lighting circuit problem

[deroeper]

just rewiring a down stairs lighting circuit its all wall lights had faults all over the place on the existing wiring so decided to rewire all apart from kitchen lights .
it was all wired in 1mm so have changed it to 1.5mm all circuits are in jb's
and i have sitting room lights dining room lights landing light and kitchen now the kitchen is still in the 1mm wiring .
At each jb have done a IR test on each circuit before connecting all togeather all fine however when i connect the sitting room lights i get a reading of around 800mohms .
yet take it off feed all ok checked the mains feed and that is ok.
I am stumped could it be the old cable (1mm) thats giving me silly results (bearing in mind tested on own its fine) i am kinda chasing a ghost ! any idears.
using a Metrel tester .

 

[tony mc]

Is that 800 Meg ohms sounds good to me.

 

[i=p/u]

small m = mili

 

[MarkieSparkie]

Can you be more specific with the IR readings, 800mOhms? do you mean 800 Ohms or 800 MOhms? Where? L-N, L-E, N-E?

 

[tony mc]

Does this tester go up to 1000 M ohms on a test an if so when he tests the whole cct connected together is it now dropping down to 800 as you won't get milli ohms readins with a IR tester.

1/RT = 1/r1+1/r2 etc lower result when tested as whole

 

[tony mc]

Just had a look the Metrel 3100 IR tests go up to >1000 M ohms on IR testing so this might be the OP 's concern IMO.

 

[i=p/u]

dodgy question.. long as more than 1M ohm is compliant

 

[telectrix]

800Megohms could be achieved by breathing on the leads!!!!

 

[i=p/u]

explain telectrix

 

[telectrix]

moisture from breath across test leads.

 

[i=p/u]

was thinking moisture but hadnt a clue if you get me

 

[Martin Bradley]

Things you need to let us know, what tester are you using, what are the I/R test results before connecting living room lights, P/N P/E E/N for each, and after connection, also what are your continuity readings, any reason for leaving the 1mm kitchen lighting circuit, did you wire the drop downs to the wall lights, and switches.
if you think the cable to the living room light might be damaged, i would change that section. We await your response.

 

[deroeper]

Its a metrel easy test i am getting >1000 IR on all tests on individual junction box connections i.e living room, landing lights sitting room and kitchen now i connect them all to mains feed (which is also >1000) and i am in the clear except when i connect the dining room lights , which on there own gives me >1000 but connected the whole circuit drops to around the 800's . I havnt done the kitchen because of access problems , even though it is comming up >1000 . I cant find a leak anywhere its a neutral earth problem , and as i said everything is new apart from kitchen, would the old 1mm cable to the kitchen be giving me hassle when loaded with the rest of the circuit??
Oh and all wiring has been changed 1.5 down to wall lights as well.

 

[telectrix]

if you are getting 800meg. what are you worrying about. could be a tiny bit of leakage in a fitting. i certainly wouldn't lose any sleep over it.

 

[deroeper]

I suppose i like putting on my forms >1000 !! anally retentive!

 

[deroeper]

Things you need to let us know, what tester are you using, what are the I/R test results before connecting living room lights, P/N P/E E/N for each, and after connection, also what are your continuity readings, any reason for leaving the 1mm kitchen lighting circuit, did you wire the drop downs to the wall lights, and switches.
if you think the cable to the living room light might be damaged, i would change that section. We await your response.

Its a metrel easy test i am getting >1000 IR on all tests on individual junction box connections i.e living room, landing lights sitting room and kitchen now i connect them all to mains feed (which is also >1000) and i am in the clear except when i connect the dining room lights , which on there own gives me >1000 but connected the whole circuit drops to around the 800's . I havnt done the kitchen because of access problems , even though it is comming up >1000 . I cant find a leak anywhere its a neutral earth problem , and as i said everything is new apart from kitchen, would the old 1mm cable to the kitchen be giving me hassle when loaded with the rest of the circuit??
Oh and all wiring has been changed 1.5 down to wall lights as well

 

[telectrix]

mt MFT reads >99Mohms. that's good enough for me.

 

[Martin Bradley]

No problems with circuit, the reading is super.
Series and parallel

 

[deroeper]

I am a little confused (but i am blonde) > 1000 on my meter means there is no connection , its like holding the leads in the air , yes
surely if i have a reading in the 800's i have a leakage somewhere? dunno i have never put down on my sheets anything other than >1000 am i being dumb can someone explain??

 

[Martin Bradley]

Are you winding us up, have a look in your regs book what does it say about min value that is Acceptable, as this is exissting instalation
all values you have quoted are fine, even for a new installation.

you just need to be a bit more confident in your work.