Continuity of CPC at Ceiling Rose

[KingKenny]

Had to leave a job early tonight, so couldn't resolve what should be a simple issue, but now it's buzzing round my brain. I have 5 ceiling rose's and pendants in a good old loop system. All 1 Way. I have good continuity readings at rose numbers 1,2,3 and 5. I have good continuity readings ALL the switches. All between 0.18 and 0.40 Ohms. BUT .... I'm getting an open circuit reading at Rose #4. I thought the issue might be poor earth connection at the rose, but this is fine - ditto the switch live and all the other cable connections at the rose appear to be tight in their blocks. So ... Given the switch appears to be fine and both the upstream rose (#3) and the downstream rose (#5) also appears to be fine, this leaves the cable from the switch to rose #4 as the likely issue does it not? Will the connection to the actual pendant, if loose cause this issue? - Thanks - KK

 

[telectrix]

if it's looped at the fittings, then either the cpc's have a poor connection at fitting, or it could be on the L from the switch, a high resistance in the switch. as the actual cpc is looped from fitting to fitting, the cpc to the switch should not have any effect on your reading. try a R2 reading on it's own to confirm.

 

[KingKenny]

Thanks tele - I'll do this. The cpc's certainly have a sound connection at the rose - it was the one thing I DID get a chance to do before I took one last reading at the rose.

 

[Octopus]

I'd disconnect the CPC's at rose #4 and reterminate in the fitting. Its worth trying.

 

[KingKenny]

I'd disconnect the CPC's at rose #4 and reterminate in the fitting. Its worth trying.

Yes, mate - That's was my first thought as to the issue - maybe a bit of sleeving caught in the earth terminal in the rose, so I stripped back the sleeving from all three cpc's (I'll replace them tomorrow and the installation is not live) and refixed them into the terminal at the rose. Still got an open circuit. No worries - I'll sort it out tomorrow.

 

[tony mc]

Are you testing with a wander lead !?

 

[GLENNSPARK]

if it's looped at the fittings, then either the cpc's have a poor connection at fitting, or it could be on the L from the switch, a high resistance in the switch. as the actual cpc is looped from fitting to fitting, the cpc to the switch should not have any effect on your reading. try a R2 reading on it's own to confirm.

best way tel.....
dont arse about with (R1 R2) when you`v lost it....straight to method 2....

 

[KingKenny]

I have a wander lead, but had no time to use it today.

 

[Octopus]

I have a wander lead, but had no time to use it today.

Probably quicker than R1 + R2 on a lighting circuit!

 

[KingKenny]

if it's looped at the fittings, then either the cpc's have a poor connection at fitting, or it could be on the L from the switch, a high resistance in the switch. as the actual cpc is looped from fitting to fitting, the cpc to the switch should not have any effect on your reading. try a R2 reading on it's own to confirm.

Thinking about this though. If the R1 + R2 reading at rose 3 is good, which it is, and the cpc from the switch to/for rose 4 doesn't effect the reading, then all that's left is the loop from rose 3 to rose 4. Interesting. R2 at both of these will prove this, yes?

 

[GLENNSPARK]

Probably quicker than R1 + R2 on a lighting circuit!

yeah it is....just a quick stab from point to point....

 

[GLENNSPARK]

Thinking about this though. If the R1 + R2 reading at rose 3 is good, which it is, and the cpc from the switch to/for rose 4 doesn't effect the reading, then all that's left is the loop from rose 3 to rose 4. Interesting. R2 at both of these will prove this, yes?

well....you know where your last point is where you got a value yes....
so anything beyond that where its open......
this is why method 2 is the choice here....you can just quickly go from point to point.....

 

[Outspoken]

Had to leave a job early tonight, so couldn't resolve what should be a simple issue, but now it's buzzing round my brain. I have 5 ceiling rose's and pendants in a good old loop system. All 1 Way. I have good continuity readings at rose numbers 1,2,3 and 5. I have good continuity readings ALL the switches. All between 0.18 and 0.40 Ohms. BUT .... I'm getting an open circuit reading at Rose #4. I thought the issue might be poor earth connection at the rose, but this is fine - ditto the switch live and all the other cable connections at the rose appear to be tight in their blocks. So ... Given the switch appears to be fine and both the upstream rose (#3) and the downstream rose (#5) also appears to be fine, this leaves the cable from the switch to rose #4 as the likely issue does it not? Will the connection to the actual pendant, if loose cause this issue? - Thanks - KK

So taking the chaff out of this we have the following;

• Conventional three plate lighting circuit in T&E with no two way switches at all
• Ceiling Rose #4 has an open circuit
• All legs of circuit appear to be OK except for the above mentioned fault.
• You have not yet tested the switch line from Rose#4 to switch#4

Questions;

1. Does the pendant/light actually work
2. Is this "open circuit" confined to the cpc (although I get this from your posts, as do the others, I would like you to confirm)
3. How are you actually testing the legs of the circuit to confirm their status?

Perhaps then you can get some more pointed advice.

 

[KingKenny]

So taking the chaff out of this we have the following;

• Conventional three plate lighting circuit in T&E with no two way switches at all
• Ceiling Rose #4 has an open circuit
• All legs of circuit appear to be OK except for the above mentioned fault.
• You have not yet tested the switch line from Rose#4 to switch#4

Questions;

1. Does the pendant/light actually work
2. Is this "open circuit" confined to the cpc (although I get this from your posts, as do the others, I would like you to confirm)
3. How are you actually testing the legs of the circuit to confirm their status?

Perhaps then you can get some more pointed advice.

Outspoken - Not quite. I have tested Continuity (R1 + R2) at the switch (ok) and the Light Pendant (Open Circuit). To answer your specific questions ... (1) Don't know (!) wanted to test before energising the circuit to see if the light works .... (2) Don't know - it was an assumption given I couldn't complete testing before I had to leave. R2 test tomorrow will confirm. (3) See the OP - I haven't had an opportunity to test fully as yet. Will (re) check connections at Rose 3 and Rose 4 tomorrow, then R2 test. Then I'll know more. I'll get the wander lead out and go from there.

 

[GLENNSPARK]

kenny....
go method 2.....forget (R1 R2)....1st prove R1....then go point to point on R2...
its the wander lead here mate.....