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I recently came across Pyro that had been sitting cut off in a damp basement. The last time made off Pyro was 3 years ago.
I have various cut offs and pots & glands with the intention of occasionally keeping in practice.


I had read all sorts of things from them in the past and seen various videos from them that look like they were made in the 70s.


Two things I remember from them that they said are myths:
(1) That moisture continues to get absorbed all the way through the cable. It only goes about 300mm and,
(2) Screwing on the pot until the inner shoulders are level. It should be through 3mm.


I have opened a few pots that have been outside for years. Even with a shroud moisture still gets in. The putty is sometimes green from the copper oxide.
They said that it still gets though the thread on the pot. I tried this out and it's true. I screwed a pot on to cable and put the lower part in water for 8 hours. A bead of water got though to the inside. That's why you should go through 3mm. It allows the putty to not just seal the thin edge, a dubious seal, but 3mm around the side as well.


Anyway, back to the first myth.
This Pyro is in a damp basement, and I mean damp. It gets flooded when raining and has a sump pump.
It must have been sitting cut off for over ten years.
An ideal opportunity to see if what they said holds up. I had to cut it away anyway so I decided to cut it 1 metre back, strip the cut bit to access the conductors and do an IR on it. As expected IR was about 0.05 Meg. I then started stripping the end that was exposed. As I did the IR started going up until I got to >999 at about 300mm.
So there you go. It's true.


However:
There are two strange things that have happened. Pyro is supposed to be "everlasting", and maybe it will last a lifetime in most cases but I tried this on another 5 metre piece of Pyro, that was inside a warm environment, that was around 25 years old.
I cut from both ends, making sure that the conductors were away from the sheath after the cut, and although the IR went down a bit, it still stayed at around 25 Meg. Just in case there was damage that was so small I could not see it I cut it in half and done the same to both halves. I then tried this with some more old Pyro from a different building on the same site and another site and as soon as I cut off the ends the IR went right up to >999.
I have not done this experiment before (nor do I intend to do it again) so I don't know how many lengths of Pyro behave like this but it seems strange that with the fact that moisture does not get absorbed more that 300mm it has managed to infiltrate this particular Pyro all the way along the length to give it an IR of 25 instead of >999.


Anyway, you may be wondering about the "Super Magic" bit in the title.
There is one bit of Pyro that behaved in a strange way. Before I came across the one sitting in the damp basement I had taken a small length of Pyro home to see how deep the moisture penetration would go after a day/week/month.
Now I had heard that the magnesium oxide had been improved to resist moisture (although I don't know if that's really true) but this bit surprised me.
I cut it off one end, stripped and sealed to have the conductors to test from, then cut 400mm the other end.
Tested >999
Left 1 hour >999
12 hours >999
1 day >999
Strange. Put the end on the spout of a boiling kettle.
Tested 0.50
1/2 hour >999 .... WHAT!
Dipped it in water for ten mins.
Tested 0.00
1 min same.
1/2 hour about 400
1 hour >999.


DA DAA! SUPER MAGIC PYRO.


And yes, I did check the batteries in the tester. MFT1710.




Any thoughts on these 2 strange anomalies?
 
Enjoy the experimenting.
I wouldn't call it magic but it is top notch stuff.
When it comes to certain situations MICC is in a class of it's own and was way ahead of it's time. What happens......we put it on the backburner because of cost and go for cheaper to produce, cheaper to install, inadequate, sub standard shyte.
 
An interesting write up that would have benefited from identifying the manufacturer of each piece of MICC tested and termination accessories used which may or may not have some bearing on the differing results achieved. It was quite common when MI was used almost daily to find one manufacturers cable terminated with another manufacturers accessories which could contribute to some of your findings with moisture ingress into seals / pots

I remember my curiosity some 25 - 30 years ago with all the moisture creep claims and experimented with Pyrotenax, AEI mineral and Wrexham mineral who were the three manufacturers at the time, one of the new boys on the block (AEI I think) to slowdown or prevent moisture creep added silicone to the insulation material, I had three part coils (1 from each manufacturer) 5 - 10 metres long one end was terminated and the other put in a bucket of water after initial testing over many months they were tested and from what I remember there was little to choose between them and chopping off 6 - 8in and then stripping them to terminate got rid of most of the moisture
Most the seals I have seen where problems have occurred have been the result of poor filling with air pockets left in the compound which will allow moisture in and there is also the possibility of condensation

Even with these very minor problems it is still a superior cable that requires a lot of skill and understanding to install properly it's a pity it is now so expensive it cannot compete with the other "fire rated" cables that have tried to steal it's crown
 
I thought there was something done at some time to improve the prevention of moisture ingress but it was just a vague recollection in my mind about something I had heard years ago.
You have confirmed that it was true. I didn't know how it was done so thanks for the information about the added silicon.
However, your experiment seems to suggest that this made no difference although if you chopped of 6 - 8in all at once on each one you would not have known how far the moisture penetrated. When I did it I chopped off 10mm at a time and tested each time. So the silicon one may have won out after all.
Maybe that is it. The one that is rejecting moisture may well be the one with silicon added.
I was just very surprised that it did that, it was so unexpected.

On a side note, everyone seems to slag off the MI replacements like FP, Firetech, Firetuff etc.
You cannot compare the two types. These cables have their place and are ideal replacements for MI in a lot of installations. MI still has its place as well. You could never use FP in ships and certain industrial installations, but like you say, it's a pity it's now so expensive. I have been working with an "improver" and he says that MI is not taught in collage or included an the AM2 anymore. It's now being considered specialized. The last time I made one off was 3 years ago. All my Pyro tools are feeling neglected. Anyway, I'm now rambling so....
 
