Try and figure this one out!!!

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youngspark

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Im at the fuse board and there is a fault with one of the lighting circuits. Cut a long story short when the Live is in the breaker the neutral becomes live aswell.
So I presume its a short circuit, I isolate the power and test continuity between Live a Neutral (My tester is calibrated and I tested on a known source before hand) but there is no continuity between the two!!??
Has anyone.... I mean anyone!!! Got an explanation for this?
 
So, you have the line in the breaker and juiced up. Is the neutral dangling in fresh air when you measure the voltage, or in the neutral bar. Are any lights switched on?
 
sounds to me like you have lost your neutral if you have removed the neutral from the board then you will get 230volts on the neutral between the earth and neutral , not a very clever thing to do as you could electricute yourself if you touch it, to test it properly do an r1r2 test to ensure you have good continuity on the circuits then do an r2rn to ensure you have neutral continuity
 
so the N is dangling and there are 1 or more lights switched on. as the circuit is open circuit at the n END, then you will have 0 volt drop across the load, therefore you will get the line voltage on the N.
 
I was shocked as well (not literally) and that's what I thought about the polarity but it still doesn't explain why there is no continuity between the Line and Neutral conductors?
 
if all the lamps are low energy you may not get a direct continuity reading due to the electronics in the lamp, depends on the electronics of the lamp , i am asuming the light switches have been switched on
 
You're reading 240v through a lamp which, if it's say a 60W filament lamp will have a resistance approaching 1k ohm - too high for your continuity tester.
 
a filament lamp will read around 80 ohms cold. still too high for some continuity testers.
 
nickblake said:
sounds to me like you have lost your neutral if you have removed the neutral from the board then you will get 230volts on the neutral between the earth and neutral , not a very clever thing to do as you could electricute yourself if you touch it, to test it properly do an r1r2 test to ensure you have good continuity on the circuits then do an r2rn to ensure you have neutral continuity
Click to expand...

So even when I remove a neutral from a different circuit in the fuseboard and test between Earth and that neutral the voltage will still be 230v?
 
telectrix said:
so the N is dangling and there are 1 or more lights switched on. as the circuit is open circuit at the n END, then you will have 0 volt drop across the load, therefore you will get the line voltage on the N.
Click to expand...

Really helpful cheers telectrix, so if there is no load on the circuit (all of the lights are off) will there be any voltage at the neutral?
 
youngspark said:
So even when I remove a neutral from a different circuit in the fuseboard and test between Earth and that neutral the voltage will still be 230v?
Click to expand...


yes think about it like the lads have said you may not get continuity readings if the light switch is switched on breaker on , lamp in the holder then the 230 volt will run through the circuit back to the neutral bar hence making the circuit , if you disconnect the neutral then it stays positivly charged so you will have 230 volts on the neutral , like i said in my post you need to check the circuits continuity by using the r1r2 , r2 rn formual this will confirm polarity and continuity of the cpc , live and neural conductors
 
sorry mis read your post , dont go removing neutrals from other circuits with the power on you could end zapping your self if all your switches are off then you shouldnt get 230 volt on the neutral thats if you have the correct neutral or if you have a shared neutral you could end up with 230 volts , you could also get a lower voltage reading due to induced voltage
 
This has to be a college question if not this guy is dangerous. To be fair I did get a belt today off a borrowed neutral it was dead until my mate turned another lighting circuit on not the one I was working on and that's how we found it, and I must say it was a painful one. But this building had a periodic done 8 weeks ago and passed, me thinks they used the magic invisible test kit .
 
youngspark said:
I was shocked as well (not literally) and that's what I thought about the polarity but it still doesn't explain why there is no continuity between the Line and Neutral conductors?
Click to expand...

why would there be continuity between live and neutral ?
breaker would obviously trip :S
the neutral has no return path and has became live
 



y are you asking me this ?

i didnt start this thread

Confusion begins
icon7.png




Cross eyed judge to 3 cross eyed defendants
"No1 how do you plead"?
"Not guilty" said No2
"I didn't ask you" says the Judge ?
"I said nothing" said No 3
 
snowhead said:
Post 33, I saw the comment "Not been back" and thought it was the O.P, didn't notice you'd posted it. Thought that might have been obvious.
Click to expand...

What thelondonway was saying is that he hasn't been back to one of his clients that hasn't got lights. Not the best way to treat customers, one has to assume hes moonlighting
 
If the neutral for the lighting circuit is removed from the board and then indicates live then there are only 2 real reasons for this.Either there is a light switched on or there is some other device on the circuit using power,eg smoke alarm or burglar alarm,but it beats me why the op would be doing what he is doing!
 
Murdoch said:
What thelondonway was saying is that he hasn't been back to one of his clients that hasn't got lights. Not the best way to treat customers, one has to assume hes moonlighting
Click to expand...

excuse me the client is out of the country and isnt back until saturday 11pm ,
point your insults elsewhere
 
thelondonway said:
excuse me the client is out of the country and isnt back until saturday 11pm ,
point your insults elsewhere
Click to expand...

Matey, this is sooooooo basic its untrue.

Disconnect at cu and do simple dead tests using your MFT. YOU have done little or nothing to demonstrate you have done this or understand the reasoning for doing it so I'll give you the benefit of the doubt for ..........

As my signature bar says we are not mind readers and give as much information as possible - over to you.
 
phil d said:
If the neutral for the lighting circuit is removed from the board and then indicates live then there are only 2 real reasons for this.Either there is a light switched on or there is some other device on the circuit using power,eg smoke alarm or burglar alarm,but it beats me why the op would be doing what he is doing!
Click to expand...

He obviously doesn't want to live much longer.
 
Murdoch said:
Matey, this is sooooooo basic its untrue.

Disconnect at cu and do simple dead tests using your MFT. YOU have done little or nothing to demonstrate you have done this or understand the reasoning for doing it so I'll give you the benefit of the doubt for ..........

As my signature bar says we are not mind readers and give as much information as possible - over to you.
Click to expand...

matey get a grip n **** off
 

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