A ceiling starts dripping above a socket. A washing machine hose lets go behind a consumer unit in a hallway cupboard. A flat upstairs has a burst pipe and the water finds its way down through a light fitting. In every one of these, the first thing that happens is not a bang or a spark — it is the lights going out. The fuse board has tripped, and now you have two problems at once: water somewhere it shouldn't be, and no power in some or all of the flat.
This is one of the more common emergencies we see across Mayfair, Marylebone and Bayswater mansion blocks, and it sits awkwardly between two trades. Do you call an emergency plumber, an emergency electrician, or both? The honest answer is usually both, but the order and the first few minutes matter more than the phone call.
Why the board trips — and why that's a good thing
Modern consumer units are fitted with residual current devices (RCDs), which are designed to cut power the instant they detect current leaking somewhere it shouldn't — to earth, through damp plaster, a wet light fitting, or water sitting inside a socket. Under BS 7671, the UK wiring regulations, this is exactly what an RCD is supposed to do. A board that trips when water gets near the wiring is not malfunctioning; it is doing its job and very possibly preventing a shock or a fire. If your board is tripping repeatedly for no obvious reason, our guide to a tripping fuse board covers the non-water causes, and no power after the fuse box trips walks through what a total loss of power usually means.
The problem is that an RCD only protects the circuit it's wired to. It won't necessarily protect every socket in the flat, and in older mansion blocks with partially updated wiring, some circuits may have no RCD protection at all. That's why the response to water-and-electrics needs to be more deliberate than simply flicking the switch back on to see if it holds.
The first five minutes
- Don't touch anything wet. No switches, sockets, or appliances in standing water or visibly damp areas, even with the power already off at the board. Water can carry current for longer than people expect, and a "safe" isolated circuit can become live again if someone resets it without knowing why it tripped.
- Isolate the water first if you can do it safely. If the leak is from an internal pipe, tap, or appliance, turning off the stopcock (or the isolation valve under the specific fixture) stops the source feeding the problem. If the leak is coming from the flat above, you can't isolate at source — see our page on burst pipe emergency response for what to do while you wait for access to the flat upstairs.
- Leave the affected circuit off. If only part of the flat has lost power, resist the urge to flick the tripped switch back up repeatedly "to see." Each reset re-energises a circuit that may still have water sitting against live conductors.
- Don't run appliances to "dry things out." A hairdryer near a wet socket, or a heater pointed at a damp ceiling rose, is not a fix — it's a second hazard on top of the first.
Which trade to call, and in what order
In practice this is rarely a single-trade job, and treating it as one is how people end up with the electrics switched back on before the leak is actually stopped, or the leak mopped up while a live circuit is still sitting wet behind a light fitting.
Call a plumber first if the water is still running
An active leak that hasn't been isolated is the more urgent of the two problems, because every extra minute adds water to a space with electrics in it. An emergency plumber in Central London can isolate the source, and if it's a shared riser or a leak from a neighbouring flat, they can also advise what evidence to photograph for a freeholder or insurance claim.
Call an electrician once the source is stopped — or immediately if there's any doubt
Once the water is under control, the electrics need checking before anyone relies on that circuit again. This isn't a job for guesswork or a manual reset. An electrician can test the circuit, confirm whether the RCD tripped correctly or whether there's residual dampness still causing leakage, and safely restore power once it's genuinely dry and tested. If the fault is intermittent, unclear, or affecting more than one circuit, our page on electrical fault-finding explains how a proper diagnosis works rather than a trial-and-error reset.
If the leak has been running for any length of time — behind a consumer unit, into a light fitting, or across a floor with sockets at skirting level — treat it as an electrical inspection job even if the power seems to come back on fine. Water leaves conductive residue, and a circuit that tests as "fine" the day after a leak can develop a fault weeks later once corrosion sets in.
Landlords: what this means for compliance, not just repair
For a rented flat, a water-into-electrics incident is worth logging properly, not just fixing quietly. If the affected circuit or consumer unit shows signs of water damage, it may need remedial work recorded against your Electrical Installation Condition Report rather than left as an informal "it's working now." If the consumer unit itself is old, unlabelled, or lacks RCD protection on all circuits, this kind of incident is often the moment that surfaces it — our guide to consumer unit upgrade regulations explains when a board genuinely needs replacing rather than repairing around.
It's also worth noting in any correspondence with a managing agent or freeholder, particularly where the water originated from a shared riser, a flat above, or common parts — that record can matter later if there's a dispute over responsibility or an insurance claim.
The pattern that actually prevents this
Most water-into-electrics emergencies trace back to one of two things: a consumer unit or light fitting positioned somewhere it can catch a leak from above, or wiring that predates current RCD protection standards. Neither is something you fix in the moment — they're things a periodic electrical inspection is designed to catch before a leak turns it into an emergency call. If it's been a while since your electrics or your plumbing had a proper look, our emergency repairs across Central London team can also advise on the preventative side once the immediate problem is sorted.
If you're dealing with this right now — water somewhere near a socket, light fitting or consumer unit, and no power on part of the flat — get in touch for a fixed quote and we'll get the right trade moving first.