Pyro Cable Tripping RCD

[sl1210]

Went to a job in a church hall today where one of the power circuits was tripping the rcd. There seems to be 4 bad legs of pyro in the circuit, as I get a dead short in my IR tests between line/neutral, line/earth.

Is it common for pyro cable to do this after a certain time, or could a fault have caused this?

I have disconnected all the faulty legs and managed to keep the rcd on with only one socket working. I'm going to have to re-link the damaged pyro with new cable.

Was wandering if I could use 2.5mm FP cable clipped direct, or whether because its a church hall i would need to run it in plastic conduit???

Cheers

 

[sl1210]

o ohms

 

[telectrix]

try your tester on continuity. a reading of 0 meg. on a IR test could be several kohms. you need about 8 kohms or less to trip a 30mA RCD.

 

[MDJ]

i'm sure its damp too

Na can't see that, if the pot and seal were fitted properly and they obviously were due to the age of the circuit damp probably won't be the reason, you could stick a pyro under water and run over it with a steam roller and it will still work, also I very much doubt 4 legs are down, that seems almost impossible, unless alterations have been carried out by someone not familiar with MICC.

 

[Deleted member 26818]

Is it actually four legs though?
If you have a length of cable and damage one end, both ends would read as being damaged.
The OP appears to state that this is a single circuit supplying sockets.
It could be that the cable goes into the side of the first socket, then out the other side to th next socket.
Or it could be that the cable is run up at ceiling height and there are drops down to each socket.
One loop in and one loop out.
It may be that a pair of cables to a socket have been damaged, and the OP is reading it as four damaged legs, when in fact it's just two damaged cables.

 

[Knobhead]

Well having had a read through his previous started posts, I'll leave you gentlemen to it.

 

[hasel5]

nevera truer word spoken tony

 

[Golden_Boy]

o ohms

You cant have "0" ohms unless the short is exactly where you are measuring from.... I give up..

 

[GLENNSPARK]

why dont the O/P seperate each leg.....and test em individually rather than just goin round...n round...n round....
and stop using `extention leads` to test with...or any other crappy lashups like that....

 

[trev]

Was just about to suggest that Glenn, it's the only way. Work your way round the circuit leg by leg and you'll find your problem. You've probably gone round and round in circles and are now in the process of disappearing up your own backside, we've all been there and done it. As others have said, it's bar nigh impossible for 4 lengths of pyro to all go down at the same time.

 

[Deleted member 26818]

As others have said, it's bar nigh impossible for 4 lengths of pyro to all go down at the same time.

Reminds me of the Jubilee line extension.

 

[vjsmarwick]

i am still guessing that the problem has been caused by someone not knowing what they were doing and they have tried to tighten the pots a very big no no as we who know knows. and no i am not 50 yet lol but getting there faster every year!!!!!

Or another possibility is its a 4 core pyro and its just one length that is damaged and he is just not explaining it very well ????

 

[Guest55]

Reminds me of the Jubilee line extension.

why ? what happened there spin ?

 

[Guest55]

theres no shame in admitting you have no experience in pyro , its a dying skill that isnt taught anymore as its only used in a handful of building types.
i'm old enough to have been at college when it was still a practiced technique but its been over 6 years since i did any work on micc and i dont have , nor intend buying , the expensive tools to work with the stuff , and as such i avoid it like the plague.
i'll take fp200 any day as i know i can fix it in 2 minutes flat rather than fanny about for hours with blow torches and sealing putty.

 

[vjsmarwick]

well i would take pyro over fp200 any day and don't need expensive tools to make off the ends needs must when they are not available

 

[richy3333]

theres no shame in admitting you have no experience in pyro , its a dying skill that isnt taught anymore as its only used in a handful of building types.

Yeah but when you get some of the cantankerous posters on this forum combined with the fact that most sparkies are not overly eloquent with the typed word you can see why people are reticent to post or don't explain themselves as well as needed, and then you go around in circles trying to fathom out the fault/issue.

I still maintain prayer is you greatest weapon in resolving this problem...