Loop in method for Lighting Circuits

Conventionally with the 3 plate system, all reds were connected together at the ceiling rose at the centre terminal block with three terminals.  Red 1. Line supply....... Red. 2 Line looped out to next ceiling rose......Red 3 Dropped down to room light switch, normally in a T&E cable.


The black from the light switch was marked with red tape or red sleeving if you are lucky. This becomes the lamp holder line, or ceiling light line.


The black of the supply T&E is neutral and connects to the ceiling rose terminal with three terminals marked neutral, or at  one side of the three separate connectors.


The loop cable to the next ceiling rose connects its red to the centre terminal, (permanent line). Its black core connects to the neutral terminal using the second screw position.


The red from the switch (switched line) connects to the last outer terminal of the ceiling rose the terminal with just two screws.


The lamp holder connects to the two extreme outer terminal positions at the ceiling rose, switched line and neutral.


If you have just a load of wires hanging from the ceiling at the light position and the system is three plate wired, and you wish to terminate the wires correctly, just find the switch drop first. You could use a buzzer or a meter with a continuity buzzer facility or an Ohm meter. Just connect the meter leads to any pair of  red and black wires at the light position with the light switch on. When you hear the buzzer you have found the switch drop cable. When the switch is turned off continuity is lost and the buzzer will stop buzzing or continuity will show infinity Ohms. This confirms the switch drop cable.  Mark it accordingly and sleeve the black wire brown. All other wires are then easily terminated at the ceiling rose, their positions being obvious.


Z.

Conventionally with the 3 plate system, all reds were connected together at the ceiling rose at the centre terminal block with three terminals.  Red 1. Line supply....... Red. 2 Line looped out to next ceiling rose......Red 3 Dropped down to room light switch, normally in a T&E cable.


The black from the light switch was marked with red tape or red sleeving if you are lucky. This becomes the lamp holder line, or ceiling light line.


The black of the supply T&E is neutral and connects to the ceiling rose terminal with three terminals marked neutral, or at  one side of the three separate connectors.


The loop cable to the next ceiling rose connects its red to the centre terminal, (permanent line). Its black core connects to the neutral terminal using the second screw position.


The red from the switch (switched line) connects to the last outer terminal of the ceiling rose the terminal with just two screws.


The lamp holder connects to the two extreme outer terminal positions at the ceiling rose, switched line and neutral.


If you have just a load of wires hanging from the ceiling at the light position and the system is three plate wired, and you wish to terminate the wires correctly, just find the switch drop first. You could use a buzzer or a meter with a continuity buzzer facility or an Ohm meter. Just connect the meter leads to any pair of  red and black wires at the light position with the light switch on. When you hear the buzzer you have found the switch drop cable. When the switch is turned off continuity is lost and the buzzer will stop buzzing or continuity will show infinity Ohms. This confirms the switch drop cable.  Mark it accordingly and sleeve the black wire brown. All other wires are then easily terminated at the ceiling rose, their positions being obvious.


Z.