DIY How To

One way lighting loop in method

Most modern lighting installations use the loop in method for connecting up one way lighting circuits. Modern ceiling roses are designed to facilitate this method of wiring. The advantages of the loop in method is all the connections are accessible and can easily be inspected and maintained as per the current electrical regulations.

One way lighting circuit using loop in ceiling roses

Line diagram of a one way lighting circuit using loop in ceiling roses (fig 1).

One way lighting circuit using loop in ceiling roses fig 1

The ceiling rose should be wired as shown below.

Loop in ceiling rose fig 2

Explanation of above picture. (fig 2)
The feed cable comes from a previous ceiling rose or from the consumer unit, the red wire is connected to the middle terminal block (Loop In), the black wire is connected to the same terminal block as the blue wire going to the lampholder (Neutral) and the earth wire is connected to the earth terminal. The earth wire must be covered with green/yellow sleeving.

The cable going to the light switch is connected as follows (fig 2). The red wire going to the light switch is connected to the same terminal (Loop In) as the red wire from the feed cable, the black wire coming back from the switch is connected to the same terminal as the brown wire going to the lampholder (Live) and the earth wire is connected to the same terminal as the earth wire from the feed cable.
The black wire from the light switch, should be marked with red tape or red sleeving to show it is a live wire, but in practice is often left unmarked.

 

The following picture is exactly the same as the picture above with the addition of another cable which provides the feed for the next ceiling rose.

Loop In ceiling rose fig 3

The cable going to the next ceiling rose is connected as follows (fig 3). The red wire going to the next ceiling rose is connected to the same terminal as the red wire from the feed cable, the black wire going to the next ceiling rose is connected to the same terminal as the black wire from the feed cable and the earth wire going to the next ceiling rose is connected to the same terminal as the earth wire from the feed cable.

 

A one way light switch is quite easy to wire up.

One way light switch fig 4

The cable going to the light switch is connected as follows (fig 4). The red wire is connected to the top terminal, the black wire is connected to the bottom terminal and the earth wire is connected to the earth terminal.

If you are using a plastic switch the earth wire will need to be connected to the terminal in the terminal box (as shown above) because there are no earth terminals on plastic light switches.

A two way light switch can also be used in in place of a one way light switch, in this instance the red wire is connected to the common (C) terminal and the black wire is connected to the (L1) terminal. The (L2) terminal is unused.

 

A metal light switch must be earthed as seen below.

Metal light switch fig 5

Safety AdviceIf you are using metal light switches (fig 5) make sure you connect the earth wire to the earth terminal on the switch and fit an earth link wire from the switch to the earth terminal in the back box.

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