new light fitting blowing breaker

[kyranocat]

hi guys hoping to get some advice, our porch light has been removed as the entire porch is being redone but the 2 cable feeds were not identified i have checked polarity on one and i am certain this is the switch wire leaving the second cable as a mains feed cable .The problem is every time i wire a light onto these cables the circuit breaker trips as soon as the light switch is clicked into the on position.I am lost on what the issue might be.Polarity has been confirmed on the switch wire so thats correct and the mains cable turns live then the breaker is in the on position aswell.I dont think its an overloaded circuit either as both lights are the same wattage and even tried wiring the old light back on to check (SAME SITUATION OCCURS).
I am hoping someone might be able to shed some light on the situation(no pun intended).Thanks

 

[telectrix]

switch L connected to N. recheck which cable is which.

 

[TaffyDuck]

Sounds like there is a direct connection between live and neutral thus an open circuit hence the mcb breaking. Check that you have the cables identified properly. You`ve probably got the switched live, (normally not the red/brown) conected directly to the neutral

 

[kyranocat]

have checked switched live is connected to the live on the rose its wired correctly i made sure of that tested with volt indicator between L AND N whilst flipping switch to get closed and open circuit.As soon as the live conductor on the mains feed in is connected to the loop block it blows

 

[Octopus]

You've got your feed, loop and switch mixed up.

What equipment do you have to hand to test the cables?

 

[telectrix]

reminds me od dick emery. "dad' iv'e got it wrong again"

 

[kyranocat]

ive only got a voltage/polarity indicator at hand.

1.I have identified the switched live by opening/closing switch and testing between live and neutral of the cable on the light side of the cables.
2.I have connected the switched live(neutral with brown sleeve) to switched live.
3.remainder neutral are connected to neutral block.
4.remainder lives connected to Loop Block.

 

[kyranocat]

ive only got a voltage/polarity indicator at hand.

1.I have identified the switched live by opening/closing switch and testing between live and neutral of the cable at the light side.
2.I have connected the switched live(neutral with brown sleeve) to switched live.
3.remainder neutral are connected to neutral block.
4.remainder lives connected to Loop Block.

 

[TaffyDuck]

Well mate unless you`ve damaged a cable with a screw or something you`ve done what we have said.

 

[kyranocat]

thats the problem i cant think of anything else being an issue i will go back tomorrow and try again maybe im thicker on the weekends or something but to me it all makes sense and seems fine i checked polarity on the switch cable a million times to just make sure i wasnt going nuts or anything.

 

[TaffyDuck]

Is there an RCD and if there is. is it tripping?

 

[Octopus]

thats the problem i cant think of anything else being an issue i will go back tomorrow

Hum, so are you another of these nuts who's pretending to do electrics without a tester?????

 

[ample current]

ive only got a voltage/polarity indicator at hand.

1.I have identified the switched live by opening/closing switch and testing between live and neutral of the cable at the light side.
2.I have connected the switched live(neutral with brown sleeve) to switched live.
3.remainder neutral are connected to neutral block.
4.remainder lives connected to Loop Block.

The conductor with the blue insulation and brown sleeve should go to the live of the lamp the other
conductor of the same cable should be in the live loop and the second cable the brown to live loop and the blue to the neutral of the lamp

 

[kyranocat]

yes rcd is tripping

 

[kyranocat]

yes ample current it is wired exactly as you have described

 

[TaffyDuck]

yes rcd is tripping[/QUOTE

fault current

If the switch is recessed into a metal box check that the set pins on the switch have not knicked the live inside the switch

 

[rich.250]

Rcd and or mcb?

 

[telectrix]

"cut the blue wire".

 

[TaffyDuck]

"cut the blue wire".

Hurt locker?

 

[telectrix]

richard harris in the film juggernaut. unexpolded bomb.

 

[ample current]

you are going to have to test the circuit then with an mft then to identify the fault.

 

[telectrix]

i'll lend out my neon screwdriver for a modest fee.

 

[TaffyDuck]

i'll lend out my neon screwdriver for a modest fee.

Nice one, I just use my finger, if it hurts its live

 

[kyranocat]

i was suspicious about if i had correctly identified the switch so on top of using a continuity/polarity indicator i have nicked a MFT from someone to test the continuity and it does confirm its the switch wire. got a reading and then flipped the switch to get an open circuit so i am going to try testing the circuit more indepth later in the week.I am wondering if i should try and replace the switch to see if its the issue, will post back later with an update.

 

[trev]

Nice one, I just use my finger, if it hurts its live

You big jessie
Get your tongue on it. It's the only way to test live/dead
YYYYYYYEEEEEEEEEEEEEEEEEHHHHHHAAAAAA

 

[ample current]

not sure if this would be considered good practice, but have you tried connecting the incomming live and neutral to the lamp connectors directly missing out the switch and switch wire altogether to see if that trips the breaker.

 

[Hawk81]

Is this your own porch or not? If its wired in new colours it not that old a wiring then. I take it all was ok before the light was removed?

 

[Knobhead]

I’m sorry but two cables doesn’t give a lot of options.
If you’ve borrowed a MFT do you know how to use it?
A competent electrician will find the fault within ¼ hour.
If building modifications have been done the chance is cable damage!