Electric cable and EPS

[jfb]

Does anyone know what you have to do when making sure cable doesn't come into contact with EPS? Does there need to be a gap of minimum 20mm, 50mm,? Or if I tape some membrane (say like intello) to the eps can the cable rest against the membrane?

[PeterW]

Use trunking and the problem goes away. 

[Jeremy Harris]

Best bet is to either put the cable in ABS trunking or conduit, so it's kept well away from the EPS by a barrier that won't allow the PVC plasticiser to affect the EPC,  or use non-PVC cable where it has to run through EPS (NYY-J is OK running through EPS, for example).  Cable ducting is also OK running through EPS, as it's usually made from something like PE.

 

Whether a thin membrane would be impervious to the plasticiser in PVC cable I don't know.  It's not something that's in the spec for the stuff, and personally I'd not risk it. 

[jfb]

sounds very sensible and i have some  trunking spare so will use that. thanks

[phatboy]

Let's say, 'someone' didn't know about the risks at the time, and the EWI installer didn't mention it before going ahead.... Is there a likely timeline before it causes an expensive issue?!

[Jeremy Harris]

28 minutes ago, phatboy said:

Let's say, 'someone' didn't know about the risks at the time, and the EWI installer didn't mention it before going ahead.... Is there a likely timeline before it causes an expensive issue?!

 

What happens depends on a lot of variables, with time and temperature being the two most critical.  Worst case, the cable ends up getting very sticky and "melting" a channel in the EPS, as the plasticiser leaches out of the cable and attacks it.  Although sticky on the outside, the cable may end up getting brittle and if flexed there's a chance that the insulation might fail, but usually the damage seems to be mainly to the EPS and the outer sheath of the cable.

 

If it stays cool, then the chances are that it will take years before there's any serious degradation, but without ripping it off and looking at it it's hard to know what might be going on.

[phatboy]

43 minutes ago, JSHarris said:

 

What happens depends on a lot of variables, with time and temperature being the two most critical.  Worst case, the cable ends up getting very sticky and "melting" a channel in the EPS, as the plasticiser leaches out of the cable and attacks it.  Although sticky on the outside, the cable may end up getting brittle and if flexed there's a chance that the insulation might fail, but usually the damage seems to be mainly to the EPS and the outer sheath of the cable.

 

If it stays cool, then the chances are that it will take years before there's any serious degradation, but without ripping it off and looking at it it's hard to know what might be going on.

 

Well this is my situation.... the cables aren't ever likely to move now, and are behind about 90mm of EPS.  So also difficult to replace!

 

(Sorry for the thread hi-jack!)