Installing an EV charger does not require rewiring your house. The electrical work is usually confined to creating the new circuit between the consumer unit and charger. In some cases, a larger consumer unit is required if the old one doesn’t have space for a dedicated circuit, and if your house has a 30amp or 60amp fuse, it will need upgrading to an 80amp or 100amp use. But a full house rewire? That’s almost unheard of just for installing an EV charger.
Even the most old fashioned domestic electrical installations can support an EV charger. The simple fact is that you need a dedicated 32A cable running to your fuse box, and you need a fuse that supports the power requirements of your load demand. Most houses have a 30 or 60amp fuse – an 80 or 100amp fuse is required for an EV charger. The good news is your electricity network provider will upgrade your fuse to 80 or 100amp for free – you can apply with the National Grid but we recommend going through your DNO which you can find here. This is the most common upgrade necessary for an EV charger and rewiring isn’t remotely related to it.
Once you have that fuse upgrade, adding an isolation switch provides a safe way to install an EV charger without needing the power company to shut off electricity. The switch acts like a circuit breaker, letting a private electrician safely connect the charger’s wiring. This avoids fees and delays of scheduling utility visits just to deactivate and reactivate the main power during installation. With the flip of a switch, you isolate the electrical supply for safe, convenient EV charger set-up. Note that an isolation switch needs to be installed by your supplier.
House rewire for EV charger
Your house does not need rewiring for an EV charger. At worst, you might need a new fuse, CU feeds fed from the Henley blocks, MCBs, 32A cabling, and fresh wiring leading up to the fuse box. You might even need a new fuse box that complies with BS 7671:2018.
The incoming supply and tails should be good on houses with original electrical installations dating back into the 1970s or earlier. There should be no need to rewire a whole house because of an EV – unless there is something drastically wrong.
If you’ve been told your house needs rewiring for an EV charger, get a second opinion from a registered electrician – you can find one using this tool from Electrical Safety First or you can tap into the NICEIC database instead.
If you have an ancient meter, asking the DNO to upgrade the fuse and getting your supplier to install a new metre will modernise much of your installation. You can then get an electrician to upgrade the parts necessary for an EV charger.
Just keep in mind that you might not get 100amps out of your current installation if it’s extremely archaic – in which case, the DNO can uprate and modernise your supply.
Other electrical modernisations you might need
Your old electrical installation probably doesn’t need rewiring for an EV charger, but the IET Code of Practice for Electric Vehicle Charging Equipment Installation, 4th Edition aims to address safety issues that have emerged as EV adoption has grown.
Key areas include proper grounding and detection of wiring faults, which reduce risks from shock and electrocution. The regulations tackle problematic “TT islands” – separate grounding electrodes for EV equipment that can be unsafe. Burying electrodes risks striking buried pipes or cables. Also, inadequate separation from buried metal building systems connected to protective multiple earthing (PME) eliminates safety benefits.
Safety first when working with electrics
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To avoid TT islands, updated guidance recommends open PEN detection devices. These monitor voltage between the EV wiring’s protective ground and either a separate ground electrode or the building’s electrical system to verify proper isolation.
If faulty wiring is detected, the device disables the charger. Homeowners with TT islands may consider replacing their grounding approach with these devices.
Another safety risk is overloading shared neutral wires. The updated standard eases criteria for balancing EV loads across electrical phases to alleviate this, benefiting homes with 3-phase supplies. Owners planning additions like extra chargers should review guidance on judging whether loads are sufficiently balanced to avoid upgrades.
The new integration and smart grid capabilities also offer homeowners ways to leverage their EV batteries as on-site power storage. Guidance assists properly incorporating vehicle-to-grid and vehicle-to-home links into an overall local renewable energy and storage strategy.
In summary, homeowners with existing EV charging can reference updated electrical codes and guides to identify safety improvements for their supplies.
