When you add a heavy load like an EV charger or heat pump, the installer must check whether your current supply can carry it. Many homes only need a smaller job, and some network operators will upgrade an older 30A or 60A fuse to 80A or 100A free of charge. A bigger upgrade such as moving from single to three phase is chargeable and can be expensive, so you should plan your supply before you book an installer slot.
Why the supply into your home matters
Every house has a main incoming electrical supply. This is where the heavy cable from the street meets the equipment inside your property. The main fuse sits right at the start of this setup to protect the incoming cable from drawing too much current.
Older homes were often built when people used far less electricity. A house might have been perfectly safe running a television, a fridge and a few lights on an older 30A or 60A main fuse. Today, our demand for electricity is much higher.
Adding a large, continuous load changes things. An electric car charger, a heat pump or an electric shower draws a significant amount of power for hours at a time. If charging would exceed the circuit breaker's rating or the service cable's capacity, you have to check with your network operator.
If the supply cannot handle the load, your energy network operator will need to upgrade your supply. Do not add heavy appliances until the installer has checked that the supply can carry them.
What the installer checks first
Before anyone fits a new charger, they have to make sure your home is ready. Installation contractors must examine the energy device and required connection to see what the property can handle. They assess your home's maximum load by looking at what you already own.
During the assessment, a good electrician will check several things:
- The rating of your current main fuse.
- Whether your consumer unit has spare ways for a new circuit.
- The condition of your earthing and bonding connections.
- The presence of RCD protection for the new equipment.
Your electrician will also check your earthing and bonding. This is the system of green and yellow wires that connects your pipework and electrical installation to the ground. Good earthing ensures that if a fault happens, the current flows safely away into the earth rather than giving you an electric shock.
Finally, they look at the main fuse itself. You must never touch the cut-out, remove covers or try to change a fuse yourself.
Why you cannot skip the load assessment
Every electrical installation is governed by the national wiring standard, BS 7671, often called the Wiring Regulations. The installer should check that the existing supply can handle the extra load before adding a new circuit. This is why a load assessment matters.
A good electrician will calculate the maximum demand of your property. They look at the fixed appliances like ovens, induction hobs and immersion heaters. Heavy loads such as an EV charger can draw a high current for hours at a time, often overnight. If your electrician skips the load assessment, they risk overloading the service cable.
If the assessment shows your supply is too small, you have to act. You may need the network operator to upgrade your supply. Ask your installer what options they recommend for your home.
Connect and notify or apply first
The rules for adding heavy equipment depend on the total load. Solar PV, heat pumps, EV charge points and battery storage all require notification of the local network operator. How and when you notify them depends on the size of the new demand.
If the load is small enough, the installer can use a process called connect and notify. For heat pumps where the maximum demand is 60A or less, installers may connect first and then notify within 28 days of the installation. If you only need to connect and notify, you install first then send the form.
Heavier loads trigger a different rule. For an EV charger, you must apply to connect before installing if any screening question is a yes. For heat pumps, where the maximum demand is 60A to 100A you must apply for a connection prior to installation.
The same applies if your single phase supply is rated between 60 and 100A and you now require more than 100A. In this case, you must send the form to the network operator. It is the energy device owner's responsibility to ensure that the network operator has received this notification.
Free fuse upgrades from the network operator
Many homes only need a smaller job than a full supply upgrade, such as a larger main fuse. The main fuse is owned and changed by the network operator, so do not touch it yourself.
At least one network operator states that for older 30A or 60A fuses, they can upgrade these to an 80A or 100A fuse free of charge. You must check with your own operator, as policies differ across the country.
This free service only covers the fuse itself. The network operator's engineers do not do any work on your side of the meter. Your electrician handles the internal work.
Your electrician should be on hand for any internal electrical works including connecting from your meter to your consumer unit. The two tradespeople often need to coordinate their visits so you are not left without power or a working consumer unit.
When a bigger upgrade is needed
Sometimes a 100A fuse is not enough to run a modern home. If you want a fast EV charger, a large heat pump, an induction hob and multiple electric showers, you may exceed what your existing supply can carry. In that case your installer or network operator may suggest a bigger upgrade, such as three phase.
A three phase supply brings three live wires into your home instead of one. This splits the load and gives you far more capacity. One network operator states that most homes and small businesses can upgrade from a single phase supply to a three phase supply, giving you up to 69kVA of power.
Changing the capacity of your supply is tightly controlled. Increasing your maximum import capacity, known as your MIC, could result in the need for reinforcement of the network. This means the work may be larger than a simple fuse change.
You have to plan these changes carefully. You can only change your MIC once within each 12-month period. If you later decide to reduce your capacity, there will be no charge associated with reducing your MIC.
What a three phase upgrade can cost
Moving to a three phase supply is a major undertaking. Unlike a simple fuse swap, upgrading to three phase is a chargeable service.
One network operator published the average cost of upgrading to three phase power, rated at 80A per phase, as £5,370.00. The page does not state when this figure was set, and your own quote may differ.
