Install light timer switch

Hi @melzmark

The White (Neutral) wire in the switch must be the load wire.

This is not unusual as the light will already have a Neutral and Hot wire connected at the connection terminals in the light itself as part of house light power multiple, BUT only the White (Neutral) is connected to a light bulb terminal. The Black wire (hot wire) is not connected to the light but just to a spare terminal in the light fitting and from the light fitting a two wire cable (Black and White) is run down to the switch.

The Black wire connects to the other black wire on the spare terminal and the White wire is connected to the other lamp terminal.

Just connect the black wire to the Black wire in the timer and the White wire to the red wire in the timer.

Hi @melzmark

If you have connected the switch black wire to the timer black wire, the switch white wire to the timer red wire and the switch earth wire to the timer earth wire and it still doesn't work, chances are the earth wire is not connected at the other end of the switch cable. This is not unusual if the switch cover or mounting plate has a plastic body and is not a metal box.

There is a way to make the switch earth wire work as a Neutral wire to make it work, to save running in another cable from the light to the switch.

Remove the fuse box lights fuse (or trip the breaker) and then remove the lamp fitting that you want to control with the timer to expose the cabling connected to the lamp

Be safety aware and check that no lights work in the house before removing the lamp fitting

At the switch end connect the switch cable earth wire to the timer white wire.

Note: Wrap some electrician's tape around the earth wire and white wire to completely insulate the bare earth wire as once the following is done it will be "live" with power for the timer itself to operate. When the timer settings are such that the lamp should turn on, the power will then also be connected to the red wire by the timer and the light will turn on

At the lamp end in the lamp fitting there may be either 3 or 2 cables connected depending on where it is located in the light power wiring multiple run.

Scenario 1 - 3 cables connected:

All 3 black wires will be terminated on the same spare connector in the lamp terminal strip.

2 White wires will be connected to one lamp terminal and 1 white wire will be connected to the other lamp terminal.

The cable which has the single white wire connection in the lamp is the switch cable. The other two cables are the house light multiple wiring cables.

Find the earth wire in the switch cable and check that it isn't connected to anything. If it isn't connect it to the other 2 white wires i.e. you will now have 3 black wires connected together on the one terminal point, 2 white wires plus the switch cable earth wire connected together on one lamp terminal connector and the single white wire on the other lamp terminal.

Scenario 2 - 2 cables connected;

2 black wires will be terminated on the same spare connector in the lamp terminal strip.

One white wire will be connected to a lamp terminal connection and the other white wire will be connected to the other lamp terminal connection.

This scenario is harder because you have to trace the cables to see which cable goes down to the switch and which cable goes to another light fitting as it is the end of the wiring multiple.

Once you have determined which is the switch cable find the earth wire in the switch cable and check that it isn't connected to anything. If it isn't connect it to the other white wire i.e. not the white wire that is in the switch cable but the white wire that is in the other cable i.e. you will now have 2 black wires connected together on the one terminal point, 1 white wire plus the switch cable earth wire connected together on one lamp terminal connector and the single switch cable white wire on the other lamp terminal.