Good afternoon, I hope you are all well.
Firstly, I am not an electrician, but I am trying to save a lot of disruption all at once if I can.
Here’s the reason for the question. A couple of years ago I had a new Hager consumer unit installed by an electrician and had it fully populated with RCBO’s at my request. one RCBO for each circuit. It also has one main isolator switch. I have recently decided that I now want to re-organise the ring final throughout the bungalow. To achieve this I would like to do most of the installation myself one room at a time to avoid major disruption all at once. The bungalow is a small 2 bed with wooden floorboards covering 78sq/m approx. Under the floorboards there is an an 18inch deep (approx) void.
My initial thoughts are that I could run all the cables required for an entirely separate and new ring final, (not connected to anything) so an electrician can come in and connect all the new sockets and the new cables to the consumer unit when ready, and at the same time disconnect the old ring final. Thus, swapping old circuit to new.
As these cables will be run under the floor and cannot collapse on to anyone during a fire, are they still required to follow the new regulations and be secured to the underfloor joists with metal cable clips, or can they run free on the ground under the wooden floor as the existing cables do now.
My personal opinion is that a fireman would prefer to potentially step on resting cables, rather than step through clipped suspended cables if his or her foot were to go through the floor in this situation. Also from what I have read it is more desirable, thermally, to have cables in free air as opposed to being fixed or covered However, I would be grateful for your expert guidance in these matters.
Other information which may be relevant:
Cable to be used will be 2.5mm twin and earth( 2x2,5 and 1x1.5cpc)
The new ring final will have 12 double sockets in total, inclusive of 2 spurs. 1 spur will be terminated at 1 socket in a bedroom, and one spur to be terminated at the RCBO in the consumer unit to ensure that there will be no junction boxes under the floor.
I know it’s not pretty, but the new cables will come up through the floorboards into short lengths of 38x25 plastic trunking (approx 8inches long) and then into surface mounted 25mm deep click mode pattresses and sockets. For fire considerations, the trunking will be fixed to the wall with screws into brick (no plastic rawlplugs). A neat cut-out will be made in the skirting board to ensure trunking meets the floorboards. Also for fire considerations, the cables in the trunking will be restrained by a safe-d metal cable clip.
The pattresses will be attached to the wall with 3 screws. Two with plastic rawlplugs and one directly into brick for fire considerations.
I hope I have given you all enough information to go on, and wish you all well.
As always, many thanks in advance.
Simon
