hi have a r1 r2 mystery

[ianphilip007]

hi have been doing some testing on a existing light circuit usual methos line /cpc linked at board leads and link lead nulled. come accross a very strange problem regurding a R1 R2 reading

Now measuring between sw live and cpc. rose 1/ 0.47 rose 2/1.15 (2WAY SWITCHING) 3 rose 3/0.51 rose 4/ 0.54 rose 5/1.07 rose6/1.97 (2 WAY SWITCHING)

all connections at rose 2 have been checked, switch connections on 2way switching checked, resistance of the actual switches has been measured and switches replaced as i just just thought it was a bad connection giving a false reading,or a high resistance switch but im still getting a high reading which is impossible as the R1 R2 reading at the next rose in the line is only 0.51. Its very strange as the measurment from loop in at the rose to CPC is fine and is as expectected which scuppered my other theory that this rose had been wired out of sequence.

any ideas any one. Just to add when ZS tested readings as expected which again just makes iot stranger.

 

[Octopus]

Had some similar this week (R1 + R2 of 2.4ish) whereas the "previous" fitting was 0.95, so I disconnected the pendent, fitted a new one and all the readings returned to what I was anticipating to see.

I was doing a CU change so couldn't see what the Zs would have been

Have fun.

 

[Sparky Ninja]

I would double check that it is not just resistance of the contacts in the switches.

 

[spark 68]

hi have been doing some testing on a existing light circuit usual methos line /cpc linked at board leads and link lead nulled. come accross a very strange problem regurding a R1 R2 reading

Now measuring between sw live and cpc. rose 1/ 0.47 rose 2/1.15 (2WAY SWITCHING) 3 rose 3/0.51 rose 4/ 0.54 rose 5/1.07 rose6/1.97 (2 WAY SWITCHING)

all connections at rose 2 have been checked, switch connections on 2way switching checked, resistance of the actual switches has been measured and switches replaced as i just just thought it was a bad connection giving a false reading,or a high resistance switch but im still getting a high reading which is impossible as the R1 R2 reading at the next rose in the line is only 0.51. Its very strange as the measurment from loop in at the rose to CPC is fine and is as expectected which scuppered my other theory that this rose had been wired out of sequence.

any ideas any one. Just to add when ZS tested readings as expected which again just makes iot stranger.

This could also be down to the different lengths of the switch drops, what are your readings like on the P Lives to CPC ?

 

[ianphilip007]

thats a thought one thing i didnt measure maybe its pendant giving a high reading at that point, what is baffling me is the next pendant is showing a lower reading surely this pendant would also be giving a high reading

 

[somersetsparks]

Could it not just be a long 2 way cable route? 1.15 isn't that high anyways

 

[ianphilip007]

readings on lopp lives to cpc are fine all away round the radial and as expected even at rose 2 (problem rose)

whats baffeling me is the high reading at rose 2 (R1 R2 ) between sl and cpc dissapears at the next rose. which seems impossible as all switches closed on circuit. if the reading is on rose 2 it should carry forward to rose 3 reading and so on

 

[ianphilip007]

the reading of 1.15 is not really a major problem its the fact the next rose is 0.51 which is impossible as the reading of the next rose has to be higher

 

[somersetsparks]

Not on 3 plate wiring though mate, the lives are looped at each fitting so you need to take a measurement at evry fitting really, regardless of which rose it is in the circuit, the landing light normally gives the highest reading due to its lengthy 2 way switch wires

 

[spark 68]

the reading of 1.15 is not really a major problem its the fact the next rose is 0.51 which is impossible as the reading of the next rose has to be higher

Why would it ?, as surely the next rose has it's own S/L, unless both on the same switch.

As I said it could be the longer switch drops, and as Widdler said it has to go through two switches on the 2-way circuit.

 

[Strima]

I'm with Widdler on this one, try bypassing the switch.

 

[ianphilip007]

the resistance measured at the rose (3) surely cant be lower than rose 2 no matter how long the switch wires are as the resistance measured at rose 3 should include this. if all switches on circuit are switched on

 

[spark 68]

the resistance measured at the rose (3) surely cant be lower than rose 2 no matter how long the switch wires are as the resistance measured at rose 3 should include this. if all switches on circuit are switched on

Yes it can,
think about it,
you have your PL to the rose which you said is fine, then it has to go through the length of the switch cable to the switch, and then through the switch and return back along the switch cable to the lamp connection, so depending on how long the switch cable is will alter your readings.

 

[ianphilip007]

yes totallly agree spark that the longer the switch run the higher the reading but wouldnt the previous switch run resistance still show if all the switches are in closed postion at the next rose or am i missing something simple here its been along day

 

[Strima]

yes totallly agree spark that the longer the switch run the higher the reading but wouldnt the previous switch run resistance still show if all the switches are in closed postion at the next rose or am i missing something simple here its been along day

No it wouldn't as your measuring the resistance on the loop and the specific switch run for that pendant. By your way of thinking non of the lights would work if the previous switch in the run was in the off position.