Pyro Cabling?

Snapester · Mar 29, 2012

Hi guys, i did some work on a flat just over a year ago and tested and did a PIR which i passed as good condition after the remedial work!
Tenants in the flat having issue with cooker circuit in which the property maintenance guy came to have a look at, to which he said needs a full rewire and pyro should not be used anymore! Go figure do any other sparky folk feel this way? I believe Pyro is one of the most bullet proof installations available?
Cheers

mackers · Mar 31, 2012

ackbarthestar said:
Interesting, I was once shown how to IR test the MI one end at a time because if it goes down at one end after you have made off the other you will have a 50% chance of choosing the right (wrong) end to take apart.

To be more explicit, sometimes when cutting the thread with the pot/wrench a very small slither of copper, unseen by the eye can get caught and when filled and crimped the copper slither shorts across the conductors. I know it happened to me once when putting in a fire alarm system in a school and needed help to find the fault. The faulted end was subsequently burned out with a IR test set at 1000V

When installed properly it will last for years, the problem comes when other sparks mess around with it once in place.

yep one end at a time when i was a lad we sat in lock up making ends off on all the coils of pyro /micc then when cable was needed one end was already made off for the spark also good practice for us,big trouble if any burs where left in pot! LOL

trev · Mar 31, 2012

GLENNSPARK said:
"its outdated and you should be using fp200"......surely this lecturer should see that you use the most appropriate cable/s for the installation/environment...including pyro......so what he was saying was a load of crap.......

The same guy would probably say in every circumstance that you WILL use 2.5 for socket outlets.
Knob

GLENNSPARK · Apr 1, 2012

trev said:
The same guy would probably say in every circumstance that you WILL use 2.5 for socket outlets.
Knob

the thing is here n all Trev...is lecturers and those who take up jobs passing knowledge on shouldn`t be negating to teach the pro`s n cons of different cable/s and systems on the basis that `its old hat`...or some other nonsense like that....i mean...how are folk supposed to learn with dismissive attitudes like this.....

GLENNSPARK · Apr 1, 2012

trev said:
The same guy would probably say in every circumstance that you WILL use 2.5 for socket outlets.
Knob

and further to this n all trev....is the fact that to get over the issues of derating for insulation....you may find yourself using 4.0mm......a lot of newbuilds have insulation under floors and in ceiling voids now.....

UNG · Apr 1, 2012

ackbarthestar said:
When installed properly it will last for years, the problem comes when other sparks mess around with it once in place.

You would have to enlighten me as to what the problem is "when other sparks mess around with it once in place" I have altered many Pyro installations that were installed many years before with no problems whatsoever. In fact the only problem if it is a problem is more skill and understanding of the cable is needed to modify an installation that has been in place for a number of years

ackbarthestar · Apr 1, 2012

I would agree, there is not enough training and consequently not enough experience when dealing with this cable system. So somebody without the necessary experience is likely to degrade the cable through poor connections.

Snapester · Apr 6, 2012

Hi guys, went back to this job today to have a look at the issue, and apparently it was sparking at the cooker switch but no signs of blackening etc so dubious about that! Although the customer had ripped down a wall cabinet exposing the original outlet which had been chock blocked and the fitting looked a little rusty, it was spidered off from here!!
I Tested the Continuity of CPC - Line was good 0.09 and Line-Line 0.06, the insulation test was however at 32.3Mohms so not great but for the age i would say its good.
After poking about the 4mm PYRO is supplying 2x Socket Outlets, Cooker Hood, 7Kw Hob & Cooker on 13amp plug and also washing machine!! Possible overload as this is on a 32a breaker although it had not tripped!
Now looking in my greenbook of answers it shows me that 4mm PYRO Bare & Not exposed to touch nor i contact with combustable material but it only shows clipped direct or on tray? This is in a Concrete wall?? What is the CCC of it would it be around 40a? as the load i would estimate is around 45amps if it was fully loaded!!

Cheers

ackbarthestar · Apr 6, 2012

I think MI cable is rated at 55A clipped direct and 60A on tray, heavy duty and 51A and 54A for light duty (App4. table 4G2A)

Its more likely to be those woosy washing machines causing some form of capacitive discharge !

Snapester · Apr 6, 2012

Yeah i see it as 51A clipped or 54A on a tray? No word of in a wall? I have told the customer that it would be better to install a small circuit to take the kitchen sockets and washing machine and leave the MI for the cooker and hob?
Although i don't believe the circuit to be overloaded if the 32A MCB has not even tripped out and its unlikely the MI would have become overloaded, i think more bad connections in the awful joint hidden behind the wall unit?