How to Troubleshoot an RCD Tripping

Overview

An RCD that keeps tripping can be a nuisance. This guide covers diagnosing and fixing the issue.

Step-by-Step Fix

1. First, ensure your hands are dry and you are standing on a dry surface before touching the consumer unit. Locate the RCD that is tripping and switch off all the individual Miniature Circuit Breakers (MCBs) connected to it, so they are in the 'off' position (usually down). This isolates all the circuits protected by that RCD, preparing for a systematic fault finding process.
2. Now, firmly push the RCD switch back into the 'on' position (usually up). The RCD should now remain latched on without immediately tripping, as all the circuits are currently disconnected. If the RCD trips immediately even with all MCBs off, it indicates a fault within the consumer unit itself or the RCD unit, and you should call a qualified electrician.
3. Starting from one end, systematically switch on each MCB one by one, giving a few seconds after each one before moving to the next. Carefully observe the RCD each time you switch an MCB on. Pause and check if the RCD trips as you activate a particular circuit.
4. If the RCD trips as soon as you switch on a specific MCB, this pinpoints the faulty circuit causing the issue. Make a note of which MCB caused the RCD to trip, as this identifies the problematic area you need to investigate further. Switch off that faulty MCB again, and then you can reset the RCD and switch on the remaining MCBs to restore power to other unaffected circuits.
5. With the faulty circuit identified, unplug all appliances from sockets on that circuit, including extension leads, chargers, and anything directly wired in (e.g., dishwashers, washing machines) if safely accessible. Once all appliances are disconnected, try switching the problematic MCB back on; if it holds, plug in each appliance one by one until the RCD trips again, identifying the faulty appliance.
6. If you've followed these steps and cannot pinpoint the fault, or if the RCD trips immediately even with all MCBs off, it's crucial to call a qualified electrician. Electrical faults can be dangerous, and a professional can safely diagnose and repair issues within your consumer unit or wiring that are not apparent to a DIYer.

Common Symptoms & Diagnostic Resolutions

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions