hygroscopic pvc

[maguire]

Any one know where I could dig up information on the hygroscopic nature of pvc cable I have a client who owns several statics,last year I did a full inspection on them but this year some of them have very poor IR on the ring and lighting circuits these are unheated most of the year and the ground is unmaintained untill May, long grass overhaning trees etc I have tried to tell him that damp is always an issue and that is reflected in the readings but he seems unconvinced if I could find some info it may help
DM

 

[Adam_151]

I'd be more inclined to beleive in the effects of damp on the accessories rather than the cable

 

[maguire]

That is true as last year he bought a additional van and the IR was terrible changed all the sockets and light switches and it improved hugely
but on the vans that are failing they were changed also but I take your point I may have to cut back to clean copper cheers
DM

 

[tonyelectric]

PVC is a non-hydroscopic substance, it cannot absorb water so that is definently not the problem, dampness in fittings is far more likely the cause.

 

[holmslaw]

..

 

[JohnD]

tuning on the heating will be better than changing the accessories. Most likely it's just cold and damp.

 

[bernardgreen]

Not sure if PVC is hydroscopic but I have had to replace a long run of PVC cable that had been under water for several years due to excessive current leakage between conductors. That definately suffered from moisture penetrating the PVC sheath and insulation on the conductors. Water depth was about 8 feet so about 3 lbs per square inch of pressure in the water around the cable

( not mains cable so please no comments about not to BS xyz1 )

 

[RF Lighting]

I wonder why all those PVC insulated concentric DNO feeders sat in the wet ground for years and years dont keep exploding left right and centre?

 

[1john]

Different grades of PVC perhaps, the outer sheath of an SWA cable does not feel, cut or strip the same as say the PVC on a twin and earth cable.