What is a Surge Protection Device (SPD)?

A Surge Protection Device (SPD) helps protect your electrical equipment from sudden increases in voltage, known as power surges. These surges can be caused by events such as lightning strikes, faults on the electricity network, or large electrical appliances switching on and off.

What does an SPD protect?

An SPD is designed to protect sensitive electrical equipment connected to your system, including:

• Your Ohme charger
• Your electric vehicle
• Other electronics in your home

Without protection, power surges can damage internal components, reduce product lifespan, or in some cases cause complete failure.

Why are SPDs included in charger installations?

SPDs are commonly included as part of EV charger installations because:

• EV chargers are high-value electrical devices
• They are permanently connected to your home’s electrical system
• They may be exposed to outdoor conditions and grid fluctuations

In many cases, including an SPD aligns with current wiring regulations and best practice for protecting your equipment.

How do I know if I have an SPD?

An SPD is usually installed within your consumer unit (fuse box) or alongside your charger installation.
You can identify one by:

• A small module with a status indicator light or window
• Labels such as “SPD” or “Surge Protection Device”
• It may be installed by your installer as part of your charger setup

If you’re unsure, a qualified electrician can confirm whether one is installed.

How do I check if my SPD is working?

Shown in this reference image on the left side, most SPDs have a visual indicator (usually a small coloured window or light) to show their status:

Green – protection is active
Red or no light – the SPD may no longer be providing protection

We recommend checking this periodically, for example every few months or as part of general home checks.

Do SPDs need to be replaced?

Yes. SPDs gradually wear out as they absorb power surges. This happens over time and isn’t always visible unless you check the indicator.
If the indicator shows red or no light, the SPD should be replaced by a qualified electrician to ensure your equipment remains protected.