Four rules cover almost everything.
1. RCD protection, always
Outdoors, on any mains machine. Either a protected circuit or a plug-in unit at the socket.
2. Extension leads, fully uncoiled
A coiled lead under load heats up. Uncoil the whole thing, use an outdoor-rated lead, and keep the connection off the ground and out of the water you are producing.
3. Isolate before you clean
Outdoor sockets, garden lighting, pond pumps, EV chargers, and anything in a garage that has flooded. Switch off first, clean second.
4. Never point a jet at electrics
Consumer units, junction boxes, outdoor sockets, car engine bays with exposed connectors, and the machine’s own plug. Water under pressure gets past seals that keep rain out — they were designed for rain, not for 140 bar.
Petrol, separately
Never run a petrol machine indoors, in a garage or in any enclosed space. The exhaust is carbon monoxide, it is odorless, and it accumulates.
The questions we hear
Do I need an RCD?
Yes, for any mains machine used outdoors. Many modern sockets are protected at the consumer unit, but a plug-in RCD costs very little and removes the doubt. If the machine is used away from the house, on an extension, it is essential rather than advisable.
Can I vacuum water near an appliance?
Only after isolating it. A wet and dry vacuum is designed to pick up standing water; it is not designed to make a flooded appliance safe. Switch off at the consumer unit, then clean.
Last reviewed 2026-08-15
