Neutrals!

[hoppy]

Hi

can someone please advise me as the best and easiest way to see if a house has borrowed neutrals, I have trawled previous posts but can't really find any clear answers.

All help is appreciated.

I have a couple of ideas but just want to see if I am thinking correctly.

My current college tutor says you can't test for a borrowed neutral.

Thanks

Craig

 

[needasparks]

Well Craig, I'm afraid your college tutor needs to go back to college, does he/she not know you can IR between circuits also.
Even taking a switch off tells you in most cases.

 

[Des 56]

Dont believe everything you hear in college,the tutors have their off days as well and are known to be wrong sometimes

 

[hoppy]

needasparks, when you say IR test between the 2 circuits do you mean testing live and neutral from say down lights joined together and test to live and neutral of up lights joined together, if you get a dead short then this indicated a borrowed neutral,

sorry if sound dumb just trying to get my head around this.

Thanks

Craig

 

[needasparks]

needasparks, when you say IR test between the 2 circuits do you mean testing live and neutral from say down lights joined together and test to live and neutral of up lights joined together, if you get a dead short then this indicated a borrowed neutral,

sorry if sound dumb just trying to get my head around this.

Thanks

Craig

It would not matter really, but if you take two separate circuits and IR between them they should have no conection.
Most common is up and down lighting, if you suspect a borrowed neutral just take a switch off in the hall and landing and you will see a cross link between switches or you could IR between lives and neutrals making sure you change switch position to see if lamp in line. This can also be found on wall lights where the live is taken from the lighting switch and neutral hopped of a socket. Again if you see wall lights in a property when testing it is worth testing between lighting and socket circuits. Its only a quick flash with the meter but can save a lot of agro fault finding later and narrows the check down. Thats why a full visual of a property is worth doing before any testing is made and gives you a heads up while your shoehorned under the stairs scraching your head.

 

[Geordie Spark]

Well Craig, I'm afraid your college tutor needs to go back to college, does he/she not know you can IR between circuits also.
Even taking a switch off tells you in most cases.

Those who can, DO.
Those who can't, TEACH !!!!

 

[adben]

hi,

I have no much experience here in Uk so correct me if I'm wrong. You could test if there are borrowed circuit neutrals wires using continuity test. From the panel, disconnect all circuit wires and test between circuit neautral lines. Infinity reading means no common neutrals between the circuit. make two test to make sure...first test is all light switch in off position and the second test in on position. The reason behind is some electricians accidentally connect the neutral to the light switch.

 

[needasparks]

You are correct in theory but you would only get a high resistive reading at best and may not pick up anything if cfl's or more resistive type lighting were in circuit. For the purposes of a Test we have to be 100% that circuits are separated entirely. A IR test will also be looking for fault between circuits also as we offen come across damaged cables. It is very important to understand your what you are testing and exactly what reading you are expecting to get.
Yes you can cross the road with one eye closed but would you ?

 

[Bogeybaiter]

Or there is the good ol rough as f**k method, turn 1 circuit on at a time and go splashing on the neutral bar

 

[telectrix]

most common is 2 way landing light. to test, switch off MCB for upstairs lights. then test in landing ceiling rose . if you read volts, then that L is from the downstairs circuit.

 

[oldtimer]

I mentioned that you do not see much of this in Scotland and in my 36 years I never seen it but the last 6 months I have seen 3. One was last week where I dont think it was meant to be a shared neutral me thinks that because they were wiring 2 light circuits ijn a 2 bed flat they have looped a neutral to the wrong light and when they powered it up no probs. Until muggins comes along anf fits a duel RCD board and yep that soon tells you you have a shared neutral.

 

[telectrix]

i think shared neutral is a better term than borrowed neutral. borrowed seems to imply that it's been taken away from 1 circuit to be returned at a later date, bit like a library book.

 

[SparkyDips]

most common is 2 way landing light. to test, switch off MCB for upstairs lights. then test in landing ceiling rose . if you read volts, then that L is from the downstairs circuit.

this is how i found it at a customers place.

i think shared neutral is a better term than borrowed neutral. borrowed seems to imply that it's been taken away from 1 circuit to be returned at a later date, bit like a library book.

lol and the penalty for not returning would be................. lol

 

[needasparks]

I mentioned that you do not see much of this in Scotland

Is that because they tend not to borrow and just steal a neutral as their tight

 

[Farmelectrics]

another quick way is to check switch in hall or landing should be a 3 core between switches if its 2 core youve got borrowed nuetrals