RFC CONTINUITY r1+r2

[nickblake]

Opps your right so sorry chaps ,brain in gear fingers not disregard my last post chaps im off to dunk my head in some water been a long day

 

[honest jon!]

end to end test of line, neutral and cpc give r1, rn, & r2 respectively.
r1+r2 = (R1+R2)
4

this is a good self-check and should match results from cross-connected results of R1+R2 from each socket outlet (excluding spurs etc which will be a higher reading R1+R2) to within 0.05 ohms.
It is also the best way of finding any spurs or inter-connects on the ring as they are not shown up with end-to-end r1, rn & r2 results.

 

[telectrix]

Opps your right so sorry chaps ,brain in gear fingers not disregard my last post chaps im off to dunk my head in some water been a long day

water, nick???? you ran out of beer then??

 

[nickblake]

After the rugby what do you think lol

 

[telectrix]

i blame that new stadium with it's plastic roof. should have been open and pouring down, as we all know, the welsh forwards walk on water.

 

[Smugley]

It's not untrue to say that resistance of a ring circuit when crossconnected and tested at various points will be greatest at the midpoint of the circuit.

For those reading this and trying to get their heads around resistances in parallel, the equation (r1+r2)/4 will give you 0.105 Ohms which is the expected resistance at the exact midpoint of the circuit. If you were to do the same test at the point of crossconnection, the resistance would be approximately 0.099. Not much of a detectable difference for the circuit length of 21.5m as described above, but perhaps more obvious over longer runs.
Yours Pedantically

 

[Sparky Ninja]

How does a figure 8 have a midpoint?

 

[Smugley]

Midpoint away from the crossconnection. In other words, the point where the two resistances being measured in parallel are equal. Assuming of course your conductors are of unequal size. If they are equal then the resistance will obviously be the same wherever it is tested.

(edit: Sorry, when I say crossconnection, I mean the point in the ring, at the consumer unit, where the incoming L is connected to the outgoing CPC and vice versa, and the midpoint is the position half way around the ring, where you would test resistance between L and CPC)

 

[Sparky Ninja]

Midpoint away from the crossconnection. In other words, the point where the two resistances being measured in parallel are equal. Assuming of course your conductors are of unequal size. If they are equal then the resistance will obviously be the same wherever it is tested.

(edit: Sorry, when I say crossconnection, I mean the point in the ring, at the consumer unit, where the incoming L is connected to the outgoing CPC and vice versa, and the midpoint is the position half way around the ring, where you would test resistance between L and CPC)

Oh ok, makes sense now thanks for clarifying.

 

[malcolmsanford]

After the rugby what do you think lol

i blame that new stadium with it's plastic roof. should have been open and pouring down, as we all know, the welsh forwards walk on water.

FULL-TIME: Wales 19 - England 26

Not sure what this as to do with testing a ring final circuit but in case anyone else is following this thread. I thought I had better put you in the picture.

Several illustrious members of our community on here seem to have been affected by the above score line. I can only hope that with counciling, full support of other members on here, and time they will be able to come to terms with what happened and perhaps pick up the pieces to carry on contributing to society ......................

 

[Golden_Boy]

Midpoint away from the crossconnection. In other words, the point where the two resistances being measured in parallel are equal. Assuming of course your conductors are of unequal size. If they are equal then the resistance will obviously be the same wherever it is tested.

(edit: Sorry, when I say crossconnection, I mean the point in the ring, at the consumer unit, where the incoming L is connected to the outgoing CPC and vice versa, and the midpoint is the position half way around the ring, where you would test resistance between L and CPC)

Thats why I like radials !!

 

[nickblake]

FULL-TIME: Wales 19 - England 26

Not sure what this as to do with testing a ring final circuit but in case anyone else is following this thread. I thought I had better put you in the picture.

Several illustrious members of our community on here seem to have been affected by the above score line. I can only hope that with counciling, full support of other members on here, and time they will be able to come to terms with what happened and perhaps pick up the pieces to carry on contributing to society ......................

i think it all came about after i made a complete plonker of my self by getting mixed up totally where the rugby bit came from im not sure

 

[telectrix]

it's because, if you can understand the offside rule in rugby union, then R1 +R2 should prove simple.

 

[nickblake]

thats where ive been going wrong , ill have to use my meter on the off side got it !! , cross legs test at every point reading should be the same if it increases then it could be a cross connection or a spur . see i did know just got totaly brain haked earlier in the thread

 

[keith915]

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????

GN3 Page 36