Power went off? How to reset a tripped RCD (FI-Schalter, GFCI) and find what tripped it

An RCD cuts the power within milliseconds when it detects current leaking away, for example through a faulty appliance or a person. That is why it trips (ADAC). If it's dark, use your phone's torch (and if it won't come on, see iPhone flashlight not working).

Same switch, three names

Step 1: find the switch that's off

Open the fuse box. The RCD is usually wider than the other switches and has a test button. If its lever is down, it has tripped (RBH). Look closely: ADAC says some switches stop half-way when they trip and look as if they are on from a distance.

Step 2: unplug everything on that circuit

Pull the plugs out. Switching off at the socket isn't enough, because the RCD can still detect a faulty appliance (RBH). Switch a cooker or electric shower off at its own isolator switch. Don't forget rarely used things like a freezer in the cellar, or extension leads and power strips (ADAC).

Step 3: push the lever fully down

If the lever is stuck half-way, push it all the way down first (RBH, ADAC).

Step 4: push it back up

Push it firmly up. If it stays on, an appliance was the cause (ADAC). If it snaps straight back down with everything unplugged, go to "If this doesn't work" below.

Step 5: plug things back in one at a time

Wait a few seconds after each one. When the RCD trips again, you've found the faulty appliance (ADAC). Leave it unplugged, reset the RCD, and don't use that appliance again until it's repaired or replaced (RBH, ADAC).

In the US: reset a GFCI outlet

Leviton says to look first: replace the outlet straight away if it is discoloured, warm or holds plugs loosely, and check what was plugged in for frayed cords. Think about what you were using when it tripped and unplug that device, as it may be faulty. Then press RESET. If it keeps tripping, or there is no obvious cause, Leviton says to contact an electrician.

If this doesn't work

• It trips again with everything unplugged: ADAC says the fault is then often in something wired in, like the oven, the heating or outside lights, or in the wiring itself. Call an electrician.
• Find the faulty circuit: RBH's method is to switch all the circuit breakers off, switch the RCD on, then turn the breakers on one at a time. Leave off the one that trips it, switch the rest back on, and call an electrician.
• Water near electrics, a burning smell or scorch marks: switch that circuit off at its breaker and call an electrician (RBH, Electrical Safety First).
• The power is off but every switch is up: check whether the neighbours or street lights are out too. In older buildings, there may also be main fuses before your flat's box, for example in the cellar or hallway (ADAC).
• Don't force it: holding the lever up won't work, because the switch is built to trip again while a fault exists (ADAC). Never bypass it.