smart51

Some success. The landing light now works without tripping the lighting circuits. Well done everyone who said borrowed neutral, and thanks. I'm 6 hours in today, lifting floor boards on the landing and in the loft, drilling through joists, a floor and a ceiling to get a neutral wire from the hall pendant to the landing pendant and it all works. I've just got to clip the wires to the inside architrave of the boiler cupboard and put back all the boards. Luckily, the carpets are all up and the fitters are coming tomorrow to lay new carpet. We've not moved in yet, so I don't know when the sockets circuit tripped. But when I got there this morning, the front sockets circuit had gone. I think it has a problem of its own which is perhaps marginal, so sometimes it will work and sometimes not. Somehow the lighting circuit tripping tipped it over the edge yesterday.

I cut through the boards and insulation in the loft this morning to look at the wiring to the landing light pendant. There is a ring that goes in and out with the light bulb connected to the neutral. There's a third twin and earth with both red and black going to the light bulb live. This appears to go to the landing light switch common. The landing light switch S1 and S2 are wired to the stairs light switch S1 and S2. Would I be right to separate the ring from the landing light, then take a neutral from the hall pendant up into the loft and connect that to the landing light?

Yep. Switch off the landing light. Remove the bulb. Reset all the trips. Refit the bulb without switching it on - the front sockets circuit trips. Switch on the landing light, the downstairs light circuit trips.

The third switch is by the front door and is for the hall light. The common on this switch is connected to both the red and black of a twin and earth. The common on both the switches at the bottom of the stairs is connected to both the red and black of a twin and earth. I take it this is common practice if you really just want a single wire. So if you wanted to connect all three terminals of two switches, you'd connect red to S1 and black to S2 of both switches, then have a 2nd T&E and connect both red and black to the common of both switches.

This is the upstairs switch. All as expected. This is at the bottom of the stairs. Left switch is the landing light. Right switch is the hall light. Back left terminal is live and neutral from the RH twin and earth, plus live from the front right terminal. Front left and centre are N and L to the upstairs switch. this is the mother load of 5 twin and earth with PVC tape and everything. The ceiling rose just has red, black and earth coming into it.

Is it DIYable? I'd guess I've have to find where the errant neutral comes from and remove it, then find where the live comes from and connect its neutral.

The electrician is an employee of the firm of builders who are doing the rear extension. We're stuck with him until he will sign it off, which he wouldn't do with the old board.

The landing light is a culprit. With the bulb removed, the lighting circuits stay on. I've had all the downstairs lights on and off and it seems stable. Anyway, I've had the cover off the board and found that the unlabelled way is used and is for the sockets in the front rooms. With the bulb in but switched off, the socket circuit for the front room trips. What's that a sign of?

The decorators knocked off everything with lights in the name. They're papering two of the ceilings and wanted to remove the light fittings.

It is the MCB that is tripping, not the RCD. There are decorators in at the moment so don't want to knock the power off to remove the cover. I'll do it later when they're done. This is the new board from the outside.

We're coming to the end of having an extension built. Their electrician has wired it all in but said he cannot sign it off unless we have him replace the fuse board with RCDs at an additional cost. We agreed and he did it on Friday. On Saturday, we found that the sockets at the front of the house have no power and the circuit he labelled as downstairs lights is tripped and won't reset. His reply to my email asking about this was more or less '£90 per hour to fault find, min 4 hours'. With all the lights off, if I reset the RCD for the faulty light circuit, the other light circuit trips as well. For the sockets, there is only 1 circuit labelled on the box. All the sockets in the back rooms are good. All the ones in the front rooms are off. This seems odd to me. I wonder if the spare way on the board is the other sockets and he's not labelled it. That RCD won't reset. I'm an electronics engineer, though not an electrician. I'm safe to disconnect things and reconnect them. So what's a good procedure to track down where the fault is?

The third builder was the one we were recommended by a neighbour. His quote came in today at £62k. He won't be getting the work. The £48k quote was from https://probuild360.co.uk/ They are a big firm that run several jobs concurrently, so they said. So their ground works team come in and do their thing, then the bricklayers, then the plasterers etc. The £25k people are https://theaffordablebuilder.co.uk/contact.html £25k is suspiciously low. The mid price quote might be the winner.

All three were given architects drawings that specified materials. All three did a site visit and I gave them the same information. The expensive one wrote to us when we got planning permission. The cheap one is called "affordable budget builder Ltd" and put a leaflet through the door. The other was a recommendation from a neighbour.

We've had two quotes in and are waiting for a third. We're having an 18m2 rear extension built, but the new pitched roof will also replace the flat roof on the 10m2 kitchen and having the kitchen replastered. Lets say the equivalent of a 23m2 extension. The two quotes so far are £25k and 48k. One seems a bit steep and the other surprisingly cheap. The work briefly comprises new footings, a brick wall to the side, 5m long bifolds at the rear and a pitched tiled roof. Internally, wet plastered walls and painted. Tiled floor, 9m2 of slabs outside. We've asked them to redo the soffits on the house while they're here. There's nothing particularly fancy or difficult. How do you choose between radically different quotes?

I'm sure you know. WC improves the CoP of the heat pump by reducing the flow temperature in mild weather. I'm slowly setting up my WC curve. Typically, the weather has warmed up. I could do with a couple of cold days to do further tests. I'm setting the WC curve to be a balance between the house sitting at the desired temperature by lowering the flow temp, and our wish for it to be cooler over night and then warm up in the morning. I've found that setting the flow temperature that would give an equilibrium temperature of 22° allows the rooms to warm from 18° to 20° in a reasonable time. The limitation is I can only set one WC curve. The living room has huge solar gain and is always a degree or two warmer than everywhere else. Even if I had the flow temperature lower, the stat in the living room would turn on and off.