Light fitting loop connection - Advice please!

[sandybeachit]

Well done, too many people try and approach lighting in a "painting by numbers" manner.

A switch works by interrupting the live feed to a light. If you were wiring with single wires, you would take the permanent live to the switches, the neutrals to the lights and then take a switched live wire from each switch to the corresponding light.

But while single wires in conduit or double insulated single wires are legitimate installation methods, most of the time in the UK (other countries may vary) we don't use single wires, we use cables. There are a few common arrangements for wiring lights with cables:

1. The "loop at light" method, "circuit cables" carrying permanent live and neutral are routed to the lights, then a "switch cable" takes permanent live down to the switch and brings switched live back.
2. the "loop at switch" method, "circuit cables" carrying permanent live and neutral are routed to the switches, then a "cable to lighting point", takes switched live and neutral to the light.
3. the "junction box" method, "circuit cables" carrying permanent live and neutral are routed to junction boxes, then a "switch cable" takes permanent live down to the switch and brings switched live back and finally a "cable to lighting point", takes switched live and neutral to the light.

With the loop at light method the permanent live conductor is joined at the light fitting location, but does not actually connect to the light. Similarly with the loop at switch method, the neutral is joined at the switch location but does not actually connect to the switch.

"twin brown and earth" ("twin red an earth" on older installations) cable does exist, but most installers don't want to carry an extra roll of cable if they don't have to, and it's sometimes useful to be able to distinguish permanent live from switched live. So most of the time regular twin and earth is used for switch drops. The switched-live should be marked with brown (red on older installations) sleeving but often isn't.

Traditional UK ceiling roses and batten holders usually have a built-in "loop" terminal, which is used to join the permanent live conductors together. With other types of fitting sometimes the manufacturer provides a loop terminal, but often they don't. So you often have to provide a suitable terminal yourself, or in extreme cases even convert the setup to a junction box setup.

Finally it's important to remember those that these methods are not the be-all and end-all of lighting wiring, there are countless possible combinations and variants of the basic methods. This is why we *always* advise people to carefully record the existing wiring before dismantling.

Awesome thanks, right that is certainly helping my knowledge!

 

[sandybeachit]

Just so that you are aware, as I said, one of those loop cables runs down to the light switch, the return path, which is the blue cable with the brown sleeving is the switch live. ie it only become live when the light switch in the on position.

There are two lights in my hallway, one has a cable in the loop (out of the three), the other light has no cables going to the loop.

So does this mean I must have a loop cable connected somehow so the light switch will turn the light on and off?

If this is the case I am at a loss as to how to do this, as if I terminate the loop cables surely what your saying won't happen and the light switch won't turn the lights on or off?

 

[johnny2007]

Don't stuff 2 wires in the same hole = Some like that sort of thing lol!

Ok dumb question, now I get what you mean by one cable one connector hole.

What happens if you put two cables in one hole, will it short the circuit? I am guessing that or an electrical fire etc, I would like to know what could go wrong.

I have zero electrical knowledge so I am finding this an interesting DIY project.

If you have 1mm2 wires, you might be successful at putting 2 of them in a wago hole, but why would you???
Wagos are sold in 2,3,4,5,6 and even 8 "holes" (terminal) combination.
Just use the correct one, in your case, a 2 terminals block.

 

[sandybeachit]

If you have 1mm2 wires, you might be successful at putting 2 of them in a wago hole, but why would you???
Wagos are sold in 2,3,4,5,6 and even 8 "holes" (terminal) combination.
Just use the correct one, in your case, a 2 terminals block.

Thanks will do, one previous person mentioned how the loop goes back to the switch to help turning it on or off, I think I misunderstood somehow, but once I terminate the loop the light switches will still work to turn the lights on and off again?

 

[opps]

Don't stuff 2 wires in the same hole = Some like that sort of thing lol!

Ok dumb question, now I get what you mean by one cable one connector hole.

What happens if you put two cables in one hole, will it short the circuit? I am guessing that or an electrical fire etc, I would like to know what could go wrong.

I have zero electrical knowledge so I am finding this an interesting DIY project.

You wouldn't be able to push two 1.5mm cables in to the same hole in (an appropriately sized) Wago.

