Light Stays on after Change Fitting and Copying Existing Wiring Setup?


Postby cjdunn » Wed Aug 12, 2015 8:52 pm

New fitting.jpg
New Fitting
Hope someone can help on this.
I removed an old simple light fitting and took a photo before removing
I replaced it with the new one shown
I copied the wiring but there was an earth lead on the new fitting.
First I connected this to the middle block but light stayed on. I removed it but still stays on
Now I have put the old fitting back but still stays on!!
Made it worse, doh!

Thanks in advance
Chris
Attachments
Removed new fitting.jpg
Removed new fitting
Before.jpg
Old fitting
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Postby ericmark » Fri Aug 14, 2015 5:56 am

Looking at pictures can't see why it would not turn off so I suspect a fault with the switch.

It is wired incorrectly the earth wires should go to clamp and the red wires in the chock block should have been in the centre but this should not have affected it working.

The normal method is to use a small junction box in the ceiling space and reduce the three cables to one. You have power in, power out to next light, and switch cable the latter has the red tape on the line from switch.

The British method of using a ceiling rose as a junction box has many advantages. It reduced the amount of cable so reduces volt drop, it provides a permanent line for emergency lights and ceiling fans, However the Continental method of using the switch as a junction box means less wires at the ceiling rose and some houses now have this method mainly in the 1990's when there was a move to silly spot lights in the ceiling which had not option to use the terminal block as a junction for cables.

There was a lot of people who would used terminal strip without putting it in a box to convert to a single wire. However there have been accidents where people have reached under floor boards and touched these blocks.

The maintenance free junction box seems the favourite way to convert three cables to one as they have cable clamps in the box. But in real terms they are a pain to fit as often there is not the room to work with and I have needed either to cut a larger hole in ceiling and make good or lift floor boards.

In theroy insulation tape joints are not allowed because the tape can be removed without a tool. However you need to use some common sense and if from above one is unlikely to be able to touch live wires then using tape I would say is OK.

But returning to pictures I would expect to find switch has failed and would tape that block with the three red wires so from above unlikely anyone working under the floor boards will touch line wire.

P.S. Live = Neutral and Phase wire.
Line = Phase wire.
This is convention as with TT earthing system the neutral can have a high voltage.
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Postby cjdunn » Sat Aug 15, 2015 11:32 am

Thanks for your reply Eric
Just need to clarify the wiring on the new fitting. I couldn't fit the circlular block in so I cut it as shown.
The block has Line, Loop and N
Is the red taped black wire in Line correct or should go in other slot

In my old fitting, which worked, the yellow/green cable was in Loop so should that be in the Earth pin at the top of the pic.
BW
Chris
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Postby ericmark » Sun Aug 16, 2015 5:08 am

[quote="cjdunn"]Thanks for your reply Eric
Just need to clarify the wiring on the new fitting. I couldn't fit the circlular block in so I cut it as shown.
The block has Line, Loop and N
[/quote]Line is the new word for live, it was decided that neutral should be classed as a live wire so needed a new word for the phase wire and calling it line means it still makes sense where "L" is used. In your case it is really the switched line. Loop is the word used for permanent line it refers to the line looping from lamp to lamp. N is for the neutral.[quote="cjdunn"]
Is the red taped black wire in Line correct or should go in other slot
[/quote]Yes this is correct this is the switched line wire.[quote="cjdunn"]
In my old fitting, which worked, the yellow/green cable was in Loop so should that be in the Earth pin at the top of the pic.
BW
Chris[/quote]
The earths should be under the clamp, Although it does not really matter how they are connected as long as they are.

You have three cables at the light.
1) Live supply.
2) Supply to next lamp.
3) To the switch.
All reds go together.
All earths (bare wires) go together.
But only two of the blacks go together they are the neutrals the third black with red tape it the switched live from the switch and you need to be careful not to lose that marking.

Many lamps don't have terminals for the loop wires and it is common to see them in a bit of terminal block as with yours. I will guess some one had a fancy light there before and it has been swapped back to standard ceiling rose. For some reason council houses have all fancy lamps stripped out before re-letting I will guess something similar has gone on. And I will guess the electrician knows jolly well the ceiling rose will be removed again so has left the reds in the connector block to make it easy for you.

As I said I can't see any reason why it would not work. It may not be the normal method but it should still work.

What I have found in the past is people in error have put that black wire with red tape on it with the other black wires which causes a direct short. This has blown the switch so no amount of wiring permutations can then get it working again.
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