ring testing

[soulman]

i have been practicing testing before i return to college in september, i have moved from my test rig onto my own house. i was testing the downstairs ring. the problem i have is when testing at the socket outlets line & neutral cross connected. i should have had around 0.30 at each outlet, out of 12 sockets only half were this figure some were around 0.45 and some as high as 0.76. i double checked all connections were tight, all sockets are metal. Any ideas as i was expecting roughly the same at each outlet. Also there are no spurs. cheers for any help a little confused!

 

[philip962]

From what I remember they can be different as long as they are no more than 1.87 i am no testing guru but I think this is right if not I will be shot down in flames within mins on here gn3 should be able to clear it up

 

[pevvers]

From what I remember they can be different as long as they are no more than 1.87 i am no testing guru but I think this is right if not I will be shot down in flames within mins on here gn3 should be able to clear it up

Unfortunately you are incorrect, the 1.67 value you are thinking of is to calculate what the approximate value of the end to end resistance of the CPC should be, i.e. multiply the line end to end value by 1.67.

It sounds like a dodgy ring to me, or maybe shoddy sockets not making good contact. Sometimes different sides of double sockets give different readings on the low 200mA test current applied on a continuity test.

Personally, I would do the line to CPC test and see whether this gives the same magnitude of variation across the circuit at the same points.

 

[soulman]

i will try that tommorrow. it is a new build property so i would have thought that ring would be ok

 

[keniff]

some of them may be spurs? what is your end to end resistances on r1 r2 rn? try adding your end to end resistances together RN and R1 does this give you measurments a bit closer to what you are expecting?

 

[pevvers]

i will try that tommorrow. it is a new build property so i would have thought that ring would be ok

What I learnt a long time ago in this game is to trust nobody!

New builds can be just as bad as existing installations, especially if it is domestic... You don't know what's gone on in the installation, and there could be a bodge in there somewhere. As said, the line to CPC reading will show you whether it is the same across all parts of the circuit using another conductor.

 

[RETIREDSPARKY]

The 1.67 only refers to the ratio of 2.5mm2 line/neutral and 1.5mm2 cpc ie 2.5/1.5=1.67. Therfore if your ring has a different cpc csa ie smaller than line or neutral ie 4/2.5 the the ratio would be 1.6 and so on.

 

[Plonker 3]

Are you sure you have crossed the line and neutral cables correctly, these results sound like you havent if that is the case.

What were your readings for Rn & R1 continuity?

 

[soulman]

thanks for replies definately not spurs and definately cross connected correctly. i have spoken to a spark tonight and he said pick one of the sockets with high readings and change it to a plastic one and retest. he is convinced it is the metalic sockets. i never thought to ask him could it be because im testing at a socket outlet rather than the board with the neutral connected to the neutral bar.

 

[Golden_Boy]

Are you sure you have crossed the line and neutral cables correctly, these results sound like you havent if that is the case.

What were your readings for Rn & R1 continuity?

I would suggest doing the checks from the rear of the sockets, directly on the conductors , this should remove any issues caused by switches and poor conections at the plug adaptor ( I am assuming you are nseing on of these ?)

 

[JUD]

I would also check that none of the terminal screws have been tightened down on the conductor insulation

 

[thebassman]

Hi There

I had similar problem during our annual accessment whie checking a ring the socket i picked had a reading that the inspector said must be a spur, this was a complete rewire to prove my point i removed every socket, it turned out the problem was the twin socket we picked to take reading left hand side was ok right hand side was higher changed socket over and all was well, so as suggested in another test from back of socket a bit more hassle but stops sockets causing problems

Danny

 

[Golden_Boy]

Hi There

I had similar problem during our annual accessment whie checking a ring the socket i picked had a reading that the inspector said must be a spur, this was a complete rewire to prove my point i removed every socket, it turned out the problem was the twin socket we picked to take reading left hand side was ok right hand side was higher changed socket over and all was well, so as suggested in another test from back of socket a bit more hassle but stops sockets causing problems

Danny

Is there an Echo in here?

 

[pevvers]

Is there an Echo in here?

I reckon so, I said about different readings each side of the socket yesterday...

 

[soulman]

hi just to update you performed the tests today on the upstairs ring and got crazy results. so i removed sockets as advised and got perfect results, testing the actual terminals on the rear of the sockets. the sockets were mixed upstairs plastic & metal and i still got strange readings on plastic. So i,ve ruled out socket type. could it be my tester which is new, fluke 1652b i was using the socket cable that came with the machine. so i have now ordered a r2 socket interface adapter to see if that makes any difference. is this common on socket circuits. please note i'm cross connecting at a socket rather than the cu, if that makes any difference

cheers