TonyT

I would stick with multi panel, utilise good quality sealants and re do it again in 10 years. maybe invest in a shower tray with an upstand?

Turn the power off and tighten every screw terminal, relay terminal, din rail terminal etc to remove the probability of a intermittent cable fault.

Ok just trying to point you towards an alternative, it’s not an issue if you want to buy a more expensive version, your link is for a 12 volt version, mine is for 48volt.

These have been out for years. favoured by many on the old Navitron forum

https://www.ebay.co.uk/itm/223639790102 you can buy them cheaper, so lots cheaper than £30,£50K

Wasn’t that if it was more than 500mm you had to half the Current carrying capacity of the cable as a general rule of thumb

While the regs give guidance on derating cables totally surrounded by insulation for more than 50mm length in insulation. I think I wouldn’t bother worrying about it, I wouldn’t want mains cables next to data cables( wired video door bell springs to mind) but would just make sure they are sealed as per ProDave’s method.

The vapour barrier would go on before the plasterboard , stapled to timbers and joints taped , lapped etc failing that 2 coats of emulsion is deemed to be a vapour barrier, so crack on with the insulation

Hot air gun?

Can it not be encouraged to follow a tighter contour without damage to the pipe with some all round band?

Once you have the connection, make sure your electricity supplier is different from your DNO and crack on

Tell them you have gone for oil. get the £3k connection and fit the inverter ASHP.

Condensation from the stack?

My EV charger has a selector switch on the side to limit current, it can be set to various lower current settings might be helpful in situations like this

Have a look at DW144 use in conjunction with manufacturer info.

Get an approved contractor to do the work, I had a contractor do some 11kV work for me at work and Scottish Power witnessed the dig, cable jointing and testing and then they carried out the point of connection and then adopted the cabling/works to a certain point. Ask UKPN for a list of contractors

Generally easier to find the centre of the wall mark a vertical and horizontal line with a spirit level, then take measurements to outer edges and pipe centres. transpose these dimensions onto the wet wall, by doing the same starting from the centre mark

That’s so they can change the clients name and pass it off as new work and get paid 100% again from the new client, few changes bish bash bosh

Is the existing loft hatch fire rated? if so change for like for like or one with better thermal properties.

They aren’t run in the cavity, just pass through the cavity as you say so fine, if I knew I was going to be doing cavity fill I may look at a way of protecting cables from polystyrene to stop the green goo issue later

Cables shouldn’t be run in the cavity, the only exception is tails passing from the meter box to the consumer unit.

Good choice

And put things like fridges, boilers on their own circuit, so nothing else can affect them, ie it’s only a fault on that single piece of equipment/circuit that can trip that circuit. all about minimising future inconvenience at the design stage.

Condensate pump can collect and pump a longer distance if required.