Plastic blanks or dummy MCB's on metal consumer units

That's Wylex for you!

All you need is IP2X and blanks that can be removed only with a tool. I'm not keen on the Schneider blanks and for me, the best are the “dummy” MCBs - they aren't going anywhere.

But does it really matter if the blanks are a fiddle. You could always secure them with a bit of chewing gum, putty, or Blu-tac.

I use a length of insulation tape behind the lid to hold the metal blanks in place. As to what sort of thing to blank with, that's largely down to what the manufacturer recommends, to maintain non-combustibility etc.

There was a thread a while ago which pointed out that the metal blanks were non-earthed exposed-conductive-parts. Go figure!

Doesn't the hinged metal cover form the “fire barrier”? I fit the main consumer unit cover and then fit the blanks after. It is much easier.

Z.

Just buy the Fusebox module blanks instead of the metal blanks problem solved.

MCBs and RCBOs are made from the same plastic as the blanks but it’s the metal enclosure that is supposed to contain the over heating.

Pardon me for being so bold, but I am sure that plastic blanks are compliant so long as the metal lid hinges downwards. I have never bought metal blanks separately and have only ever fitted whatever spare plastic blanks which either came with the unit or some from my spares box.

In any case, the number of '17th ed' boards I have seen fitted where knock-outs have been randomly bashed out and cables run in without glands or grommets numbers many, along with those whose knockouts have been opened up but left unused! Given this, worrying about whether a blank is of metal or plastic is something not worth the concern in my view.

 - RE: Schneider, I have seen a significant number of their units fitted whereby the metal flaps hinges from the bottom! Don't know if this was a design fault, or that someone fitted the front on upside down!

Wylex sell plastic blanks, so i am pretty sure they allow the use of them in their boards.

Colin Haggett: 
 

MCBs and RCBOs are made from the same plastic as the blanks but it’s the metal enclosure that is supposed to contain the over heating.

The requirement is that the consumer unit should be metal so it doesn't catch fire.  There is no requirement to contain anything.

Or actually have their enclosure manufactured from a non-combustible material. Pretty sure it’s not for fire on the outside so where is the risk of combustion coming from other than inside.

Nick Bennett: 
Wylex sell plastic blanks, so i am pretty sure they allow the use of them in their boards.

Both are available.

https://www.screwfix.com/c/electrical-lighting/consumer-unit-accessories/cat8030002#category=cat12670004&brand=wylex