to de-energise the cut out (and re-energise afterwards) so that any internal electrical work can take place.


What does an isolation switch look like?



The isolation switch is located on the right of this photo. When the switch is turned off,  there would be no power after the isolation switch, which in turn would allow a private electrician to complete any maintenance work or repairs on the member's internal electrical set up.

Who's responsible for installing an isolation switch?

An isolation switch needs to be installed by your supplier. This is because the supply would need to be de-energised via the cut out and private electricians are not permitted to work on the cut out. Therefore, the supplier would need to arrange for an engineer to go to the property to install one.


How can I arrange an isolation switch install?


Reach out to our Support Team in order to schedule in an engineer visit. As a non-essential maintenance job there is a charge for this, check this guide to see the current cost.


Once you’ve got the EV charger installed, we’d love to hear more about your EV wheels:red_car:


EV owner? Check out our exclusive EV plan - OVO Drive + Anytime!


Userlevel 2
Sorry for the delay in getting back on this and thanks for the reply. Been up to other things and still no charger installed yet!

So I read the linked thread and fully understand why the isolator switch works. May be being thick here though but if an isolator switch is inserted in the meter box between the meter and my existing CU, how would a second CU be connected into the supply? It can’t come from the existing CU as that entails all the same access problems I have getting the supply to the charger location in the first place.

Effectively, the new CU needs to tap into the supply before the existing CU. Can more than one CU be fed from the isolator switch or would it mean tapping into the existing cables somehow?
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Hi @Gif,

Yes, you can have two Consumer Units fed from the same separate isolator switch. That's the way I'd do it.

It's obviously slightly cheaper to omit the isolator switch altogether. The electrician would simply connect both CU's back to your meter. But every time an electrician needs to work on one of the CU's in future, he'd still need to snip the seal on the Master Fuse (100A) and call out an engineer from your DNO to check the installation and re-seal it.

Please ask for further clarification if you need it.
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Thanks for that and understood. You wouldn't believe how hard it is to get someone to install a charge point for you if it's anything other than a quick simple job. I'm beginning to have an inkling that there may be an incentive with the government grant to only take on the simple ones to maximise profit and the others can go whistle!

Looking for a few more local people now who are on the list and may be slightly more customer focussed shall we say!

That said, before that I have Chargemaster coming on Tuesday next week so we'll have a laugh at what they say. I've told them until I am blue in the face that it might need some innovative thinking but I'm not confident they have been listening at all.

Who knows, they may surprise me and actually do something radical like help me.
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Your comment raises a wider point of concern, @Gif.

There are several other Topics on this Forum where consumers have been complaining about the length of time they have had to wait for Smart Meters to be installed. There is a shortage of trained installers, with some geographical areas faring worse than others.

But the Smart Meters themselves are the forerunners of any number of smart devices which require installation by properly qualified engineers whose skill-set must be more extensive than that of an ordinary electrician or gas-fitter.

You've highlighted difficulties in getting a domestic EV Charging Point installed.

Next it will be Home Storage Batteries.

Then we'll need solar-panels rewired to directly feed those Storage Batteries instead of using their own inverters for Grid-connection...

... followed by Smart Washing Machines and Smart Freezers, using electricity only when it's below a defined cost-per-unit.

This new technology all requires installers who are trained in gas, mains electrics, wireless communications, software configuration and basic electronics diagnostics. That's quite a list, even though the depth of knowledge in each field may not be great.

I note that OVO are committed to having their own team of Meter Installers... which is wonderful.

But the need won't stop once we all have those Smart Meters.

It would be wonderful if we could just email OVO and get a site visit from a single engineer who can install "all things smart".

How much easier that would be than the problem you currently face, having to get three firms to coordinate their actions:
  • local electrician
  • Western Power (your DNO)
  • EV Charger-point installer

Let us know how your EV Charger installation goes. We may all have lessons to learn.
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Well, I have to say that the guy chargemaster sent was a breath of fresh air. He couldn’t have been more helpful and the job is now sorted. Brand new 32amp lockable charge point installed and working. Full marks to them and if anyone is thinking of using them, I would highly recommend it.:D
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That's good to hear, @Gif. Full marks to Chargemaster :)

Did you actually have a new/second Consumer Unit installed?

Or did Chargemaster find a way to connect the 32A feed via your existing consumer unit (or even directly off your Meter)?

