Pyro Cable

[R1CH-G]

Just a bit of history first. The following occurred in what is classed as a bunker in the military sense of the word, and all works were carried out to JSP military regs.

Cable used was 2H10 orange sheathed pyro (low smoke zero halides). Cables was potted and glanded and insulation resistance readings taken (500 volts on Fluke 1652) and came back at >500 MegOhms. This cable sat there happily for over 4 months until I got a call saying the DB had gone bang!!

On inspection, the pot was blown to bits! The only thing I can put this down to was dodgy compound and tracking.

Anyone out there who could suggest any alternatives, because for the life of me, I can't work this one out!

 

[i=p/u]

probably ied

 

[R1CH-G]

probably ied

Not understandy...

 

[i=p/u]

im joking, you probably correct. no expierience

 

[sparky3366]

usually a good idea to use potting conpound instead of semtex...

 

[R1CH-G]

usually a good idea to use potting conpound instead of semtex...

Ah, note to self - don't use semtex

 

[Engineer54]

You wouldn't be the first to experience, what you call ''Dodgy Compound'' lol!!! Can also be old compound that's been on the shelve, past it's sell-by date. The only other thing i can think of in your case is moisture, but i would imagine the length you stripped back for a CU connection, the >500 meg and 4 months in service would justifiably nullify that possibility. ...lol!!!

 

[R1CH-G]

You wouldn't be the first to experience, what you call ''Dodgy Compound'' lol!!! Can also be old compound that's been on the shelve, past it's sell-by date. The only other thing i can think of in your case is moisture, but i would imagine the length you stripped back for a CU connection, the >500 meg and 4 months in service would justifiably nullify that possibility. ...lol!!!

Like I said, it's got me baffled. Only thing I could think of was dodgy compound. I wouldn't imagine that 2H10 pyro exactly flies off the shelves!

 

[DurhamSparky]

JSP military regs

hmmmm yeah i worked to them.. i suggest a rewire based on that fact alone!! lol...!

 

[R1CH-G]

JSP military regs

hmmmm yeah i worked to them.. i suggest a rewire based on that fact alone!! lol...!

You probably wouldn't be far wrong either!! JSP - BECAUSE WE SAY SO OK?????

 

[DurhamSparky]

yup!! JSP Testing of Circuits = BANG TEST!

loads of concessions and deviations as required lol...!

 

[johnboy6083]

could it be air in the pot, sealed in by compound, and then charged by the conductors?

 

[millwall ken]

You probably wouldn't be far wrong either!! JSP - BECAUSE WE SAY SO OK?????

Joint Services Personnel Military Regs?????????

 

[olly w]

Joint Services Personnel Military Regs?????????

Joint Services Publications. JSP 375 Vol 3 Chapter 3 Electrical...

But as far as I remember they always stated IAW BS7671 so how the cable was installed badly I don't know?

 

[R1CH-G]

Joint Services Publications. JSP 375 Vol 3 Chapter 3 Electrical...

But as far as I remember they always stated IAW BS7671 so how the cable was installed badly I don't know?

The cable wasn't installed badly - I know, I installed it!!

Thanks for the heads up on the IAW bit though. I didn't know that.