ComGas installs home EV charge points across Farnham, Guildford and the surrounding area, starting with the supply capacity and earthing arrangement rather than treating the charger as a straightforward accessory. Load management and cable routing are planned around your property before installation begins.
An EV charger is a significant new load — it's assessed as one, not fitted like a socket.
A home EV charger can draw a substantial continuous current, often for hours at a time, which makes it a materially different addition to a property's electrics than a socket or a light fitting. Before specifying anything, we check the property's incoming supply and main fuse rating against existing demand, and establish the earthing arrangement the property has — because not every home's earthing is suitable for an EV charger without an additional measure.
Getting this assessment right at the outset is what determines whether a straightforward installation is possible, whether load management is needed to avoid overloading the supply, and how the charger is earthed. It's not a step we skip to get to fitting the unit faster.
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How we assess and install home EV charging
Supply, earthing, load management and routing — checked in that order.
Every EV charger installation starts with the property's supply and earthing arrangement, because those two factors decide what kind of installation is actually possible before the charger position or cable route is even discussed.
Supply Capacity & Main Fuse Assessment
The property's incoming supply and main fuse rating set a hard ceiling on how much load can be added, and an EV charger has to fit within it alongside everything else already running.
Main fuse rating checked against the existing property's demand and the charger's expected load
Most UK homes have a single-phase supply, which limits the maximum charging rate that can be safely and permanently drawn
Where headroom is tight, the charger's output is set or managed to stay within the supply's safe limits
The assessment is done before a charger is specified, not discovered once one is already fitted
Most UK homes are earthed via a PME (protective multiple earthing) supply, and that arrangement carries a specific, recognised risk for outdoor equipment like an EV charger that current regulations require to be addressed.
A PME supply relies on a combined neutral and earth conductor (PEN) back to the network; if that conductor breaks, exposed metalwork can become live
This 'open-PEN' fault risk is a recognised issue specifically for equipment installed outdoors, such as an EV charge point
Where PME earthing applies, the charger itself typically provides its own protection against this fault, or a separate earth electrode arrangement is installed
This isn't an optional extra — it's a safety requirement we assess and specify for on every installation, not something fitted only if asked for
An EV charger is wired back to the consumer unit as its own dedicated circuit, and where supply headroom is limited, a load management device keeps total demand within safe limits automatically.
The charger is installed on a dedicated circuit from the consumer unit, sized for its full load
Consumer unit spare capacity checked before installation, in the same way as any other new circuit
Load management devices reduce or pause charging automatically if the property's total demand approaches the supply limit, rather than requiring you to manage it manually
Particularly relevant on properties with other high-demand appliances, such as electric cooking or immersion heating
The route from the consumer unit to the charger position, and where the charger itself can practically be mounted, both depend on the property's layout and parking arrangement.
Cable routed from the consumer unit to the charger position, sized to avoid excessive voltage drop over the distance involved
Wall-mounted units fitted where a suitable wall is close to the parking space; post-mounted units used for driveways without one
Any cable run crossing a driveway or path is suitably protected, typically buried at an appropriate depth in ducting
Charging from a domestic supply routed across a public footway isn't something we can install safely or lawfully — off-street parking on your own property is required
The earthing question every EV charger installation has to answer
Not every home's earthing arrangement is straightforwardly suitable for an EV charger.
Most homes in the UK are earthed on a PME arrangement, where the network combines the neutral and earth conductor into a single PEN conductor for most of its run, splitting them again close to the property. It works reliably, but it carries a specific, recognised failure mode: if that combined conductor breaks somewhere upstream — an 'open-PEN' fault — exposed metal connected to the earth on that supply can become live relative to true earth. For equipment fixed indoors, this risk is managed within the wider installation. For equipment installed outdoors, standing on real ground, potentially being touched while a vehicle is also in contact with the ground, the regulations require it to be addressed specifically.
In practice, this means every PME property having a charger fitted needs either a charger with its own built-in protection against this fault, or a separate earthing arrangement using a dedicated earth electrode, so the charge point isn't relying on the PME earth at all. Which option applies is a decision, not a formality — it depends on the specific installation and the charger being used — and it's assessed on every job rather than left to the charger's default settings.
Most UK homes are earthed via a PME supply with a combined neutral/earth conductor
An 'open-PEN' fault is a recognised risk specifically for outdoor equipment on a PME supply
The charger's own protection, or a separate earth electrode, addresses this risk
This is assessed and specified on every installation, not left as a default setting
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15 May 2025
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Excellent service, highly recommend
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Incredible service — problems fixed perfectly once again.
Lee, Paul and the team at COMGAS are fantastic. They arrived on time and got straight to work, quickly identifying the root cause of the plumbing and heating issues I was experiencing.
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ComGas replaced my boiler and water tank at short notice. So glad i used them. Thank you
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Lee came out to the school I work in to look at a problem with our heating, he diagnosed the issue and was able to fix it on the spot in a neat and tidy manor. Would highly recommend
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26 March 2025
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I recently used Comgas for a gas and heating service, and I couldn't be more impressed! From start to finish, their team was professional, friendly, and highly knowledgeable. They quickly identified the issue with my heating system and explained everything in detail, offering both short- and long-term solutions.
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Definitely recommend friendly reliable service
Scott was helpful and reassuring regarding our boiler answered our concerns and explained the problem and best course of action thank you for your advice
EV charger questions
Frequently asked questions.
If you're planning a home charge point, get in touch and we'll assess your supply and earthing arrangement before recommending an installation.
Most can, provided there's off-street parking on your own property. Charging across a public footway from a domestic supply isn't something that can be installed safely or lawfully.
What is PME and why does it matter for EV charging?
PME is the earthing arrangement most UK homes have, using a combined neutral and earth conductor from the network. It carries a specific, recognised fault risk for outdoor equipment, which is why every PME property needs either a charger with built-in protection or a separate earth electrode for the charge point.
Do I need a dedicated circuit for an EV charger?
Yes. An EV charger is installed on its own dedicated circuit from the consumer unit, sized for its full load, rather than sharing a circuit with anything else.
Will an EV charger overload my electricity supply?
It can, alongside other high-demand appliances, if the total load isn't managed. We check the main fuse rating and existing demand first, and specify load management where the supply's headroom is limited.
Can I install an EV charger without off-street parking?
No — a charger needs to be installed on your own property with the vehicle parked off the public highway. Running a cable across a footway isn't a safe or lawful option.
Does installing an EV charger affect my consumer unit?
It usually adds a new dedicated circuit, so we check the board has a spare way and enough overall capacity before installation, in the same way as any other significant addition.
How is the charge point earthed if my supply is PME?
Either the charger provides its own built-in protection against the specific fault risk PME carries for outdoor equipment, or a separate earth electrode is installed so the charger isn't relying on the PME earth at all. Which applies depends on the specific installation.
Can the charger be positioned away from the consumer unit?
Yes, within reason — the cable route and its length affect voltage drop and cost, and any run crossing a driveway or path needs suitable protection, so we assess the route before confirming a position.
