Fault-finding 🇬🇧 UK
Why does my RCD keep tripping for no reason?
Here are the usual causes, most likely first, and how an electrician would track it down.
Likely causes
- One faulty appliance with earth leakage
- Too many circuits/appliances on one RCD (combined leakage)
- Moisture in an outdoor socket or light
- Borrowed neutral between circuits
- Faulty RCD
How you'd find it
- Unplug everything and reset; plug back in one at a time
- Isolate, then IR test each circuit (≥ 1 MΩ at 500 V)
- N–E test per circuit; RCD tester for trip time and current
Usual fix
Repair/replace the faulty appliance or wiring; separate borrowed neutrals; spread circuits over more RCDs/RCBOs.
⚠️ Safety: Stop and safely isolate before touching anything. If you're not qualified, leave it to a registered, competent electrician.
Regulation: BS 7671 411.3.3; testing 643.3 / Table 64.
Study aid in plain English, not the text of the standard. Always check the current BS 7671 and your local rules. Electrical work must be done by a licensed or registered electrician.
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