Plywood backboard for BS EN61439-3 compliant consumer unit

For those who would object, what is the perceived concern ?

I presume that folk imagine that if there is a fire going on in the metal box, and we do not expect any fuse or circuit breaker to operate before the box ignites the wooden board ? I consider that to be most unlikely.  At the sort of temperatures that will ignite plywood (glowing red or orange perhaps) there are so many other problems that what the backing is doing the least of your worries.  A non- combustible backing, such as asbestos cement,  might make sense if that was the only risk, but there are other problems with that.

Also, how close to the edge of the non-combustible backing do you bring the rest of the installation - do you then mandate pyrotenax cables or steel conduit for the wiring and the use of solid metal light switches etc.  It makes very little sense to demonise consumer units without the rest of the installation.


Certainly the wiring regs have no objection, I think you would be compliant with '7671 even if the board was made from a sheet of solid rocket fuel, though it is not sensible for other reasons, not least as  screws tend to tear out ( the stuff being a rubbery consistency with oxidiser embedded).

For those who would object, what is the perceived concern ?

I presume that folk imagine that if there is a fire going on in the metal box, and we do not expect any fuse or circuit breaker to operate before the box ignites the wooden board ? I consider that to be most unlikely.  At the sort of temperatures that will ignite plywood (glowing red or orange perhaps) there are so many other problems that what the backing is doing the least of your worries.  A non- combustible backing, such as asbestos cement,  might make sense if that was the only risk, but there are other problems with that.

Also, how close to the edge of the non-combustible backing do you bring the rest of the installation - do you then mandate pyrotenax cables or steel conduit for the wiring and the use of solid metal light switches etc.  It makes very little sense to demonise consumer units without the rest of the installation.


Certainly the wiring regs have no objection, I think you would be compliant with '7671 even if the board was made from a sheet of solid rocket fuel, though it is not sensible for other reasons, not least as  screws tend to tear out ( the stuff being a rubbery consistency with oxidiser embedded).