RFC CONTINUITY r1+r2

[StokieSpark]

OK, please collect me if wrong.....

Measure end to end... line, cpc and neautral
add line and cpc resistance then divide by 4 ???

Record on test sheet????

 

[Amp David]

Don't forget to test again at your sockets with line and cpcs cross connected. Then take the highest reading, could be a spur.

Where would you like collecting from too? lol!

 

[StokieSpark]

collecting from?

 

[Sparky Ninja]

You're not wrong, however about 60% of the test is missing.

 

[StokieSpark]

So i cross connect line and cpc, measure at each s/o, record the highest reading i get?

 

[Sparky Ninja]

what about R1&RN?

 

[StokieSpark]

Yes to confirm polarity?

But i mean to record (r1+r2) on a sheet

 

[Sparky Ninja]

Yes to confirm polarity?

But i mean to record (r1+r2) on a sheet

(R1+R2).

What we record on sheets is irrelevant to what tests we carry out. We simply just take a selective amount of data for recording is all.

 

[StokieSpark]

Is the divide by 4 on the end to end tests and cross connection tests?

 

[Sintra]

If you are doing the tests correctly then there is no need to divide anything by 4.

 

[Sparky Ninja]

The divide by 4 is used to obtain a calculation used either at the design stage, or for comparison to measured values.

End to end line conductor (r1)
End to end cpc conductor (r2)
We add the two together, and divide by 4 as the parallel resistance in an R1&R2 both increases the cross sectional area and shortens the length.

So for example..

r1 = 0.16 ohms
r2 = 0.26 ohms

therefore... (R1&R2) = 0.16+0.26/4 = 0.10 ohms

This should be calculated for comparison only, and a measured value should be obtained and recorded. We have to measure at every point to verify polarity, identify any bridges and locate any spur legs where extra resistance will be present.

The figure of eight is connected and a reading taken at every point. Record the highest value as (R1&R2)

 

[SirKit Breaker]

1, Measure r1, rn, r2, and note the results.
2, Join the opposing legs r1 to rn both ends to make a figure of 8. Take R1+Rn at every outlet, should be a quarter of the r1+rn value.
3, join the opposing legs r1 to r2 both ends to make a figure of 8. Take R1+R2 at every outlet, should be a quarter of the r1+r2 value.

Spurs will be higher than any outlets on the ring. If you are testing 2.5T&E your R2 value will be 1.67 times the r1 or rn value. r1 and rn should be within 0.05ohm of each other.

The highest value found on the circuit is recorded as the R1+R2 value.

 

[StokieSpark]

Cheers widdler....

Bang on!

 

[nickblake]

Due to embarrasing cock up on this post ive deleted it due to the fact i had Zs im mind and Not R1 + R2

and the numpty award to night is presented to my self




Spot on widdler and sirkit beat me to it

 

[Sparky Ninja]

As the guys have said when you carry out the R1R2 test of the ring crossed legs L to CPC and test at each socket your readings will increase as you move round the ring and then decrease so the highest reading will identify the mid point of the ring ,and will identify any spurs the reading should be higher


Spot on widdler beat me to it

Just to clarify, I think you have the Zs expectant results confused there. The (R1&R2) should remain the same (if correctly cross connected) with spikes in the readings at spurs and drops at bridges where a parallel resistance may occur. The Zs test will raise towards the centre of the ring as the leakage current opts for the quickest return path when under test.