Concern over mains tester results

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Recently bought a house .Was up in loft putting down insulation when I noticed that what I believe is a 20amp 4 terminal junction box had a twin and earth cable coming out which was about a metre long and sealed off with insulation tape ie not attached to anything.

Down in the kitchen is a 2 gang light switch but while one switch puts on lights above the kitchen cabinets the other appeared to do nothing. It,s practically impossible to trace the cabling from the light switch into the loft but my guess was that a cable from the " spare " light switch ran into the terminal box and therefore swiched power on and off to the spare cable in the loft.

I had wanted to put a couple of downlights in the kitchen ceiling and this spare cable seemed to be the answer to my prayers.

Inside the juction box there are four connection in a straight row which for simplicity I will call 1,2,3,4 . In the top one ie terminal 1 there is a red feed from a two core cable and also in that same connection are two other reds both from three core cable .

In connector 2 there is a black from one of the three core cables which has the red attached to terminal 1 and also in that same no 2 terminal is a red from the spare 3 core cable.

Terminal 3 has nothing connected.

Terminal 4 has three blacks ie one from the " spare cable and one from each of the other two cables ie the 2 core and one of the tree cores with the red plumbed into terminal 1.

Using a mains tester I established that terminal 1 is permanently live.

Terminal 2 only shows as live when I switch on the previously redundant second switch on the light switch down in the kitchen.

Terminal 4 shows not live on the tester.

The earth wires from the two three core cables were both fed into a connection on a connector block outside the box but the earth wire from the spare cable wasn't connected to anything.

I had a 30 amp 3 terminal junction box and some three core ie twin and earth 1.5mm cable .

Having swiched off at the mains and pulled out the fuses I stripped the sealed end of the "spare cable ie the one already wired into the existing junction box and attached the red to the same terminal in the new junction box as a red/brown from each of the three spot lights ( not low voltage) did the same with the blues ie attached them to the second terminal in the new junction box as the black from the existing "spare" cable.


The earh wires were all connected together and fed into the third terminal on the new juction box. Switched on at the previously redundant switch downstairs and the new spots all came on ok. Being extremely cautious I touched the metal support leg attached to each of the lights with the mains tester and found to my horror that the red light on the mains tester came on with each one

Having bought the house I then became redundant as is my wife so we simply can't afford to call in the professionals, Can anyone help by suggesting what is wrong. I presume I should not be getting a red light on the tester when I touch the light supports so I won't be switching the lights on again until I can get some expert help. If I can't get any on here then I will just disconnect the " spare cable from the existing junction box and shut everything up and make do with no downlights.

Wife won't be happy but at least we will be alive .

Can anyone out there help?


:oops:
 
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Did you recconnect the earth which you found disconnected in the existing joint box?
 
That "2 core" cable should have an earth - it's very wrong and very worrying that it does not, because it's the loop cable, so that means that part of your lighting circuit is unearthed.


It,s practically impossible to trace the cabling from the light switch into the loft but my guess was that a cable from the " spare " light switch ran into the terminal box and therefore swiched power on and off to the spare cable in the loft.
Doing electrical design and installation work on the basis of guesses is unwise.


In the top one ie terminal 1 there is a red feed from a two core cable and also in that same connection are two other reds both from three core cable .
The cables with their blacks in T4 are the loop, the other cable drops down to that switch.


In connector 2 there is a black from one of the three core cables which has the red attached to terminal 1 and also in that same no 2 terminal is a red from the spare 3 core cable.
The black is the switched live returning from that switch - it should be sleeved red.


Terminal 3 has nothing connected.
That's where all the earths should be. They make 4 terminal JBs specifically for lighting circuits - Live/Switched Live/Neutral/Earth.

Look at the diagrams in the Wiki - //www.diynot.com/wiki/electrics:lighting - that JB works just like a ceiling rose, which also has 4 terminals.


Terminal 4 has three blacks ie one from the " spare cable and one from each of the other two cables ie the 2 core and one of the tree cores with the red plumbed into terminal 1.
The neutral for the loop and the light(s) supplied from that JB.


The earth wires from the two three core cables were both fed into a connection on a connector block outside the box but the earth wire from the spare cable wasn't connected to anything.
That's also not right - the earth from that cable must be connected to all of the others.


Being extremely cautious I touched the metal support leg attached to each of the lights with the mains tester and found to my horror that the red light on the mains tester came on with each one.
Those testers are useless - you can make some of them light up by rubbing them on a jumper.

You should get a proper multimeter.

And you must connect all the earths together, including the one from the cable running from the original JB to the new one and the one that (hopefully) is in the cable you're calling "2 core".
 
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Just a quick note to acknowledge, with thanks the replies I have had.

Going out this morning to help a friend whose car has broken down, so will read the replies when I come back later hopefully I'll find the answers I need there.

(don't worry it's not an electrical fault the car has).
 

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