PVC twin & earth & water

[jedisparks]

Evenin all

Just a bit of an odd ball question here following a discussion i had today.

PVC twin & earth - If it is exposed to moisture or is laying in water over a long period of time, can this have a deteriorating effect on the cable sheath

Many thanks

 

[telectrix]

all depends what's in the water. acid attack or similar will cause deterioration. in pure water it will be a long timee before you notice anything.

 

[Des 56]

None at all in my opinion

Even the water industry use pvc for piping because of its unpenetrability,(that was a nicely made up word)

 

[Richard]

I read somewhere that cable is classed as submarine. Don't ask me where because I have no frigging idea!!

 

[nickblake]

None at all in my opinion

Even the water industry use pvc for piping because of its unpenetrability,(that was a nicely made up word)

like it just written that one down

 

[PC Electrics]

Unlike nylon and some other plastics PVC is almost totally unaffected by water. Indeed, one of the reasons why PVC is such an environmentally unfriendly material is the extremely long times it takes the material to break down ('000s of years). Automotive manufacturers have been undergoing PVC reduction programs over the last decade or so for this reason - it's why you've started to see the return of leather trimming.

 

[jedisparks]

Yeah thats what I thought. SWA has PVC sheath, although tougher than that of t & e generally and it lays in the ground where it is wet.

The guy who i was speaking to seemed to think that it will rot in water over a period of a few years.

I think he may have been a muppet.

 

[nickblake]

Yeah thats what I thought. SWA has PVC sheath, although tougher than that of t & e generally and it lays in the ground where it is wet.

The guy who i was speaking to seemed to think that it will rot in water over a period of a few years.

I think he may have been a muppet.

Fozzy Bear i think matter of years ask him the question how long has suppliers under ground cable been PVC its over 40 years now !!

 

[jedisparks]

Exactly. The whole point of using PVC is its properties of durability and as according to Des 56s' new word "Unpenetrability".

 

[Rappid]

I looked at a job last week, security light broken by kids football, they had run T&E for the light, part laying in the gutter and part clipped to the wall, outer sheath was cracking and brittle. Was gonna replace it with some Hi-tuff I had laying around or would it be cheaper to use a length of black 3-core flex?

 

[jedisparks]

Interesting. But could that have been down to exposure to sun rather than water?

 

[jaresquire]

Sun/paint/creosote and nearby glue sniffers more likely than water IMHO

 

[telectrix]

black flex will be fine.

 

[ian.settle1]

Yeah thats what I thought. SWA has PVC sheath, although tougher than that of t & e generally and it lays in the ground where it is wet.

The guy who i was speaking to seemed to think that it will rot in water over a period of a few years.

I think he may have been a muppet.

Which one?

 

[IQ Electrical]

I looked at a job last week, security light broken by kids football, they had run T&E for the light, part laying in the gutter and part clipped to the wall, outer sheath was cracking and brittle. Was gonna replace it with some Hi-tuff I had laying around or would it be cheaper to use a length of black 3-core flex?

That sounds like UV damage, the twin & earth sits there happily for years in the sun but come to change the floodlight and it falls apart.

 

[MarkieSparkie]

Evenin all

Just a bit of an odd ball question here following a discussion i had today.

PVC twin & earth - If it is exposed to moisture or is laying in water over a long period of time, can this have a deteriorating effect on the cable sheath

Many thanks

Hi jedi, The water will not have a deteriorating effect on the PVC material, however, the PVC insulation of T&E and other cable is not totally impervious to water penetration (GN1, 4.5) and some water will be absorbed over time, the deeper the cable is submerged in water the faster the rate of penetration. Where water resistance is required polyethylene or polythene (PE) is used for the insulation material, on telecoms, data transmission, and instrumentation cables. When PE is cross-linked (XLPE) to improve it's thermal propeties it becomes suitable for power cable applications eg. XLPE SWA cables.
For use in extreme situations the cable manufacturers make sub-marine cables, with extra thick insulation for pressure resistance.
Generally, exposure to moisture does not lead to water penetration. Even continuous exposure to a few inches of water will take months for penetration in my experience, but given sufficient time it will happen.

 

[oxocube]

PVC cables are not suitable for continuous immersion in water.

 

[truckster]

None at all in my opinion

Even the water industry use pvc for piping because of its unpenetrability,(that was a nicely made up word)

Not sure if applies to PVC, but I've known women with the condition!

 

[Rappid]

Interesting. But could that have been down to exposure to sun rather than water?

It was quite an old cable, cores was red and black

 

[Engineer54]

Standard Building wire insulation is in fact microporos, not sure about the sheath on T&E. It will let minuet traces of water through the PVC over a period of time. The deeper the cable/wire is submersed then obviously the higher the pressure on the microporos covering, letting more water to pass through.


Not all PVC is the same, the cable makers use different additives and enhancers to suit the grade and type of covering required. There is indeed totally impervious to water PVC coverings, but it isn't your standard building wires/cables. Sheathing by the way, is a totally different PVC make-up to insulation PVC.

 

[jedisparks]

Which one?

The guy