EICR Failures: The Most Common Causes

An EICR only fails on C1 (danger present) or C2 (potentially dangerous) findings — a report with only C3 recommendations still passes as Satisfactory. In practice, three issues account for the large majority of the "Unsatisfactory" reports we write across Poole, Bournemouth and Christchurch rental properties. None of them are exotic — they're just common, and worth knowing before you book an inspection.

Missing RCD protection Usually C2

An RCD (Residual Current Device) monitors the current flowing out through the live and back through neutral, and cuts the power in milliseconds if it detects a mismatch — the kind of mismatch that happens when current is leaking to earth through, say, a person. Since the 18th Edition of the wiring regulations, socket circuits generally need RCD protection (BS 7671 Regulation 411.3.3), along with circuits in bathrooms and outdoor supplies.

If a property's consumer unit predates this and was never upgraded, it's very likely missing this protection — and it's consistently the single most common reason an EICR comes back Unsatisfactory. The fix is usually a consumer unit upgrade to a modern board with RCBOs (one per circuit), rather than a piecemeal repair.

Missing or inadequate main earth bonding Usually C2

Main protective bonding connects the metal gas and water pipework entering your property to the electrical installation's main earthing terminal — normally with a green-and-yellow cable, usually a minimum of 10mm² copper, clamped near the meter or the pipe's point of entry. Its job is simple: if a fault ever makes those pipes live, the bonding gives the fault current a safe path away rather than leaving the pipework — and anything touching it — dangerously live.

It's a common finding for this bonding to be missing entirely, undersized, or disconnected (often after other work — a kitchen refit, a boiler swap — is done without it being reconnected properly). It's a straightforward fix, but not one to leave.

Overheating and DIY damage C1 or C2

Discolouration or scorch marks around a socket, switch, or inside a consumer unit are a clear sign of a loose connection or an overloaded circuit generating heat — and it's taken seriously precisely because it's a genuine fire risk, not just a cosmetic issue. We also regularly find damage traced back to non-professional work: sockets spurred off incorrectly, connections made without a proper enclosure, or exposed conductors inside a damaged accessory. Any of these can trigger an immediate C1 or C2, depending on how exposed the risk is.