Are you inquiring about a back plate within an enclosure? If referring to BS 7671 I’m thinking Regulation 527.1.1: This reg aims to minimize the risk of fire spread. 416.2, focuses on preventing live contact and generally Regulation 522, external influences.

Edit: I think BS EN 61439-2, switchgear etc

- Andrew

Hi Andrew.

Many thanks for your reply. Yes correct I meant backplate within the enclosure. Does the material has to be steel? 

Hi Andrew.

Many thanks for your reply. Yes correct I meant backplate within the enclosure. Does the material has to be steel? 

The reg that explicitly mandates the use of non-combustible materials is Regulation 421.1.201, which applies to domestic consumer units and similar switchgear assemblies. The requirement for non-combustible materials may vary depending on the specific installation context. Does the material have to be steel ? I don’t think so.