replacing wall lights in lounge

rockyboy2

Novice Member
I have purchased three new wall lights and something has gone wrong with the wiring. Two of the lights have 2 of each wire black red and neuutra lthe other only has one of each wire coming from the wall. The new lights have only one terminal block with three conections live neutral and earth. I connected the two live red to the live brown, the two black to the neutral and the two earth to the earth terminal when I turn on the switch it trips the fuse box. I have a feeling that one of the black wires is a switch live should this be connected to the liveterminal? The lights are from searchlite milanese doubles any advice appreciated
 

outoftheknow

Moderator
The lights have red, black and earth. So the wiring out the wall is different? That isn't something going wrong. Only you know what light switches were connected to each light. That is why the wiring is different.

A light has a switched live and neutral (and earth for casing as or if required) and if only one light is on the one switch, you connect the live (switched) out the wall to the live on the light. Neutral to neutral and earth to earth (brass casing so earthed for yours).

A light bulb needs a switched live and neutral (and the earth for the metal casing). It can't have a constant live or it would be on all the time.

If it has a switched neutral it is dangerous as the fuse or other safety device will not cut the live power.

If one switch does two lights or two switches do one or two lights the wiring is different. When you removed the existing lights you could/should have taken a photo or drawn the connections.

Any details as to what the three lights did before? Number of switches per light, dimmers, and so on?
 

outoftheknow

Moderator
all three lights work from dimmer switch
Sorry you may need to be a bit more descriptive.

Three lights one dimmer switch?

Three lights two dimmer switch?

Or?
 
Last edited:

outoftheknow

Moderator
Also when you say fuse do you mean an MCB or an RCCB? Former is high current and latter is leakage to earth.

MCB is a single switch for a single circuit that replaces an old fashioned fuse.

RCCB will protect a section - I left the UK 11 years ago and I think rules have changed. Didn't used to put lights on an RCCB but I think now you do...

I suspect you mean an MCB?

Did the lights you removed have three connections?

Are the lamps the same technology as before and dimmable?

Are those two reds/lives in the wall photo twisted or were they seperate and you twisted them?

If same colour wires from the wall were twisted together when removed so there were three connections to each light as you describe you put back, you likely have a fault in connections or wire insulation somewhere.

If wires were seperate on any light and you twisted them together - that's your problem right there :)
 

rockyboy2

Novice Member
sorry I did twist them together,, same technoligy as before but were connected with a seperate connection block .The main fuse box is modern had it fitted two years ago rcb protected seperate switches for each circuit. The company I bought the new lights from said they were dimmable as long as I fitted the correct golf ball halogen lamps. The first light I took down only had one of each wire so I thought it would have been simple. Should have paid more attention to set up on others. Thanks for all your help so far. I guess because I only have my pension to live on I cant really afford to hire tradespeople all the time. I am a retired carpenter and I did a two week course on basic electrics some years ago.
 

outoftheknow

Moderator
Apologies you lost me again.

The lights you removed had three connections on their blocks like the new ones or four or...?

The red wires out of the wall were twisted together or not on removal of each fitting?

The black wires out of the wall were twisted together or not on removal of each fitting?

One dimmer switch to three fittings before and after?

Same technology but new only dimmable if halogens fitted?

What was the technology of old bulbs and what are new ones?

Is a residual current breaker tripping or a miniature circuit breaker?
 

neilball

Well-known Member
How many cables are at your switch and is there only one switch for the circuit?

You need to find out if the supply for the circuit comes via the switch or whether it is fed from the first fitting on that circuit. Once you know that you need to trace and label your existing cables. With the POWER OFF you should be able to trace the cable linking the last fitting the the middle fitting, then trace the second cable at the middle fitting back to the first fitting, then work out which is the switch cable and feed cable. Use a meter with continuity tester to trace and label each cable methodically one at a time and you should hopefully get it worked out.

I would then wire up the first fitting on the circuit with a regular switch and test it works ok. If it does then test again with your dimmer. This ensures that there are no faults with he new fitting or dimmer. Then wire in the next fitting and test again. That way you will find out if any of your new kit is faulty.
 

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