continuity of final ring circuit conductors

[DirtyDog368]

Hello,

I am about to conduct my first initial verification and i have spent all weekend reviewing how to do the recommended tests. However I have a question regarding final ring circuit test.

1- is this only for a ring main circuit with outgoing line and incoming line?
2- if the answer is "yes" what happens if the ciruit is a spur from the distribution board?

cheers

DD368

 

[telectrix]

first, you measure the end to end on the RFC, r1,r2,rN. you would expect r1 and rN to be identical, and r2 to be 1.67 x r1 ( 2.5mm L/N, 1.5mm cpc.) then you x connect L and E at the CU and measure R1+R2. ( expect this to be (r1+r2)/4. this reading should be the same at every socket, except if you've got a spur, where the reading will be higher.

 

[malcolmsanford]

You will only do a ring final continuity tests on a ring final so that will be your tests for that.

If a spur is taken from the CU off of that RF then you will connect that the spur cable to say LINE 1 CPC 2 when you do the R1+R2 results and then take your reading around the ring as normal. If you so wish you could also again connect up when you do the LINE 2 CPC 1 side but thats being overly enthusiastic. After doing both sides you obviously note the highest value on your certificates.

 

[DirtyDog368]

ok i got you both but the Spur is coming from the cu directly, what tests should i do to ensure it is safe and installed correctly?

 

[malcolmsanford]

All the tests ie IR, continuity, polarity. R1+R2 etc

As I said in the post when you do the R1+R2 and cross connect the Line 1 to CPC 2 fit the spur LINE/CPC into the connector block with the other cables.

Same with the IR just croc clip all 3 Lines, 3 Neutrals and 3 CPCs

 

[Guest112]

does anyone do step 2?
After end to end resistance on L N CPC, cross connecting one outgoing line conductor to the returning neutral conductor and vice versa expected results (r1+rn)/4 and then doing step 3 cross connecting outgoing line returning cpc and vice versa expected results (r1+r2)/4.

 

[brucelee]

mate you have to do step 2 and 3 or you hvant completd the test correctly just carrying out end to end and using the calculated as your reading isnt correct and if there are spurs wont be accurate the
r1+rN/4 gives you the calculated for comparison with the measured at step 2 and then repeat for step 3 and record the highest line to cpc as your measured R1 +R2

 

[Guest112]

yeah i agree only mentioned it because all the previous posts skipped step 2 completely

 

[Risteard]

yeah i agree only mentioned it because all the previous posts skipped step 2 completely

Perhaps they should add an (R1+Rn) box to the schedule of test results for ring final circuits to ensure that the test is carried out.

 

[Guest112]

Perhaps they should add an (R1+Rn) box to the schedule of test results for ring final circuits to ensure that the test is carried out.

yes i suppose then atleast its recorded then

 

[Flying Ninja]

YES you MUST do both, If you don't you would not find a live earth reverse!!

 

[Risteard]

YES you MUST do both, If you don't you would not find a live earth reverse!!

I agree that you are required to conduct the test for a ring final circuit, but the dead polarity test, R1 + R2, won't detect a line/cpc reversal either. Inspection is more important than testing.

 

[Harry Worth]

I agree that you are required to conduct the test for a ring final circuit, but the dead polarity test, R1 + R2, won't detect a line/cpc reversal either. Inspection is more important than testing.

Isn't that why you do an R1+Rn as well on a ring final?

 

[Risteard]

Isn't that why you do an R1+Rn as well on a ring final?

Like I said it is required for testing continuity of ring final circuit conductors. The point I am making is that it is not a standard test for radial circuits so inspection is also important for polarity.

Tests are very much SECONDARY to inspection.