At the risk of over simplifying things, electrical fires are often the result of too much current running through a cable. A lose connection will arc though and melt the connection/cable. If you marry up cables incorrectly, I would expect the MCB in the consumer unit to trip (note: the worst you could do though is to mix the earth and permanent lives. That would a make the flight fitting become live. If you are on an RCD, I believe that any contact between the earth and live would trip the RCD i the consumer unit.

 

[SUNRAY]

There are two lights in my hallway, one has a cable in the loop (out of the three), the other light has no cables going to the loop.

So does this mean I must have a loop cable connected somehow so the light switch will turn the light on and off?

If this is the case I am at a loss as to how to do this, as if I terminate the loop cables surely what your saying won't happen and the light switch won't turn the lights on or off?

This is the basis of how a switch and a light work:

Somewhere in the system We need to bring the supply, the switch and the light together and that is conveniently done at the light fitting (ceiling rose):

As we don't tend to use cable with 2 browns (or 2 reds), instead we use brown and blue and add marker sleeves to the blue:

Does this help explain how it works?


If both of your hall lights work together (by the same switch) the common method is adding a link between the 2 lights:

Leaving the 'loop' terminal empty in the second light.

 

[sandybeachit]

This is the basis of how a switch and a light work:
View attachment 272790
Somewhere in the system We need to bring the supply, the switch and the light together and that is conveniently done at the light fitting (ceiling rose):
View attachment 272791

As we don't tend to use cable with 2 browns (or 2 reds), instead we use brown and blue and add marker sleeves to the blue:
View attachment 272793
Does this help explain how it works?


If both of your hall lights work together (by the same switch) the common method is adding a link between the 2 lights:
View attachment 272795
Leaving the 'loop' terminal empty in the second light.

Ok yes I think I am starting to understand how this loop system works. I had never came across this until I look at my light setting in my current property.

 

[terryplumb]

There are two lights in my hallway, one has a cable in the loop (out of the three), the other light has no cables going to the loop.

So does this mean I must have a loop cable connected somehow so the light switch will turn the light on and off?

If this is the case I am at a loss as to how to do this, as if I terminate the loop cables surely what your saying won't happen and the light switch won't turn the lights on or off?

Are your two hallway lights operated by the same switch ?

 

[terryplumb]

There are two lights in my hallway, one has a cable in the loop (out of the three), the other light has no cables going to the loop.

So does this mean I must have a loop cable connected somehow so the light switch will turn the light on and off?

If this is the case I am at a loss as to how to do this, as if I terminate the loop cables surely what your saying won't happen and the light switch won't turn the lights on or off?

Are your two hallway lights operated by the same switch ?

 

[sandybeachit]

This is the basis of how a switch and a light work:
View attachment 272790
Somewhere in the system We need to bring the supply, the switch and the light together and that is conveniently done at the light fitting (ceiling rose):
View attachment 272791

As we don't tend to use cable with 2 browns (or 2 reds), instead we use brown and blue and add marker sleeves to the blue:
View attachment 272793
Does this help explain how it works?


If both of your hall lights work together (by the same switch) the common method is adding a link between the 2 lights:
View attachment 272795
Leaving the 'loop' terminal empty in the second light.

Yes My hall has 2 light fittings with one switch, same in my living room 2 lights for one switch so this explains how the lights are linked up.

My only concern is in my new fitting I only have the live and neutral so I know I have to terminal the loop cables which I know how to do thanks to everyone here.

Will be terminating the loop cables not interfere with how everything works? As from your diagrams the loop helps with the switch so if I don't use the loop cables will everything be fine or am I going to have issues?

This is what is confusing me about the loop, it seems like I can terminate them and not use them and it has no effect, but since they are in place they must have a use? So am I ok to just terminate and not use them without any consequences?

 

[sandybeachit]

Are your two hallway lights operated by the same switch ?

Yes

 

[SUNRAY]

This is what is confusing me about the loop, it seems like I can terminate them and not use them and it has no effect, but since they are in place they must have a use? So am I ok to just terminate and not use them without any consequences?

If you look at the bit in the red circle

there are simply 2 wires joined together which corresponds to the red circle here:

The pink circle being the 'L' terminal in the ceiling rose and the grey is the 'N'