RCD protection explained
Missing RCD protection is one of the most common reasons a home fails its EICR. Here is what an RCD does and why it matters.
What an RCD does
A residual current device constantly compares the current going out on the line conductor with the current returning on the neutral. If the difference reaches 30 milliamps, which suggests current leaking to earth, possibly through a person, it disconnects the supply in a fraction of a second.
Where it is required
- Socket outlets rated up to 32 A
- Cables concealed in walls at a depth of less than 50 mm without other protection
- Circuits in bathrooms and shower rooms
- Lighting circuits in homes, under the current regulations
Why it is coded C2
Without an RCD, a fault on an appliance used outdoors or a nail through a hidden cable could cause a fatal shock. Inspectors usually code missing RCD protection for socket circuits as C2, potentially dangerous.
How it is fixed
Either by fitting RCBOs (combined RCD and circuit breaker) to affected circuits, or by replacing an old fuse box with a modern consumer unit. See consumer unit replacement cost.
Questions
How do I test my RCD?
Why does my RCD keep tripping?
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