Jeremy Harris

If you're fitting PV panels in the roof, then they will fit to flashing frames (rather like roof window flashing kits) that secure to the tile battens and the panels then fix to them. This has advantages over fitting them on the roof, i.e. over the top of tiles, in that it looks neater and it also prevents birds nesting under the panels. Panels fitted on top of tiles need to be fitted to frames, and this leaves a gap under the panels big enough for pigeons to get in and nest. We have some friends who are plagued with birds nesting under their panels, and last year they even managed to disconnect one of the DC connectors when raking out all the old nests, which entailed getting scaffolding put up to remove the panels, remake the connection and refit the panels. The cooling issue seems to be minor, as the in-roof kits have a lot of ventilation space underneath, and there should be a good flow of air up under the panels and tiles and out through the ventilated ridge vents.

You can easily work out the heat, as the switched mode power supplies used as drivers for LEDs are very efficient, never worse than about 85% and often over 90%. So, if you had an LED rated at 10 W, then the driver unit will dissipate around 1.5 W or so, not enough to worry about in the overall scheme of things - it will barely feel warm to the touch. I used over-sized switched mode power supplies for our LEDs, and even the largest of these barely feels warmer than ambient temperature after the light have been on for an hour or so.

This sort of explains how tragedies like Grenfell Tower happen. I wouldn't mind betting that there was a cosy relationship between building control and the appointed contractor, which resulted in nothing being looked at in close detail, just a glance that things seemed to be using the "right" materials (if that). I'm sure self-builders are seen as low risk by building control a a general rule, as we're investing a great deal of personal time into our projects, and that personal commitment alone is enough to make most self-builders want to do things properly, or see that they are done properly.

There's a pretty good (but a bit old now) comparison calculator between solar thermal and water heated by solar PV on Ed Davies website, here: https://edavies.me.uk/2012/11/pv-dhw/ I looked at fitting a mix of solar thermal and photovoltaic panels initially, but a few calculations showed that the true efficiency of solar thermal was well below that of photovoltaics when used for heating water all year around, even though the peak efficiency of solar thermal is better. The main problem is that solar thermal can only deliver sensible heat when the panels are hotter than the water to be heated. This means they start delivering power later in the day, and stop delivering power earlier in the day, than photovoltaic panels. It also means that there are many more days in the year when solar thermal panels deliver no useful power at all. The reason is to do with the temperature differential required to get a solar thermal panel to work. The panel always has to be a few degrees hotter than the tank, in order to drive heat from the panel to the hot water. With photovoltaic panels, this is irrelevant. Even if the panels are only generating a few watts of electricity, all of this can be delivered to the hot water tank, as long as the thermostat in the tank isn't satisfied and the electricity isn't being used elswhere. The icing on the case is the cost saving, both the very much lower capital and installation cost of PV and the virtually zero maintenance cost. Solar thermal needs maintenance checks every year, plus a high temperature antifreeze change about every five years, and altogether this pushes the cost per watt hour of useful energy delivered up to way above that a photovoltaic system. Add in the small FIT benefit, and photovoltaic panels are a complete no-brainer.

Mirrors my final inspection. I had all the certificates, bit of paper, etc lined up on the kitchen worktop for inspection, with spare copies for the BI. He never even glanced at them, let alone take the copies I'd printed off. He walked around, made encouraging noises about the wide doors and compliance with Part M, had a bit of a chat then left, saying that the completion certificate would be emailed to me later that afternoon.

I set up a cash account with TP, but the prices on the first few big orders I got them to quote for were so silly that I never bothered to go back to them again. By contrast, our local independent BM will try and price match anything, and if he can't will be open about it. As a consequence, they had around 90% of our business. Not only were they best value, but delivery was always free and, most importantly, they had the most intelligent and helpful delivery drivers of anyone that delivered to the site. I'd have probably paid a small premium just for the helpful drivers, TBH, given the hassle we had with so many other drivers ignoring our delivery directions given at the time of the order.

Mine were partially boarded then covered with fire resistant acoustic foam, the stuff used to line studios, as I thought that there might be some noise from there (it turns out this wasn't needed, really). In my workshop, the walls are lined with OSB and painted. Works well, in terms of being easy to fix things to, but OSB is a pig to paint, even with an airless sprayer. I found I needed to go over the OSB a couple of times with a roller to get the paint to get right into the crevices in the OSB. I think lining with MDF might be a better option. Still easy to screw stuff to, but also a lot easier to paint than OSB.

