RCDs in domestic installations under the GREI

The main RCD: 300 mA at most

At least one RCD of 300 mA at most is placed at the origin of the installation. It also provides isolation.

In domestic installations, all RCDs are at least type A. The one at the origin of the installation has a rated current of at least 40 A (subsection 5.3.5.3).

Its input terminals are made inaccessible: the approved body seals them during the conformity inspection.

30 mA RCDs

Directly downstream of the main RCD, at least one high or very high sensitivity RCD, that is 30 mA at most, protects at least:

• socket outlets that do not supply a fixed appliance;
• lighting;
• bathrooms and shower rooms;
• the washing machine, tumble dryer and dishwasher.

Each of these RCDs protects 8 circuits at most.

Fixed appliances, such as the fridge, the cooker or electric heating, may be connected directly under the main RCD, or under another RCD placed at the origin of the installation.

Earth electrode above 30 ohms

If the earth electrode resistance exceeds 30 ohms, at least two 30 mA RCDs are needed, and each covers at most 16 single or multiple socket outlets.

Fixed appliances connected under the main RCD then also get an RCD of 100 mA at most, per circuit or per group of circuits.

Heating in floors or walls

Electric heating with resistance elements embedded in the building structure, supplied at more than 25 V AC, is protected separately by an RCD of 100 mA at most.

An old installation

When an old domestic installation is substantially modified or extended, the whole installation is protected by at least one main RCD of 300 mA at most.