Regulations for mains cable through outside wall

[mmmark]

Should cable be within a conduit/plastic pipe etc where it passes through a cavity wall? We are having an Air Source heat Pump wired in and it looks like the cable passes directly through a hole drilled in the outside wall without any type of protection. Is there any regulation governing this?
Also the electrician also knew the cavity was to be later filled with polybeads. Does these EPS (polystyrene) beads pose a risk to the unprotected cable insulation?
Thank you
Mark

 

[boballum]

yes cables should be protected in conduit when going through a wall, the polystyrene will have a detremental effect on the cable. Breaking down the plasticiser in the PVC coating there is a section in the regs that covers this

 

[mmmark]

Common sense says the cable should be protected when going through a wall but how can you point me in the direction of the regulation? Is there a way of viewing these regulations on line somewhere?

 

[boballum]

mine are in the office I will find it and let you know....as far as i'm aware there is not an online version

 

[boballum]

Take a look at Q & A of the Day – PVC cable in conduit when passing through polyurethane insulation? - Voltimum UK - Electrical Installation Products and Contracting this confirms that polystyrene has a detrimental effect on PVC, also there is a de-rating factor that has to be applied to the cables as well when they run through insulation better make sure they have allowed for this, a cable totaly immersed in insulation for 100mm requires a de-rating factor of 0.78