An MCB protects against overload and short circuit. An RCD detects earth leakage but has no overcurrent protection. An RCBO combines both in one device and is the standard for individual circuits.

BS 7671 requires protection against transient overvoltages to be assessed on every installation. In practice a Type 2 SPD is specified as standard on new and replacement consumer units, and on circuits supplying EV chargers, solar inverters and heat pumps.

It depends on whether the charger has its own DC leakage detection. Chargers with it can normally use a Type A device upstream. Without it, a Type B device is needed. Always check the charger’s installation manual.

Amendment 2 of BS 7671 addresses AFDDs for higher-risk situations such as buildings with sleeping accommodation. Whether they are required or recommended depends on the building type and the current wording, so check the regulation in force and see our arc fault detection guide.

IP40 protects against solid objects over 1mm and gives no water protection, so it suits dry indoor locations. IP65 is dust-tight and protected against water jets, and is needed outdoors or where moisture may be present.