How Did They Do That?

[inglishg]

Got called to an interesting faulty tonight...

Reported fault: Landing pir not working.

So, check end station aux power...ok

Check downstairs pir's...all ok

Check power in landing pir...NOT ok

Ah well...that must be a cut wire...so I traced it back to the panel. It was a relatively short run, and I had easy access to it. I found no damage.

After a bit of head scratching, I shorted the relay terminals in the pir and checked continuity back in the panel...NOT ok

What's going on 'ere then?

Anyway, I took the pir down, and in doing so, pulled on the individual cores. TWO just pulled through.

They were cut, and looking at the length of the cut wires, I assessed the cut must have been within the wall!

So, a straight rewire back to the panel, and all sorted...a happy customer

Afterwards, he told me that another "engineer" had spent all morning trying to sort it, and gave up saying "he would have to go and think about it, but be prepared to need a new system".

Tiz nice when a job comes together so well, and the customer paid me extremely well

[alterEGO]

Got called to an interesting faulty tonight...

Reported fault: Landing pir not working.

So, check end station aux power...ok

Check downstairs pir's...all ok

Check power in landing pir...NOT ok

Ah well...that must be a cut wire...so I traced it back to the panel. It was a relatively short run, and I had easy access to it. I found no damage.

After a bit of head scratching, I shorted the relay terminals in the pir and checked continuity back in the panel...NOT ok

What's going on 'ere then?

Anyway, I took the pir down, and in doing so, pulled on the individual cores. TWO just pulled through.

They were cut, and looking at the length of the cut wires, I assessed the cut must have been within the wall!

So, a straight rewire back to the panel, and all sorted...a happy customer

Afterwards, he told me that another "engineer" had spent all morning trying to sort it, and gave up saying "he would have to go and think about it, but be prepared to need a new system".

Tiz nice when a job comes together so well, and the customer paid me extremely well

whats hard about that? test cable out, soon as it dosn't bell out, replace it. sorted?

god help some guys on the hard ones.

[kka]

do you suspect skull duggery ?

[inglishg]

I don't think so - certainly not by the first engineer.

I started to look round for hidden cameras - that rogue traders programme perhaps.

I just don't have an explanation for why/how the the wire could be cut within the wall!

[lawandorder]

I don't think so - certainly not by the first engineer.

I started to look round for hidden cameras - that rogue traders programme perhaps.

I just don't have an explanation for why/how the the wire could be cut within the wall!

possibly chewed by rodent, quite common in cavities

[arfur mo]

possibly chewed by rodent, quite common in cavities

as above, perhaps as the pir's fixings were drilled, the tip has just caught the cable. could even be a 'stress fracture' if the installing engineer has given the cable a really ott yank because the cable got stuck pulling it in.

might even have been a damaged bit of cable at installation, and i've dealt with a couple of systems over the years with cable damage caused by carpet fitters where the carpets had been down on one for 4 - 5 years - go try explaining that to the client and telling them to try and reclaim the repair costs from the carpet co

for those who think this is a tall story, the fittere have very sharp thin bladed knives, so if they partially slice a cable the damage is like a paper cut and the plastic can actually pull the cable even if it partially severe's the cores together again enough to keep contact for the alarm to set. but copper eventually corrodes when atmosphere gets to it, so depending how damp the location, this affects how long the fault can take to appear.

often an occasional activation caused by this damage, this fault will be overlooked and put down to a pir or contact being faulty by the servicing engineer, especially if he has many calls to cover and not enough time for real thorough investigations, and it can be real tricky to spot for an inexperienced service engineer.

can i say a big well done to the o/p for sorting it properly, as many would simply have swapped over the cores

regs

alan

[Guest anguscanplay]

might even have been a damaged bit of cable at installation, and i've dealt with a couple of systems over the years with cable damage caused by carpet fitters

that a southern thing then - carpets as cavity wall insulation ? LOL

[satsuma01]

that a southern thing then - carpets as cavity wall insulation ? LOL

[Lectrician]

Never fully believe a customer either though! The PIR may have not worked since day one. They may have decorated, had cavity wall insulation, hung a picture, or any other type invasive works....

When you say cavity, are we talking a true brick/block cavity, or an internal stud wall?

[arfur mo]

that a southern thing then - carpets as cavity wall insulation ? LOL

we also use gripfill for underlay too

regs

alan