No Power to the Sockets But the Lights Still Work? Here Is Why

It is an odd feeling. The lights come on as normal, the house looks completely fine, and then nothing you plug in works. The kettle is dead, the telly is off, and the fridge has quietly stopped without telling anybody.

The good news is that the split itself is a clue, and it usually points somewhere quite specific.

Why are the sockets and the lights on different circuits?

Because they are wired that way on purpose. Sockets and lighting are run as separate circuits from the board, each with its own protective device. It means a fault on one does not take the other with it, which is exactly why you are standing in a well lit kitchen with a dead kettle rather than in the dark.

It also means the fault is contained. If every light in the house is working, whatever has gone wrong is on the socket side, and you can ignore most of the installation straight away.

What should you check first?

Go to the board and actually look at it properly, rather than glancing at it.

• Is one of the smaller switches, the MCBs, sitting down while the rest are up? That is your circuit.
• Is the wider RCD down? If so it has detected a leak to earth rather than an overload.
• Is everything apparently up, but the sockets still dead? A tripped device is not always obvious. Some sit almost level. Push each one firmly off and back on.

Worth knowing before you go looking: your main fuse and the meter belong to ESB Networks and are sealed. They are not part of your installation and must never be interfered with. Everything from your board inwards is yours.

Why would only some sockets be dead?

This is where it gets useful. If a few sockets work and a few do not, the circuit is partly alive, and that points hard at a single bad connection rather than a tripped device.

Sockets on a circuit are connected in a chain. If a connection fails at one socket, the sockets after it lose supply while the ones before it carry on. Find the boundary between working and dead and you have usually found the room, sometimes the actual socket.

The usual culprits are a terminal screw that was never fully tightened and has worked loose over years of heating and cooling, a cable pushed too hard into a shallow back box when somebody changed a socket front, or heat damage where a high current appliance has been run through a socket with a loose terminal. That last one is worth taking seriously. A loose terminal generates heat at the joint, and heat in a back box behind a wall is how an electrical fault turns into something worse.

If a socket front is discoloured, warm, or smells faintly of hot plastic, stop using it, switch that circuit off and get it looked at. That is not a wait and see situation. It is also exactly the kind of thing worth sorting when replacing a socket or switch.

Could it be something you plugged in?

Very often, yes, and it is the cheapest possibility to rule out.

Unplug absolutely everything on the dead circuit. Not most things, everything, including the phone chargers behind furniture and whatever is in the shed. Then reset the device at the board. If it holds, plug things back one at a time and wait a moment between each. The item that brings it down again is the fault, and you have found it without anybody attending.

Kettles, toasters, washing machines and anything with a heating element are the common offenders, along with older extension leads. Garden and outdoor equipment is another, and if the trip lines up with wet weather the fault may not be an appliance at all.

When does it stop being a do it yourself job?

When the circuit will not hold with nothing plugged into it. At that point the fault is in the fixed wiring, and finding it means testing rather than guessing. An insulation resistance test across a dead circuit tells you whether the cable itself has failed and roughly where, which no amount of switching things on and off will.

The same applies if the RCD will not reset at all, if the board is warm, if there is any smell of burning, or if the board is an older one with rewireable fuses rather than modern protective devices. That is the point to stop and get somebody out to do proper fault finding on it.

Common questions

Why did my fridge freezer stay off after the power came back?

Some appliances do not restart on their own after a supply interruption, and some have an internal delay of several minutes to protect the compressor. Check the appliance's own switch and give it ten minutes before assuming the circuit is still dead.

Is it safe to use the sockets that still work?

If the fault is clearly one dead section and nothing is warm, discoloured or smelling, the live sockets are generally fine to use in the short term. If anything is warm or discoloured, or the protective device keeps operating, switch the circuit off and leave it off.

Could a light switch fault kill my sockets?

Not normally, because they are separate circuits. The exception is where the two share an RCD, in which case a leak to earth on the lighting side can trip the RCD and take the sockets down with it. In that case you would usually notice the lights going as well.

How long should it take to find this kind of fault?

A tripped device with an obvious appliance behind it is minutes. A loose connection somewhere in a chain of sockets means working along the circuit and can take a good bit longer, particularly in an older house where the run is not obvious. Knowing which sockets work and which do not before anybody arrives genuinely shortens it.

Before you ring anybody

Write down which sockets are dead and which are fine, whether any device at the board has gone, and whether anything was plugged in or switched on just before it happened. Those three answers turn a search into a check, and they cost nothing.