Wiring For Light - Two Red Wires & Earth

[pbar]

We have 5 wall lights, and the decorator has taken them all off, and just left terminal blocks on temporarily.

Four of them are ok, but one of the cables consists on two red wires & earth.

I do not know now, which was previously connected to the live/neutral fitting of the light.

Does it in fact matter which goes where? Why are there two reds, will they both be live? They both actually do have red sleeving, and not just red sleeving slipped on.

All five lights are controlled by a two gang wall switch, one side of the switch controls two of the lights (on one wall) and the other switch controls the other three lights (on the opposite wall).

 

[sparkwright]

Are there other cables present at this wall light point?

If so, how many?
And how are the wires currently connected to the connector blocks?

Usually, a twin red cable implies a switch wire, consisting of a permanent live, and a switch return wire.

 

[PrenticeBoyofDerry]

This will be your switch wires they are both considered live that is why they are red core colours.
Your switch should work if it's a standard toggle/rocker switch with one red in com and the other in L1 or L2.
Ideally you would want the perm live in the com but you would need some test equipment to determine which is which.

 

[pbar]

Are there other cables present at this wall light point?

If so, how many?
And how are the wires currently connected to the connector blocks?

Usually, a twin red cable implies a switch wire, consisting of a permanent live, and a switch return wire.

No, there are no other wires present, each cable for each light is simply twin and earth, and it is just this one cable in question, which is two reds and earth.

Currently, in the connector block, both red wires are in separate terminals.

Previously, in the light fitting, one of the red wires was connected to the live terminal, and the other red to the neutral. But I do not know now, which was which, or if it matters...?

 

[pbar]

This will be your switch wires they are both considered live that is why they are red core colours.
Your switch should work if it's a standard toggle/rocker switch with one red in com and the other in L1 or L2.

The switch has not been touched, so it's as it was. It is the light fitting I am unsure about, as I do not know which of the two red wires go into the live and neutral connections.

 

[sparkwright]

Are there other cables present at this wall light point?

If so, how many?
And how are the wires currently connected to the connector blocks?

Usually, a twin red cable implies a switch wire, consisting of a permanent live, and a switch return wire.

No, there are no other wires present, each cable for each light is simply twin and earth, and it is just this one cable in question, which is two reds and earth.

If that's correct then the cable has been used incorrectly, though not a real problem. You need to test the cable to work out which is live and which is neutral. Sleeve the 'neutral' with a black sleeve.

Do you have a test meter?

 

[pbar]

Are there other cables present at this wall light point?

If so, how many?
And how are the wires currently connected to the connector blocks?

Usually, a twin red cable implies a switch wire, consisting of a permanent live, and a switch return wire.

No, there are no other wires present, each cable for each light is simply twin and earth, and it is just this one cable in question, which is two reds and earth.

If that's correct then the cable has been used incorrectly, though not a real problem. You need to test the cable to work out which is live and which is neutral. Sleeve the 'neutral' with a black sleeve.

Do you have a test meter?

I have no test meter, no.

 

[PrenticeBoyofDerry]

If it is at the light fitting someone has used the wrong cable as you should have a neutral conductor as well as a live.
Follow sparkwrights instructions, test for live conductor.
You need either a multi meter or a voltage indicator.

 

[pbar]

If I was to connect them up the wrong way round, would the fuse simply trip?

 

[PrenticeBoyofDerry]

If I was to connect them up the wrong way round, would the fuse simply trip?

Not good or safe practice, would not recommend it.

 

[pbar]

I assume that I could put a neon screwdriver into the terminal screw of the block and see it if lights? Though I don't really wish to use those.

Is there any other method of testing which is the live wire...?

 

[PrinceofDarkness]

pbar: most DIYers, such as yourself, use a 99 Pence neon screwdriver to identify the live connection.......

But if you don't have such a high-tech gadget, then you can test as follows: (Assuming this isn't an RCD protected circuit), use a lampholder and lamp borrowed from the nearest pendant ceiling rose - connect one wire of the flex to the earth connection and the other to either of those reds and switch on at the wall. Provided that the earth connection is sound, the lamp will light between earth and live - but not between earth and neutral.

Once you've established which red is the neutral, mark it (black) in some permanent way, for future tinkering.


Lucia.

 

[pbar]

pbar: most DIYers, such as yourself, use a 99 Pence neon screwdriver to identify the live connection.......

But if you don't have such a high-tech gadget, then you can test as follows: (Assuming this isn't an RCD protected circuit), use a lampholder and lamp borrowed from the nearest pendant ceiling rose - connect one wire of the flex to the earth connection and the other to either of those reds and switch on at the wall. Provided that the earth connection is sound, the lamp will light between earth and live - but not between earth and neutral.

Once you've established which red is the neutral, mark it (black) in some permanent way, for future tinkering.


Lucia.

Superb, I will try that method. Thanks very much.

 

[PrenticeBoyofDerry]

Lets hope you have earth continuity and the accessories ain't metal.

 

[PrinceofDarkness]

Derryboy: If he doesn't have earth continuity to that fitting, the test lamp will simply fail to light, won't it? And therefore, it wouldn't be possible for a significant fault to appear on those supposed metallic accessories, would it?

Do you have to be so guarded and politically correct when dealing with such DIYers as this O/P?


Lucia