Good comment about the charge-point itself being lockable. I had previously imagined it being necessary to have an isolator switch inside the house to prevent someone else "stealing" your electricity.
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They managed to use the existing CU after a bit of trial and error regarding access but the critical thing was, they came ready to install a new CU and to pull the main fuse and split the meter tails all on the day if plan A hadn't been possible.

The lockable units are not rocket science as it's only a simple turn key solution and not high security, more just a deterrent. You could of course use the CB in the CU to turn it off but CBs are not designed to be switches and would quickly become damaged.

That all said, on the front of the house, I cannot imagine anyone trying to freeload the charger anyway, it would be too obvious and at 7kw, they would have to be there too long to get any value out of it and they would then risk being found out. On a typical tariff, you would have to have a typical EV on the driveway for about 4 hours to fill it and even then you'd only steal about £4. Is it worth getting a criminal record for theft for that? Or even worse, the word "Freeloader!" emblazoned on the bonnet of your car in paint stripper?

The greater concern with these things in my opinion is vandalism or theft. I can see someone thinking that a charge point might be a useful thing to nick or even worse when they become commonplace, some idiot going down the street cutting all the tethered cables off to try to make £5 at the local scrappy. :@

I already have a charger installed in a garage which is good as the unit itself is out of harm's way and it is surprising how easy it is to disguise the tethered cable even when it is permanently mounted on an outside wall.

This latest charger is more of a challenge being mounted on the front of the house. I am however working on how to disguise it sufficiently such that some oik won't see it when driving past. The one thing I don't like is the fact that the manufacturers use LEDs (which can't be turned off) to signal functions to the user. This makes them very visible at night. 😞
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Those LEDs sound like a welcoming message for a would-be vandal @Gif.

What about covering them with a laminated sign:

WARNING - High Voltage:

Danger of death
Isolate at internal switch before disconnection


After I signed on to EV Everywhere, Charged EV gave me an appointment for installation about 5 weeks hence.  A engineer arrived on the appointed day, but said he had come just to do a survey. He hadn’t seen the information and photos I had sent ChargedEV.  After looking at my system he said a main isolation switch would have to be fitted before the charger could be installed.  On the phone, Ovo said this would cost me £158 and the earliest appointment they could offer was about 9 weeks away. 

    This is a gentle warning to others that the installation process may be neither fast or free.  A lot of time could have been saved if I had been asked, at the start, whether I had a main isolation switch.  ChargedEV are not great communicators.    

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I think we could do with a bit more clarification please @Robin Fox.

Do you mean that your existing Consumer Unit doesn’t have a 100A Switch Disconnector within it?

Or is it that OVO require you to have another one between the Smart Meter and the Consumer Unit?

I have both… which means the Consumer Unit can be isolated without having to pull the 100A Service Fuse (and get the Distribution Network Operator to reseal it). Here’s the separate box which just houses a disconnector:


If you don’t want to wait 9 weeks and pay £158 then you could surely just get a local electrician to install one similar to mine in the photo?

Although I bought a separate switch and enclosure, you can now get an all in one unit, designed for just such a scenario. Here’s one available from TLC-Direct at £13.45 +VAT.


Obviously you first need to confirm with OVO that such a unit would achieve what they’re after. Direct them to read this Forum post if it helps.

Many thanks for your help, Transparent.  My consumer unit does have a 100A switch disconnector, so its seems that the engineer was recommending an additional one such as you describe.   I love the idea of doing this for £20-odd, but the Ovo person told me installation had to be done by their man (or woman), and I I imagine that most of the £158 would be for labour .

Just to clarify, an electrician is NOT allowed to cut seals and pull the main fuse, you have to work under a mocopa, to be able to do that, its illegal even tho they do ! 

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Thanks @Bigstee, and for those readers seeking a translation….

MOCoPA = Meter Operation Code of Practice Agreement


I live a rural part of the Westcountry and have been party to telephone calls between local qualified electricians and our DNO (Western Power) over the years. It is usually the case that WPD are indeed present when it is necessary to pull the fuse. But I have witnessed occasions where the response is “We can’t get to you for another half-hour yet; pull the fuse and continue your work in the meantime.”

Perhaps I am biassed in that such conversations have only occurred where it is a reputable local electrician, well known to the area DNO Engineers.