Do EV chargers need surge protection? EV chargers along with other new electrical circuits require surge protection to comply with the technical aspects of the 18th Edition Amendment 2 of the Wiring Regulations. However, while the new regulations emphasise the importance of surge protection, they give homeowner’s the choice to opt out of an SPD during their EV charger installation. Note that EV chargers do not have a built-in SPD – the SPD is an external device installed by your electrician, usually at the consumer unit. Surge protection exists to protect your EV charger in case of ‘transient overvoltage’, sometimes known as a power surge or overload.
Your electrician will determine the correct SPD for your EV charger installation based on the location of the charger in respect to the consumer unit.
The installation of the SPD is part of a standard EV charger installation, so most quoted EV charger installation costs factor it in. However, as an optional extra, an SPD will set you back around £150.
EV chargers and surge protection
All new EV charger installations require surge protection with a Surge Protection Device (SPD). Existing EV chargers installations do not require retroactive upgrades but any changes to the circuit do bring the latest regulations into force – making an SPD necessary for the work to comply with regs. SPDs are usually installed within the consumer unit alongside a backup short-circuit protection device like an MCB.
Opting out of surge protection
New regulations highlight the value of equipping electric vehicle chargers with surge protection devices (SPDs) to safeguard against power surges. However, homeowners ultimately retain the choice of whether to include an SPD or not.
The regulations enable homeowners to opt out of adding surge protection if they judge the risk tolerable or have other reasons for declining. This flexibility allows each homeowner to weigh the risks and benefits and decide what works best based on their priorities and personal preference regarding SPDs for their EV charger installation.
Opting out of surge protection might affect your EV charger warranty although most manufacturers aren’t bothered about it. We recommend following your electrician’s advice following a survey of your home.
What do the regulations say?
The latest UK electrical safety standards in BS 7671:2018 mandate surge protection for all structures unless a documented risk assessment determines it is unnecessary. SPDs shield against transient overvoltages that could:
- Cause fatal injury or property damage.
- Disrupt vital public services or treasured historical sites.
- Interrupt business/industrial activities.
- Impact many co-located people.
The 18th Edition Changes don’t force retroactive upgrades, but modifying an existing circuit does require bringing just that portion up to current standards. Doing so without adding coordinated whole-house protection somewhat limits benefits.
According to the latest amendment of the British Standard BS 7671:2018+A2:2022, which covers the requirements for electrical installations, surge protection is mandatory for certain cases where the consequences of overvoltage could be severe, such as:
- Resulting in serious injury to, or loss of, human life.
- Resulting in failure of a safety service, such as fire alarms, emergency lighting, or medical equipment.
- Resulting in significant financial loss or data loss, such as in businesses, data centres, or public services.
For all other cases, SPDs are recommended to protect against transient overvoltages, unless the installation owner declines such protection and wishes to accept the risk of damage to both wiring and equipment as being tolerable. This is the ‘opt out’.
What are power surges?
Power surges are short spikes in voltage on the electrical system caused by lightning strikes, power grid equipment switching on or off, and other events. The extra jolt of electricity can fry electronics connected to your home’s wiring.
Why your EV charger needs protection
EV home chargers rely on advanced circuitry to safely and efficiently charge your electric car’s battery. A power surge can overload and permanently damage those components.
Surge protectors prevent thousands of pounds in damage by blocking excess voltage before it reaches your EV supply equipment – think of it is a diversion. They quickly divert the spike to ground and clamp the voltage to a safe level.
SPDs are relatively inexpensive devices and don’t require any changes to your house wiring (on another note, EV charger installations never require house rewiring) – if you’ve been told you need this, get a separate opinion from a reputable electrician. The NICEIC database is a good place to find one.
Choosing the Right SPDs
Several types of SPDs exist:
- Type 1 – Protects full electrical service at main panel. Best for main electrical service entry points where lightning rods exist or overhead power lines feed the structure
- Type 2 – Protects individual branch circuits. Best at the main distribution panel if no lightning protection present; also at any subpanels over 10-15 meters from the main
- Type 3 – Point-of-use protection at outlet. Best at local outlets for sensitive equipment requiring ultra-low let through voltage.
Experts recommend layered protection using Type 1 and Type 2 devices. Type 1 SPDs at your home’s main service panel will filter larger surges coming in from the utility lines. Type 2 SPDs installed at the subpanel feeding the EV charger will screen smaller spikes on that circuit.
Combination Type 1+2 units are commonly installed inside load centres/breaker panels. Make sure to size your SPD appropriately for the electric car charger’s amperage rating. Type 3 plug-in surge protectors do not provide adequate protection on their own.
Proper installation by a qualified electrician is key to optimum performance. The SPD ground connection should use a dedicated conductor to established building/service ground. Shorter wire runs between the SPD and supply conductors provide better surge response.
Allow room for possible future electric loads by choosing SPDs with at least 20% extra capacity. Also consider a surge-protected power strip to safeguard any ancillary equipment plugged into the EVSE outlet.
Hopefully we’ve answered your questions about EV chargers and surge protection. Did you also know you need to notify the DNO about EV charger installation? The good news is your electrician will do this for you as part of the service.
