An RCD is one of the most important safety devices in your home, yet many older properties still don’t have one. Here’s what it does and why it matters.
What an RCD does
An RCD (Residual Current Device) constantly monitors the electricity flowing in and out of a circuit. If it detects even a tiny imbalance — for example, current leaking to earth through a person or a fault — it cuts the power in a fraction of a second. That speed is what prevents a fatal electric shock and reduces fire risk.
RCD vs MCB vs RCBO
- MCB — protects the circuit from overload and short circuit (too much current).
- RCD — protects people from shock by detecting earth leakage.
- RCBO — combines both in one device, per circuit, so a fault on one circuit doesn’t knock out the rest of the house.
Do you need one?
Yes — current wiring regulations require RCD protection for most circuits, especially sockets, and for anything in bathrooms or outdoors. If your board has no RCD, it’s outdated and worth upgrading. It’s a common reason a board is flagged on an EICR.
How to check if you have one
Look at your consumer unit for a switch with a ‘T’ or ‘Test’ button. Pressing it should trip the power (then reset it). No test button usually means no RCD. We can upgrade your board — see consumer unit replacement.
Common questions
An RCD protects against electric shock (earth leakage); an MCB protects against overload. An RCBO combines both in one device per circuit, so one faulty circuit doesn’t take out the whole house. We fit RCBOs as standard where suitable.
Press the ‘Test’ (T) button on the RCD at your consumer unit — it should trip the power off immediately. Switch it back on afterwards. If it doesn’t trip, have it checked. Test roughly every three months.
Current wiring regulations require RCD protection for most circuits, and it’s essential for sockets, bathrooms and outdoor circuits. Older boards without RCDs are commonly flagged on an EICR as needing an upgrade.
No RCD protection?
Upgrade to a modern consumer unit with RCBO protection — get a fixed-price quote.
Call 020 7473 7807