I recently came across Pyro that had been sitting cut off in a damp basement. The last time made off Pyro was 3 years ago.
I have various cut offs and pots & glands with the intention of occasionally keeping in practice.


I had read all sorts of things from them in the past and seen various videos from them that look like they were made in the 70s.


Two things I remember from them that they said are myths:
(1) That moisture continues to get absorbed all the way through the cable. It only goes about 300mm and,
(2) Screwing on the pot until the inner shoulders are level. It should be through 3mm.


I have opened a few pots that have been outside for years. Even with a shroud moisture still gets in. The putty is sometimes green from the copper oxide.
They said that it still gets though the thread on the pot. I tried this out and it's true. I screwed a pot on to cable and put the lower part in water for 8 hours. A bead of water got though to the inside. That's why you should go through 3mm. It allows the putty to not just seal the thin edge, a dubious seal, but 3mm around the side as well.


Anyway, back to the first myth.
This Pyro is in a damp basement, and I mean damp. It gets flooded when raining and has a sump pump.
It must have been sitting cut off for over ten years.
An ideal opportunity to see if what they said holds up. I had to cut it away anyway so I decided to cut it 1 metre back, strip the cut bit to access the conductors and do an IR on it. As expected IR was about 0.05 Meg. I then started stripping the end that was exposed. As I did the IR started going up until I got to >999 at about 300mm.
So there you go. It's true.


However:
There are two strange things that have happened. Pyro is supposed to be "everlasting", and maybe it will last a lifetime in most cases but I tried this on another 5 metre piece of Pyro, that was inside a warm environment, that was around 25 years old.
I cut from both ends, making sure that the conductors were away from the sheath after the cut, and although the IR went down a bit, it still stayed at around 25 Meg. Just in case there was damage that was so small I could not see it I cut it in half and done the same to both halves. I then tried this with some more old Pyro from a different building on the same site and another site and as soon as I cut off the ends the IR went right up to >999.
I have not done this experiment before (nor do I intend to do it again) so I don't know how many lengths of Pyro behave like this but it seems strange that with the fact that moisture does not get absorbed more that 300mm it has managed to infiltrate this particular Pyro all the way along the length to give it an IR of 25 instead of >999.


Anyway, you may be wondering about the "Super Magic" bit in the title.
There is one bit of Pyro that behaved in a strange way. Before I came across the one sitting in the damp basement I had taken a small length of Pyro home to see how deep the moisture penetration would go after a day/week/month.
Now I had heard that the magnesium oxide had been improved to resist moisture (although I don't know if that's really true) but this bit surprised me.
I cut it off one end, stripped and sealed to have the conductors to test from, then cut 400mm the other end.
Tested >999
Left 1 hour >999
12 hours >999
1 day >999
Strange. Put the end on the spout of a boiling kettle.
Tested 0.50
1/2 hour >999 .... WHAT!
Dipped it in water for ten mins.
Tested 0.00
1 min same.
1/2 hour about 400
1 hour >999.


DA DAA! SUPER MAGIC PYRO.


And yes, I did check the batteries in the tester. MFT1710.




Any thoughts on these 2 strange anomalies?


I have been out of the lop as far as MICC is concerned, and your post interested me, as my very first introduction to this trade was wit MICC.

I would like to ask what kind of termination / gland/ seal types you are basing your theory's on? as there are many types of gland assemblies for differing types of installations.

Not trying to debunk your theory's it's a relevant question, hope you can clarify.
 
I
I have opened a few pots that have been outside for years. Even with a shroud moisture still gets in. The putty is sometimes green from the copper oxide.
They said that it still gets though the thread on the pot. I tried this out and it's true. I screwed a pot on to cable and put the lower part in water for 8 hours. A bead of water got though to the inside. That's why you should go through 3mm. It allows the putty to not just seal the thin edge, a dubious seal, but 3mm around the side as well.

Are you sure it's not just that they had been sealed with the green compound which used to be common before the White/grey modern stuff was used?

Why would you want the pot to be resistant to immersion in water? The compression ring of the gland is there to prevent serious water ingress, the pot it there to contain the compound which seals the end of the cable against absorbing moisture from humidity.




Sent from my iPad using Tapatalk
 
Pete999

I am not using any glands/pots etc. This is just an experiment with some MI with regard to the way it absorbs moisture etc. It's just that I was surprised when the mag ox actually dried out after being put in direct contact with both steam and water. 2 other pieces of MI from different locations did not do that. After only 30 mins the IR went down quite a lot. This one done the opposite.

davesparks

I think you are right. I wrongly assumed that due to the age and the fact that it was unshrouded outside it may have been moisture ingress turning the inside green with copper oxide, a bit like the plasticisers greeny oil from older PVC due to the copper. I now remember coming across a very old tin of pot sealer that was dark green. I think it was from the 60s. I've only ever experienced it being gray from collage days in the early 90s.
Mind you, I have recently come across a seal that used a hard plastic seal with a very hard rubber like green sealant on the Pyro end. No one has seen anything like it before. I should have taken pics of it. Some were with, and some without earth tails. An IR test showed the same as one of that age with pots.

I don't want the pot to be resistant to immersion in water. What I did was just an experiment to see if the pot sealed on the Pyro as I didn't think it did; you would have a lot of trouble getting it on if it were that tight. The litrature (from BICC I think) specifically said that it would not seal against long term moisture ingress, nor would the gland. The only way to get a moisture resistant seal was to ensure the putty sealed all the way around the end of the Pyro and the best way to do that was to have about 3mm through so it seals around the side and not just the end where there is only a thin surface to seal to. I was taught in collage to screw it on up to the inner shoulder and all the sparks I've worked with have done the same, but about six months ago I found out that was wrong.

Like I say, only experimenting on scrap while I had the chance and inclination.
 
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