ProDave

Almost all supplies to new properties now are PME, Protective Multiple Earthing, a variation on TNC-S The "earth" comes in combined with the neutral usually on a concentric cable. A know (and not that uncommon) failure is the combined Neutral and Earth (CNE) conductor breaks or corrodes. In this situation the "earth" in the property can rise well above local earth potential. For this reason, wiring regs prohibit a caravan being connected to a PME earth. On the other hand the SWA must be earthed at source. So in this case you do not connect the SWA at the caravan end and you do not connect in any way to the PME earth. So no need for 3 core SWA. Instead you provide a local TT earth with an earth rod.

Just use 2 core SWA for the caravan. For the treatment plant take it's own SWA straight from the garage CU

A lot of the suppliers of KwikStage state the kit they sell would for instance do a 12 metre run with two platorms with a working height of say 5 metres. That will give you a good idea of how much you need.

I would not connect to that cable. Follow where it goes, it will almost certainly go to a small consumer uit inside the 'van. Strip back the SWA and cut the armour back and insulate it so nothing can contact it, and take the inner cable of the SWA into the 'van and straight into the consumer unit. Then drop an earth cable out from the consumer unit to an earth rod as close to the 'van as you can get it.

You WILL need to earth both SWA's at the origin. At the CARAVAN you do NOT use the earth. Use an insulated gland so the SWA does not terminate to anything, and the caravan will need it's own TT earth (earth rod) Agreed do not use the 2 tier henley blocks.

The issue would be certification. What timber are you using? is it the right spec? who is going to declare the loading? I would have no problem doing that for a shed or other building that did not need BC approval, but for the main joists of a house? I think not.

Or a further alternative. Get them to agree to you burying a length of cable ducting up your plot passing over the buried 11KV cable at the rime the 11KV cable is installed, through which you will later pull any cables you want with no need for excavation at that point.

Two things strike me. Why does the branch have to come from the same place? Would it be possible to take the branch from where the crossing line passes your left boundary. That WOULD mean an extra pole at that point, but that would avoid the orange cable passing under your land across the plot and remove the issue, so would that be a price worth paying? The other, is if all you want to bury is a cable for the solar PV, just do it. the 11KV cable will be a lot deeper than you need to go for an LV cable, just hand dig that part to be sure.

Normally with UFH you would have one thermostat per room, so one for the open plan downstairs, one for each bedroom and one for bathroom. I would not like to comment on how well, if at all, Nest thermostats would connect to the UFH manifold controllers. some expect a normal thermostat, some have their own standards and need their own thermostats.

The key thing with ground like that is get the foundations in now, while the ground is dry. If the water table then comes up in winter it won't matter. This garage foundations is basic stuff for a builder. Perhaps mention when talking to contractors about the garage that you will be building the cabin and eventually a house so you hope to find a reliable builder that you can work with and they might be more willing to be agreeable. Post any quotes you get here before you accept them.

^^ That is meant as an END profile, not for the bottom.

No 1 tip, for something like this where you have to cut the panels to size and cut holes in them, template it with a large piece of cardboard and cut it from that: Corner trim and end trim on the two ends. Do NOT use the multipanel bottom trim. Others agree that it is a stupid design that leaves the bottom of the panel sat in water. Instead finish the panel a few mm from the floor or shower tray and seal under the gap. Run the panel down onto the shower tray, do not run it down behind and then put the tray in front, that is a recipe for leaks. The trim panels are barely 1mm thick. Do not worry about them making things out of square. They are insignificant. the wall will be out of square / out of true by much more. Finished result:

The bottom line is the FIT has gone. You CAN still get an export payment, the best on offer seems to be 5.5p per kWh and for that, the system must be installed by an MCS engineer and you must have a smart meter to measure export. Rough guess 10.5kWp is going to generate about 6500kWh per year so you would get paid about £360 for that. The payback time is just way to long. Not viable on that basis. I still believe PV is only viable now if you can get the kit very cheap and self install and then self use most of what you generate. On that basis I am expecting a 6 year payback.

GU10's for me. If you choose anything else, make sure you keep plenty of spares, because my worry is when they fail in 5 or 10 years time, you won't be able to buy identical replacements.

I I have roughly 25M in total of 22mm pipe in the ASHP circuit and I could not achieve the required flow rate just with the pump built into the ASHP. I had to fit a second external pump to get the flow rate high enough for the ASHP.

Surely these exist as a bodge to "fix" a dodgy drainage system? Properly designed they should not be needed. Would a waterless trap do the same thing?

It keeps coming back to the "small" kitchen. I would seriously consider making the left hand living room window a little narrower, and moving the pocket doors half a metre to the right. I suspect that will make the flow around the island a lot better.

The stairs are always going to be enclosed between the 2 walls upstairs, no matter how much you move them forwards or backwards to accommodate the downstairs WC If you want to retain more open downstairs, how about taking a bite off the utility room for the WC, still accessed by a door under the stairs, but no headroom issues.

On any circuit with an RCD, shorting neutral to earth will cause some of the neutral current to go to earth instead and the RCD will detect the imbalance and trip. That is normal and something you just learn to accept if you cannot or do not want to isolate all circuits. The Bang and the MCB tripping could be anything. It won't be a USB device. It could be a faulty extension cable or could equally be a fault on the circuit such as a live wire pinched by a screw and on the verge of the insulation breaking down. That's why you should do a high voltage insulation test on the wiring that will find that sort of fault.

I wish roofers would do that. I HATE slated roofs with the slates nailed direct to sarking board and all over the inside there are nails poking through.

That reminded me of this classic

With hindsight, it would have been a good idea to paint the outside face of all those logs before assembly. Now you have to perch on a ladder resting in the stream.

Making the hole for the tap and basin waste will be a challenge.

I used 15mm for everything including the showers and the bath, to minimise volume of water until hot reaches the tap. No problems with flow rates. What is your mainspressure and flow like? that is what will drive it. But do make sure heating loops from ASHP to manifolds and HW tank are large and short. ASHP's in general seem to like high flow rates and I had to fit a second pump to get a high enough flow rate through the 22mm pipework. 28mm would haqve been better.

This is what I have just done for ours. Simple frame of painted wood. The "worktop" at the moment is a sheet of multipanel, left over from the other bathroom, and in this picture missing it's edging strips as everyone is out of stock at the moment. The basin was £45 from B&Q before discounts, I think I paid £38 in total for it. I forget where the tap came from. but B&Q did not have a tall mixer tap to go with the basins they sell. That might not be the permanent worktop. We wanted this one https://www.wickes.co.uk/Zenith-Rouille-Laminate-Worktop-12-5x600x3000mm/p/148757# That is one of the trendy thin kitchen worktops. Unfortunately at the moment Howdens only stock grey or grey. We like that one but it's pricey and at the moment Wickes won't deliver it and it's not in stock anywhere in Scotland. So the Multipanel offcut will remain probably for a while, who know, forever?