Prudent measures include re-evaluating earthing provisions and protection against phase overloads and faults. Thoughtful upgrades will serve reliability, safety and expanding capability needs as personal EV usage grows.
DNO? What’s one of those?
The DNO (District Network Operator) owns your main electrical fuse and the fuse holder (the cut out) – this is the fuse that only they can upgrade for you.
The DNO also operates the cables that bring electricity from the grid into your house, so most electrical upgrades for EV chargers – including 3-phase installations – start with the DNO.
Different regions have different DNOs – in London and the South East, it’s UK Power Networks, in Yorkshire it’s Northern Powergrid, etc. These are the chaps that own your fuse and any house rewiring or modifications will start with them.
Here are some insights into electricians and DNOs:
- DNOs own and control the electricity distribution network leading into homes and businesses. They are responsible for the main fuses and supply equipment.
- Electricians often face frustration and delays due to having to wait for the DNO to disconnect main fuses, which only they are legally allowed to do.
- If there’s no intact seal on the main fuse, the DNO should still be contacted. Electricians should never disconnect a main fuse themselves without DNO approval as it’s illegal.
- Response times from DNOs to dispatch technicians can vary greatly. Some are quick to help while others take much longer leading to delays. There’s no reliable way to speed this up, other than chasing up with them.
- If your house has an isolator switch on the supply, your electrician can bypass the main fuse for work. This avoids DNO delays, but comes at an extra upfront cost to the customer.
- Most electricians feel competent to safely disconnect main fuses when needed, but rules force them to wait for the DNO regardless.
- If the main fuse has to be pulled, electricians have no choice but to follow DNO procedures. Breaking rules risks serious penalties from regulators.
Upgrading your main fuse for an EV charger
Whether you need a new main fuse depends on the amperage of your existing fuse and what condition it’s in. Here’s everything you need to know:
- The main electrical fuse controls the amount of power flowing into a property. Older properties often have 30 or 60 amp fuses, which are now inadequate for EV chargers.
- Upgrading the main fuse is often needed to support modern high power devices like electric vehicle chargers. Common upgrades are to 80 amps or 100 amps.
- The fuse itself and cut-out box it sits in are owned by the Distribution Network Operator (DNO). Only they can change the fuse. The connecting cables can be the responsibility of others like electricians.
- Before a fuse upgrade, the electricity meter and connected cables must also meet certain ampacity requirements to handle the extra current safely. For an 80 amp fuse upgrade, cables must be at least 16 mm2 copper. For 100 amp upgrades, 25 mm2 copper cables are mandated.
- The consumer unit (fuse box) where power is distributed inside the property must match or exceed the upgraded main fuse capacity. So 80 amps main fuse needs an 80 amp or bigger consumer unit.
- Some homes have a dedicated isolation switch that allows an electrician to safely cut power to the property momentarily without needing the DNO’s involvement. This facilitates upgrades more quickly.
Can my electrical panel handle an EV charger?
Whether your electrical panel can support an EV charger depends on the amperage of your existing service, the number and types of electrical appliances you currently have, and the charging speed you need for your electric vehicle.
To determine if your panel can handle an EV charger, an electrician can perform a load calculation to measure the amps currently in use. This accounts for appliance wattage and square footage but assumes you don’t use everything at once.
If the panel can’t support an EV charger, you can either upgrade your fuse/service, which provides more capacity, or install an energy management system to shut off the EV charging if electrical load exceeds 70%.
Smart chargers like the Ohme ePod have dynamic load balancing built in to stop circuit overloads by setting a safe maximum amount of power. This works via a current sensor (CT) clamp to measure the electrical demand of the property, or sub-board.
Getting professional advice is recommended to ensure your panel or home wiring can safely handle EV charging. There’s a chance you’ll need a few upgrades, but a competent electrician will tell you what’s what.
Hopefully we’ve answered your questions about EV chargers and house rewires and given you enough insight to get cracking with it.