The table below shows the typical situations and outcomes for different supply needs.
|
Situation |
Typical outcome |
|---|---|
|
Older 30A or 60A fuse |
Upgrade to 80A or 100A free from at least one network operator |
|
Single phase 60A to 100A needing more than 100A |
Apply to the network operator first |
|
Single to three phase |
Chargeable, average £5,370.00 at one network operator |
These figures come from individual network operators, so check with yours.
Who does which part of the work
Understanding who owns what stops you paying the wrong person. The network operator is the company that runs the local cables, not the supplier you pay your electricity bill to. They own and change the main fuse.
If the main fuse needs upgrading, you have to contact the network operator.
Your electrician takes over from the meter onwards. They install the consumer unit, the new circuits, the surge protection device and the EV charger itself. A surge protection device stops sudden spikes in voltage from damaging sensitive electronics like your new car charger.
In England, any new circuit installation is classed as notifiable work under the Building Regulations. Approved Document P (2013 edition, for use in England) confirms that installing a new circuit and replacing a consumer unit are notifiable work. Registered electricians can self-certify this work and issue the correct electrical certificates.
How long it takes and how to plan
You must plan a supply upgrade well before your new car or heat pump arrives. Network operators can be busy, and applying for a connection takes time. If you need network reinforcement, expect it to take longer.
When you apply for a three phase upgrade, one network operator says its quotation is valid for 90 days. You have time to review the costs and decide if you want to go ahead, but you should not book your EV charger installer until you know the supply date.
Once you accept the quote, things move forward. One network operator states that your project manager contacts you within two working days of payment to plan the work. They will agree a date to dig any trenches and lay the new cables.
Ask whether the work will need your supply switched off, and for how long. Your own electrician will handle the internal work, including connecting from your meter to your consumer unit.
What an EV charger installation typically costs
The cost of upgrading your supply is entirely separate from the cost of the charger. The network operator charges for their cables, and your electrician charges for the device and the internal wiring. You need to budget for both if an upgrade is required.
Published prices for 2026 show it now typically costs between £500 and £1,200 to buy and install a home EV charger.
There are many different chargers on the market. For most homes a 7kW charger is a good choice and costs around £900 installed. Ask your installer to confirm that your supply can carry the load.
Your quote should include a fixed price for the charger and the standard fitting. Quotes may or may not include VAT, materials, certification and making good plaster and decoration, so always check the details. Any supply upgrade costs are extra.
You can read more about what affects an electric car charger installation at home to help you compare quotes.
What paperwork to expect after the installation
When the work is finished, you should receive several important documents. Good paperwork proves the job was done safely, meets the Wiring Regulations, and complies with the law. You should keep these documents safe for when you eventually sell the property.
You should expect to receive:
- An Electrical Installation Certificate for the new circuit.
- A Minor Works Certificate if they only carried out a small repair.
- A Building Regulations compliance certificate from the scheme operator.
- A copy of the notification form sent to the network operator.
Because an EV charger or heat pump requires a new circuit, your electrician will issue an Electrical Installation Certificate. This document lists the test results for the new wiring and confirms it is safe to use. If they only did a small repair along the way, they might issue a Minor Works Certificate instead.
You will also receive a Building Regulations compliance certificate. Electricians registered with a government-authorised competent person scheme, such as NICEIC or NAPIT, can self-certify their notifiable work. The scheme operator then informs your local building control department and posts the compliance certificate to you.
If you are unsure about the rules, read our guide on electrical certificates and part p for more detail.
Common questions
Can I check my own main fuse rating?
Leave this to your electrician or the network operator. You must never remove covers, open a consumer unit or touch the wiring or the main fuse to check it.
Do I need a new consumer unit for an EV charger?
Not always, but your electrician will check if your current board has spare ways and the right RCD protection. If your consumer unit is obsolete or damaged, your electrician will advise whether it needs replacing.
Who tells the network operator about my new charger?
Installation contractors classify the connection and submit the forms. However, the energy device owner is responsible for making sure the network operator has been told. You should ask your installer for a copy of the notification receipt.
What happens if my supply cannot handle the load?
If charging would exceed the circuit breaker's rating or the service cable's capacity, your energy network operator will need to upgrade your supply. Ask the installer to confirm in writing that the supply can carry the load before work starts.
Can I add a heat pump and an EV charger at the same time?
Possibly, but the combined load needs to be assessed first. Whether you can connect and notify or must apply first depends on the maximum demand, so tell your installer about both plans.
What to ask before you book
When you are ready to hire someone to fit your new charger, ask these questions to avoid delays and unexpected costs. A good electrician will be happy to walk you through the process and explain exactly what is included in their price.
- Has the maximum load of the property been assessed?
- Who notifies the network operator about the new device?
- Is a main fuse upgrade free with my specific network operator?
- Will the work need the electricity supply switched off, and for how long?
- Does the quote include all materials, VAT and certification?
- Who makes good any damage to plaster or decoration?
Finding a reliable tradesperson makes the process much smoother and ensures your new equipment is installed safely. When you are ready to get quotes, you can find an electrician near you to assess your supply and plan the installation.
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