Rubber grommets for knockouts

[jpadie]

I'm using some Screwfix surface mounted pattress boxes to add some sockets to a ring main in the garage.  These are they https://www.screwfix.com/p/lap-2-gang-surface-pattress-back-box-32mm/29047?ref=SFAppShare

 

 

 

The manufacturer data that came with them says to use rubber grommets for the knockouts. But LAP don't make any such grommets and I've not idea how they would fit to the knockouts for flat cable.  

 

 

 

Any thoughts on these?  Are they a regs requirement?  Could I just fill the 1mm gaps around the cable with silicon or another filler?  I think the plastic is far weaker than outer insulation on 2.5 t&e so I can't see abrasion being a big

issue. 

 

[Onoff]

I've never fitted grommets to that type. Just knock out and file down any sharp edges. 

[Chanmenie]

Those boxes are not designed to have grommets 

[FuerteStu]

If they are round knockouts, you could use a stuffing gland for cable entry. 

 

Far cleaner looking, and at least helps the ip rating

[Onoff]

1 hour ago, FuerteStu said:

If they are round knockouts, you could use a stuffing gland for cable entry. 

 

Far cleaner looking, and at least helps the ip rating

 

They're these:

 

 

Hilarious that the LAP instructions say to use rubber grommets. LAP btw are a Kingfisher (they own Screwfix), own brand.

[FuerteStu]

19 hours ago, Onoff said:

 

They're these:

 

 

Hilarious that the LAP instructions say to use rubber grommets. LAP btw are a Kingfisher (they own Screwfix), own brand.

Absolutely despise these patresses. 

Crumbly sharp cable entry points, the slightest knock and they crack.. Even mounting on an uneven surface and tightening the screws can cause them to implode! 

 

[G and J]

1 hour ago, FuerteStu said:

Absolutely despise these patresses. 

Crumbly sharp cable entry points, the slightest knock and they crack.. Even mounting on an uneven surface and tightening the screws can cause them to implode! 

 

+1

 

With a passion.