Our guys just scored the boards with a knife and long straight edge, then snapped them. The only sawing was when making the cut outs for sockets, switches, etc. The technique for marking these on the boards (provided the boxes have been correctly fitted so that they protrude into the board) is to cut the board to size. put it in position and then thump it where the box is. This marks the back of the board so that the cut out is in exactly the right place. A collated driver is a must, as you'll get thoroughly sick and tired of trying to do this single-handedly without one.

Traditionally boards were spaced off the wall on four ceramic or bakelite spacers. The only reason I can think of for doing this was to help keep the board free from damp. We've lived in old stone cottages with old meter boards mounted like this, and damp from the wall behind seems the most likely reason for having spaced it away. I've not seen a modern board spaced off a wall like this, and am guessing this is because we no longer build houses where damp walls are likely to be a problem.

I guess it would do a more thorough job on the lawn than the badgers, though................

You can normally run radial finals on 2.5mm2 up to 20 A (subject to any derating that may need to be applied if the cables are running in insulation). The limit (off the top of my head - I don't have the regs with me) is, I think, 50m2 floor area per radial final, so most houses would probably need around three or four 2.5mm2 radials, protected with 20 A (not 30 A or 32 A) MCBs or RCBOs. My 24m2 floor area workshop is pretty well flooded with outlets (currently there are 18 double gang sockets in there, so 36 outlets in total........), run on two radials, wired with 2.5mm2 and each protected with a 20 A MCB.

There's a French supplier of small kits for a wide range of tiny excavators, can't remember the manufacturer, but one is called La Sauterelle, I think. There are some YoTube video around, like this one: but if you can find the site they have a range of kits and just parts available to build them.

I couldn't agree more about the daft way that fire resistant domestic CUs have been mandated, when I'm near-certain the problem is really crap terminals. Some of the single screw terminals are pretty rubbish, and, in my view, need to be re-tightened after they've sat for a while and compressed the wire a bit. I wouldn't mind betting that crap connections were the true problem that caused this switch. I came across a glass filled plastic box a few weeks ago that met the fire test requirement for a domestic CU. Can't recall the make; not one of the big names; I was looking for a small waterproof enclosure to house a bit of kit and came across it by accident. I don't quite understand why the manufacturers have all switched to metal CUs to meet the new regs, when I would have thought they could have just changed the type of plastic they use and carried on making the old designs. I suppose it could be that their old moulds wouldn't work with a fire resistant plastic, but even so, I'd have thought it was worth the effort, given that they had to tool up to make new metal CUs anyway.

I've got a Lewden outdoor unit that we fitted as a part of the site supply installation. The nice thing about it is that it has a fair bit of room inside, which makes it easier to get the wiring laid out neatly. The Crabtree CU in the house was a PITA, as space is very tight.

That's one reason I went for an all-RCBO board. With RCD protection, in addition to current overload protection, on every individual circuit, only that circuit trips in the event of an earth leakage fault.

My counter battens were 50mm deep, hence having to use a bit of ply packing to bring 45mm boxes out far enough to protrude into the plasterboard, with no risk of a gap. With 38mm deep counter battens then that's an ideal depth to fit 45mm deep boxes directly, with them protruding half way into the plasterboard. What I did was use blobs of low expansion foaming glue (the Evostick stuff that cures in 5 minutes and comes in a gun cartridge) behind the boxes as sealant around the screw holes. This worked well, as the boxes tended to stay in position whilst the first screw was being put in, which makes it easier to juggle the screw, driver, box and torpedo level when getting the boxes spot on. The trick was to squirt a tiny bit of glue on the back of the box, wait a few seconds, then position it on the green board and wiggle it where you want it, getting it level as you go. Push hard, and it should stay where it is, leaving your hands free to pick up a screw and the driver and start screwing it into place. Hopefully, because the glue was around the screw holes on the back of each box, so the screw went through it, it helped to form a good vapour seal. I'd not bother faffing around trying to cut sections out of counter battens unless you really have to, as the vapour tight coating on the green board isn't that thick and could easily get damaged. Leading cables out through the nearest knock-out to a batten, and then clipping the cables tight up the rear edge worked well enough.

