Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, about the fitting of consumer units on MDF board and its fire safety, is answered by the NICEIC, the ECA and SELECT:
Attached is a photo of a 17th Edition board taken from Google images with the mounting board and an opening to show what I mean. The only regulation that I can find close to what I need to know is BS7671:2008 - 134.1.6 - 'Electrical equipment likely to cause high temperature or electric arcs shall be placed or guarded so as to minimise the risk of ignition of flammable materials'.
Does this mean that if the wooden cut-out is larger than the opening on the back of the cooker control unit, this would reduce - if not stop - any sparks coming into contact with the mounting board, and would meet all requirements to BS7671:2008?
NICEIC answer: It is a question of preserving the integrity of the consumer unit as this affords, by its construction and material, protection against the risk of fire to the surface to which it is mounted. If this integrity is significantly compromised during erection, for instance by making a large opening to the rear for cable entry, the surface to which it is mounted may be exposed to a risk of fire. Remember, if the cable entry in the consumer unit is fire stopped, you can mount it on any surface you like.
ECA answer: I have not seen the NICEIC DVD, but I would say that back entry consumer units can be mounted on other fire rated building fabric materials; perhaps not MDF.
SELECT answer: You can secure surface-mounted consumer units on to wooden back boards. However, the amount of back plate removed should be restricted to ensure that the unit remains a suitable enclosure for unsheathed cables. In simple terms, the hole in the unit should be smaller than the hole in the backboard.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link:
www.voltimum.co.uk/consult.php?universe=consult.index.questions