Trying to keep the job as simple and cost effective as possible, whilst getting the shower working and safe. But bearing in mind the house is going to be sold in the next 12 months and as it's in poor condition likely to be gutted.
It's connected with 6.0/2.5 cable and protected by a 32 amp type B circuit breaker. The cable laid across joists and insulation in the loft space, the insulation is at the same height as the joists, therefore the cable is touching it.
I am unsure which installation method to use in the cable calculations, using table 4A2
- The table considers many scenarios where the cable is clipped to a joist, contact with the ceiling or completely buried but not just sitting on top of the insulation.
- Worst case is assuming it's buried or will be buried with method 103 and a current rating of 23.5 amps which means upgrading the cable.
- If I use the numbers for 100 or 102 I am ok
- The insulation is about 150mm deep, therefore I am ok for when the cable runs through it.
I don't want to use numbers just because they work but also i want to avoid a lot of unnecessary complexity and cost.
The CU just has CB's and I will need to run bonding in the bathroom which is fairly straightforward.
I am also concerned that there is about 1m of cable concealed in a partition wall and buried by less than 50mm not protected by an RCD or any other method. My interpretation of the rules are that as I am just changing an appliance other than for things like bonding and current carry capacity I don't need the existing installation to comply with the latest regulations, is this correct?
Then out of interest for new installs I assume when cables run the same direction as joists they are just placed on top of the plasterboard before insulating or pinned on to the joists, what happens when the cables need to run perpendicular to the joists?
Thanks
Alan
