Resistance between Line and Neutral on a final ring circuit

[olsonn]

Hi

After a bit of advice:

I am just doing a bit of home testing prior to starting my 2391 later this month, but have come across a couple of strange results. Measured the R1 and got 0.98, also got the same for the Rn so not a bad start, but got 1.95 for the R2. I tested it a few times as I don't rate the Fluke crocodile clips, but got the same result. Cable is 2.5 so with 1.5 CPC expected 0.98 x 1.67 (1.63). I have checked for loose connections but all seems ok.? Then I joined the lines and neutrals (opposites) and measured at each socket. At the majority of sockets measured 48, which was fine 0.98+0.98/4 = 49. But on some double sockets one side measured 48, but other measured 97 or 98. Again I looked in the socket but no problems. Anybody any ideas? I know I could wait to my course starts, but really bugging me

 

[topquark]

Are you checking inside the socket with the accessory removed or using an R2 adapter. If you're using the adapter try inserting and removing it a few times on the side with the higher reading. If it doesn't reduce then replace the socket as it must be faulty, the wiring terminals for L/N are connected to both sockets. Even the newer higher integrity earthing sockets (with dual earth terminals) have the earths interconnected.

 

[malcolmsanford]

First if your just about to commence the 2391 then you need to start with terminology so your doing r1 rn and r2, I know it soundes perdantic but you need to start using it as your going to loose marks if you don't.

Your going to have to investigate to make sure you have a pure ring. The anomoly of the CPC can be a lot of things, how old is the installation, if it's over 30 yrs old it may have 1.0mm CPC or even a mixture. I know you say you have checked the sockets for loose or poor connections, but are there any JBs on the Ring, it is a high possibility if the installation is an old there could be a buried one somewhere. You may even have a cross over connection somewhere, this all adds to the fun.

The one about the R1 +R2 could that be a spur of the ring? It could also be if your using a socket and see type adaptor for taking the R1+R2 the socket outlets could be making a poor connection due to dust and age, it may even be cheap appliances as they often give you bogus readings.

All I can say is now welcome to the wonderful world of testing .................I doubt very much if you ever get, unless it's on an initial verication of a new install the expected results the theory tells us we should, this is why the 2392 is based on initial verication only and why the 2391-10 is harder as it will cover PIR work and older less co-operative installations.

 

[olsonn]

Hi

Yes I am using an adaptor, a Martindale. Your advice has worked a treat, you can't beat experience, just need to sort out the high CPC reading now

Thanks

 

[topquark]

I suspect the cpc is as malcolm has said, it's a 1.00mm cpc, try checking a known length of it.