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- Dec 25, 2011
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I've been tidying up a ring circuit. 7 sockets run in 2.5mm T&E all in black and red. Various obvious issues to start with:
- Mixture of singles and twins - various makes and mix of metal and plastic face plates
- Back boxes loose, as in NOT screwed in, sat in massive holes in the wall, some packed with CARDBOARD
- No grommets
- No fly leads
- Wires short
- M3.5 threads stripped - some face plates on one screw only
- Wood screws in place of some of the M3.5s
I tested the circuit initially (calibrated Megger BM221 used) and end to end r2 was open circuit - one cpc was so SHORT in the back box it had not been connected to the faceplate. r1 and rn did NOT match anywhere near - probably as most L and N terminals were loose to some degree.
I have to date; replaced ALL the back boxes with doubles, properly set and screwed in. I've renewed 5No sockets to new 2G MK DP and kept 2No metal 2G metal ones. I have also extended a number of the short leads. This was done using a ratchet crimper with heat shrink butt crimps with another layer of heatshrink over the top as per the photos below:
Crimps:
Crimps insulated over:
Now going back and doing my end to end tests and I get:
r1 = 0.25ohms
rn = 0.25ohms
r2 = 0.61ohms
I was expecting something nearer 40ohms for r2 (as in cpc being x 1.67 the resistance). I suspect I have messed up on one or more of the cpc crimps somewhere. Does that look most likely?
Cross connecting the opposite ends of the ring (as per steps 2 & 3 in GN3) and then taking readings at each socket I get (all in ohms). Please note this was done direct to the terminals on the back on some and using a modded plug top "college special" on others. (I've just ordered a proper one.
L/N L/CPC
Skt 1 - 0.11 0.21
Skt 2 - 0.14 0.22
Skt 3 - 0.16 0.22
Skt 4 - 0.14 0.22
Skt 5 - 0.11 0.22
Skt 6 - 0.14 0.22
Skt 7 - 0.11 0.24
IR readings btw are all aok.
Is there an "easy way" of pinpointing which crimp could be at fault, do any of the L/N, L/CPC readings stand out?
I guess at the start I SHOULD have addressed the cpc continuity in that one socket and re-tested. Thanks in advance for looking at no doubt what is a newbie question!
- Mixture of singles and twins - various makes and mix of metal and plastic face plates
- Back boxes loose, as in NOT screwed in, sat in massive holes in the wall, some packed with CARDBOARD
- No grommets
- No fly leads
- Wires short
- M3.5 threads stripped - some face plates on one screw only
- Wood screws in place of some of the M3.5s
I tested the circuit initially (calibrated Megger BM221 used) and end to end r2 was open circuit - one cpc was so SHORT in the back box it had not been connected to the faceplate. r1 and rn did NOT match anywhere near - probably as most L and N terminals were loose to some degree.
I have to date; replaced ALL the back boxes with doubles, properly set and screwed in. I've renewed 5No sockets to new 2G MK DP and kept 2No metal 2G metal ones. I have also extended a number of the short leads. This was done using a ratchet crimper with heat shrink butt crimps with another layer of heatshrink over the top as per the photos below:
Crimps:
Crimps insulated over:
Now going back and doing my end to end tests and I get:
r1 = 0.25ohms
rn = 0.25ohms
r2 = 0.61ohms
I was expecting something nearer 40ohms for r2 (as in cpc being x 1.67 the resistance). I suspect I have messed up on one or more of the cpc crimps somewhere. Does that look most likely?
Cross connecting the opposite ends of the ring (as per steps 2 & 3 in GN3) and then taking readings at each socket I get (all in ohms). Please note this was done direct to the terminals on the back on some and using a modded plug top "college special" on others. (I've just ordered a proper one.
L/N L/CPC
Skt 1 - 0.11 0.21
Skt 2 - 0.14 0.22
Skt 3 - 0.16 0.22
Skt 4 - 0.14 0.22
Skt 5 - 0.11 0.22
Skt 6 - 0.14 0.22
Skt 7 - 0.11 0.24
IR readings btw are all aok.
Is there an "easy way" of pinpointing which crimp could be at fault, do any of the L/N, L/CPC readings stand out?
I guess at the start I SHOULD have addressed the cpc continuity in that one socket and re-tested. Thanks in advance for looking at no doubt what is a newbie question!
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