Problem replacing pull chord switch in bathroom

[jonesie]

Untitled

• jonesie
• 8 Mar 2015
• 1

Untitled

• jonesie
• 8 Mar 2015
• 1

Top one is for the pull chord
Bottom is for the light, blacks together and reds together, I know now that this is incorrect,
No markings on the black wires, yes I have had to make alternative fixings to the ceiling, just screwed straight into the joist, pretty certain I haven't gone through any wiring

 

[bernardgreen]

One red is the permanent LIVE from the consumer unit ( fuse box ) The black in this cable is the NEUTRAL from the consumer unit.

The other red takes the permanent LIVE to the switch. When the switch is ON the LIVE is connected to the black wire in that cable. Thus this black is NOT a NEUTRAL. it is Switched LIVE and should have red sleeve to mark it as switched LIVE

The lamp requires the Neutral and the Switched Live.

So connect the two reds together in a separate terminal block.

DO NOT connect the two blacks together.

Connect one black to one side of the lamp and the other side of the lamp.

As you only have two cables and not a third cable to another lamp in another room it will work ( and switch on and off ) not matter which black goes to which side of the lamp.


You may find the switch will not operate properly as, with the two blacks joined together the switch shorted Live to Neutral which tripped the MCB. That short may have damaged the switch contacts

 

[PrenticeBoyofDerry]

Yes you have shorted the circuit out.
As you were with pull cord, problem is with light fitting
Two reds in separate live loop, not connected to any of the terminals of the lamp. Then you are left with two blacks, one will be a neutral and the second comes live when switch is in the on position. To Identify which is which you will require to use some test equipment by either measuring continuity or voltage. But in a standard light fitting reverse polarity at the two lamp terminals would still allow it to work, on certain fittings it would be wise, as a safety precaution to wire it correctly though!

 

[jonesie]

Bernard,so what you are saying if I've understood you correctly is this,
I connect the two reds together in a block connecter, then connect the TWO black wires to the light unit, and it won't matter which terminal ie live or neutral that I connect them to? I'm a bit thick when it comes to lighting

 

[PrenticeBoyofDerry]

Bernard,so what you are saying if I've understood you correctly is this,
I connect the two reds together in a block connecter, then connect the TWO black wires to the light unit, and it won't matter which terminal ie live or neutral that I connect them to? I'm a bit thick when it comes to lighting

It really depends on the type of fitting you have.

 

[bernardgreen]

I connect the two reds together in a block connecter, then connect the TWO black wires to the light unit, and it won't matter which terminal ie live or neutral that I connect them to? I'm a bit thick when it comes to lighting

One black to one terminal of the fitting and the other black to the other terminal of the fitting. The two blacks must NOT go to the same terminal,

 

[jonesie]

Yeah got it Bernard, many thanks for the help everyone

 

[PrenticeBoyofDerry]

If the lampholder is a Edison screw type, it would be best/safe practise to have the switch live in the live terminal.

 

[jonesie]

It is a screw type yes, how do I find out which is the switch live mate? I have one of those little screw drivers that can test for current! Will this suffice?

 

[PrenticeBoyofDerry]

The screwdriver testers are not something that is considered as safe or reliable as a test instrument. A two pole voltage indicator would be more appropriate.

 

[flyingsparks]

If the lampholder is a Edison screw type, it would be best/safe practise to have the switch live in the live terminal.

Not just 'best/safe practice' but against the regs not too....

 

[PrenticeBoyofDerry]

If the lampholder is a Edison screw type, it would be best/safe practise to have the switch live in the live terminal.

Not just 'best/safe practice' but against the regs not too....

Indeed, I thought I was struggling to get my messages across to the OP or they were being ignored, so didn't elaborate too much.

 

[ban-all-sheds]

Aragorn84, yes you are correct, I did put the blacks together at the light fitting! I take it that this is the problem? How do I rectify it?

Get a time machine, go back to before the point where you decided that it would be perfectly OK for you to fiddle with your wiring even though you didn't actually understand how it works, and revisit that decision.

 

[sparkwright]

You must have the switch live in the live terminal
and
the neutral in the neutral terminal.

If there's any doubt, perhaps there's a loft above so you could trace the wiring to make sure it's correct.

 

[sparkwright]

The screwdriver testers are not something that is considered as safe or reliable as a test instrument. A two pole voltage indicator would be more appropriate.

Good enough in this case just to give an indication which is the switched live though, wouldn't you say?

Or not?