Understanding Test Results

[Shock Doctor]

Hi, Ive just altered a lighting circuit in a large victorian house and would just like someone to help me get a better understanding of my test results (I dont want to just be logging metre readings). My R1+R2 results were 11.3, my ZE was 0.22 but my ZS was 1.56. So if Ze + (R1+R2) = Zs my results dont add up. I realise that they are never bang on accurate but Im trying to see the connections and causes. Could it be old fittings that raised the R1+R2? Im just trying to learn so if it is something daft be gentle with me Ta!

Im off out now but I am very grateful for your time and advice.

 

[scotsparky]

sounds like parrallel earth paths

 

[SirKit Breaker]

You have read, or taken the reading the wrong, Ze = 0.22, Zs = 1.56. R1+R2 = Zs-Ze = 1.34 so your R1R2 reading should be about 1.34ohm. Null the leads and retest, if you are getting a Zs of 1.56 assuming 60898 mcb, then you are in spec by a long way, you know Ze is Ok so the problem lies with your R1R2 test method or dodgy leads.

if your Ze and Zs are in spec, which your post indicates that they are, and you have proved polarity whic a correct R1R2 test will prove, then dont worry about it, but try and find out where you have gone wrong.

Cheers.........Howard

 

[telectrix]

definitely incorrect measurement of R1+R2. your reading would indicate a circuit length of around 1000metres.

 

[pushrod]

As howard says - something up with that R1+R2 result - i would retest. Did it go up in stages when you were looking for the highest result. I would be tempted to use a wander lead to try and find where the problem is if you are still getting a dodgy reading. If you do still get a high reading i would say it must be on the cpc and you have a parallel path which is keeping the Zs low

 

[SirKit Breaker]

Got a question like this on my 2391.

 

[Shock Doctor]

Change of plan going out at 7.30! Thank you for your quick responses. Im back there tommorrow so I will retest the lot especially R1+R2 ( and check me leads!). Parrallel earth path could well be whats keeping my Zs low. At least I now Im not mental and am right to be investigating further. Telectrix it is a big house but your right its definitlet not a thousand metres for the upstairs lights! Everydays a school day!

Thank you again everyone for your time it is very appreciated.

 

[SirKit Breaker]

No probs mate. Dont be shy to click on the thanks and like buttons.

Cheers...Howard

 

[ezzzekiel]

sounds like a lost cpc possibly snapped in terminal somewhere, bit difficult to find if its a large house and you dont know how its wired, try dropping lights and checking cpc connected.

 

[Shock Doctor]

Hi all retested today all fine R1+R2 in region it should be. Put this one down to user error doh! Did allow myself to have a chuckle at what a numpty Id been.

Thanks again to all who contributed. Top people, Top site.