SY cable to replace MICC

[Engineer54]

ENG 54. I've definitely had it happen with the pyro. swelling and proved it by using a micrometer,
When at college they took us to the pyro factory local to us and one of the things they told us there was the dampness never travels down the cable any more than about 6in. No matter how long it was exposed to damp, so we were always told to size the about a foot in. (if size was unknown). This was the old imperial micc. I do believe they actually treated the manganese in later cable to stop dampness travelling.

The point I was trying to make was if damp had gotten into the cable then the end may have needed to be stripped back a bit more, thus making the cable a bit short.

As i say, i've never come across this. maybe you're right if we're talking about the light duty stuff, but to be honest, i can't ever remembering using it. I can't really see the thicker walled MICC cable sheaths being expanded by damp in the magnesium, copper may be soft but not that soft. Come across plenty of pot's that have been slightly undersized and been a real bugger to get threaded on to cable though!! lol!!

Always used to chop the first foot or so off a new coil before use, whether it had been sealed or not, ...just became a habit!! lol!!

 

[Guest55]

What cable another contractor uses is he look out, but as in taking responsibility for the installation I have to be confident in its safety. Are you telling be you'd be happy signing the completion certificate, saying the installation conforms with regs when this was left in circuit?

why do you need to complete a certificate that covers another contractors work ?

 

[UNG]

ENG 54. I've definitely had it happen with the pyro. swelling and proved it by using a micrometer,
When at college they took us to the pyro factory local to us and one of the things they told us there was the dampness never travels down the cable any more than about 6in. No matter how long it was exposed to damp, so we were always told to size the about a foot in. (if size was unknown). This was the old imperial micc. I do believe they actually treated the manganese in later cable to stop dampness travelling.

The point I was trying to make was if damp had gotten into the cable then the end may have needed to be stripped back a bit more, thus making the cable a bit short.

You must be the only one that has seen Pyro swell with damp this is a new one on me not seen any slight hint of this in the 30+ years I've been installing Pyro and repairing Pyro faults

The method by which Pyro is made would account for the slight variations in sheath diameter and the accepted manufacturing tolerances probably account for this with other companies using different manufacturing methods including seam welding the sheath this could also affect sheath diameter depending on which axis of the sheath the measurement was taken, the fact that to measure this swell needed a micrometer makes me think this is a case of mountains and molehills as the increase in diameter was marginal and of no consequence

Some people are to quick to jump to conclusions with Pyro through a lack of understanding and knowledge of how to work it

 

[itselectric]

You must be the only one that has seen Pyro swell with damp this is a new one on me not seen any slight hint of this in the 30+ years I've been installing Pyro and repairing Pyro faults

The method by which Pyro is made would account for the slight variations in sheath diameter and the accepted manufacturing tolerances probably account for this with other companies using different manufacturing methods including seam welding the sheath this could also affect sheath diameter depending on which axis of the sheath the measurement was taken, the fact that to measure this swell needed a micrometer makes me think this is a case of mountains and molehills as the increase in diameter was marginal and of no consequence

Some people are to quick to jump to conclusions with Pyro through a lack of understanding and knowledge of how to work it

I can go back to mid 60's and I can assure you it has happened to me and others at the time.
As I said in my previous post I think the manganese was treated to stop dampness migrating as far
And as eng 54 said it was on the smaller cables.

 

[Dcf]

maybe a bit of fp would have been a better choice of cable...or dare i say it a bit of micc!
on another thread i bemoaned the use of yy in shopfit situations. sy without the braid
as i stated these are control cables for use in automation etc not fixed wiring cables in my book
i bet you the sy braid wasnt even earthed

 

[Engineer54]

maybe a bit of fp would have been a better choice of cable...or dare i say it a bit of micc!
on another thread i bemoaned the use of yy in shopfit situations. sy without the braid
as i stated these are control cables for use in automation etc not fixed wiring cables in my book
i bet you the sy braid wasnt even earthed

Not on a listed building that has been wired throughout in MICC!! Pretty sure the insurance company that is covering this building, wouldn't be too pleased with any substitute cable type being used.

 

[vxwestie]

why do you need to complete a certificate that covers another contractors work ?

Because I am carrying out major alterations, consumer unit changes, earthing etc etc. and as I'm sure you will be aware, a completion cert contains a section on the condition of the existing installation.....
Ive been asked to carry out improvements to ensure the installation meets bs7671. I cannot complete that whilst leaving unsuitable cable installed...

 

[vxwestie]

I've been thinking of this subject now for a week or more. The reason I posted it on this site looking for advice and back-up was to get other peoples opinions on how to act on the matter.
I can't quite believe that I've been asked as to what difference it makes to me what another contractor has done? Or suggested that I'm causing trouble.
The fact of the matter is that as I'm carrying out the works and look after the property, I am responsible for its safety and condition. My clients (actually a group of trustees) aren't going to have the first idea whether what another contractor has done, is right or not, without me guiding them. If I do not question the work or requirements, I am as bad as the person who installed it.
I'm sure with my signature on the completion certificate and name on the clients cheque book stub, no insurance company or legal eagle in the county would have difficulty in pinning responsibility upon me if there was a problem...

 

[Darkwood]

You created another thread previous to this one i believe i gave you the answers you seek as to why its not a suitable cable ... im a little confused why you started another almost identical thread ... scanning through it the answers given seem to be the same..:thinking: