RCD tripping in rain traced and fixed, Hamidian, Rasht

The brief

A detached house whose RCD tripped in every rain, taking the whole building off. A previous electrician had suggested removing the RCD. The owner wanted the cause found, not the house’s protection taken away.

How it was done

1. 01 Function and trip-time test of the RCD itself to confirm it was healthy
2. 02 Insulation test of every circuit with a megger, dry and again after controlled wetting of the outside wall
3. 03 Junction box on the garden wall found with a cracked lid and water standing in it
4. 04 Garden lights replaced with properly rated fittings, cable entering from below
5. 05 Box replaced with a weatherproof enclosure and cable glands
6. 06 Outdoor circuit split onto its own RCD so any future fault does not black out the whole house

The outcome

The RCD stayed in place and the tripping did not return in later rain. Insulation results from before and after the repair were handed to the owner for comparison.