That's one reason that I drilled most of the holes and fitted all the noggins etc in place. I'd only have myself to blame if I screwed something up!

The problem with absolutely vertical runs over the dead centre of a box with the MBC system is that you really have to fix the cables to the counter battens - the green board in the photos is the vapour barrier. What I did was glue and screw thin ply spacers to the green board adjacent to counter battens (so that the 45mm deep back boxes protruded slightly into the plasterboard, with no gap). The boxes were then screwed (with sealant) to these spacers, tight against the edge of a counter batten, and the cables run out of the nearest top knockout to the batten and run vertically up the wall to the floor or ceiling void above. There's a slight offset from being dead vertical over the centre of each box, but all the cables do run within the vertical zone delineated by the box edges, so are OK in terms of the regs. I opted to not have any horizontal runs in walls anywhere, but run everything up and down to switches and sockets. The only exception to this was the speaker wiring in the living room, where I did drill through the counter battens and run it around the room.

It is indeed a load of baloney, as a part of the idea of DIN standardisation (i.e. all units that fit on a DIN rail, and within a DIN dimensioned enclosure, with standardised cut outs, are interchangeable) was to remove the ability of manufacturers to hold people to ransom by creating a series of monopolies, that tied consumers in to a particular brand, and so breach anti-trust laws. Given that the standards don't just relate to the dimensions of the modules, but also relate to their maximum allowable temperature, performance, fire resistance etc, there is no technical reason not to "mix and match". I still think it looks dreadful, and far prefer everything to be the same manufacturer, just for looks. However, take my workshop as an example. There is a DP RCBO, five MCBs, and three contactors in the same box. With the best will in the world I couldn't have used the same manufacturer for all of these, simply because some manufacturers don't make some of the components. They all fit perfectly, because of DIN standardisation, and all work OK, again because of standardisation. Interestingly, the manufacturer of the enclosure doesn't mention anything about what make of DIN modules have to be used in the enclosure, either. As the enclosure seems to have been made in Italy, they may well have been aware of the hot water they could have got into by making a statement that effectively contravened the whole rational behind DIN standardisation.

I still reckon it's a lot easier to just grease the studding and unscrew it afterwards. I've done this when fitting cast-in anchor bosses, with threaded inserts. I just greased up the threaded studding, screwed it into the cast-in anchor plate welded on nuts, poured the concrete, then unscrewed the studding a few hours later. No problem at all, the most tedious part was unscrewing the studding, as even with a power drill it took a while to unscrew a foot or so of 12mm studding set down into a concrete anchor block.

Any DIN rail bit of kit can be fitted in a box with a DIN rail, the only slight issue is with switched line busbars, as some manufacturers position their terminals at different heights. Not insurmountable, as you can get stepped busbar connectors, anyway. There's a mix of stuff in my workshop box, a DP RCBO on the incomer and SP MCBs feeding the line side of DP contactors. Off the top of my head I think there's at least two different makes of kit in there, maybe three. The manufacturer-specific stuff applies to oddball CUs, like the Crabtree Starbreaker series, that use a proprietary plug in busbar, that nothing else (AFAIK) will fit. There's also the issue of aesthetics, in that a row of MCBs that are the same make look neater. Other than that you can mix and match, as long as all the connections are OK and safe.

My guess is that you may need to look at using an industrial type metal switch gear cabinet, rather than a domestic CU. The advantage is that you can fit all your home automation switch gear in the same cabinet, as long as it has the required separation barrier between the ELV and LV circuits. IIRC, this is the solution that @jack has used, a large wall mounted industrial type housing. An alternative may be to use two domestic CUs, but I reckon it could end up looking messy. Compliance with the regs is easy enough, you don't need a box that's advertised as "17th Ed compliant", as you can make pretty much any board compliant by just wiring it correctly.

The need for an industrial size CU is one reason I think most stick with ring finals, rather than radials. I like the idea of radial wiring a lot, but there is no doubt that it does need a lot of wall real estate to house the kit, and allow room for all the cables to come in neatly. My workshop is radial wired, with contactors to remotely switch circuits, and emergency stop switches that kill the contactors, but even that used a pretty big box, just for two lighting circuits and three power circuits, by the time the contactors were fitted.

I arranged all our sockets and switches to be adjacent to counter battens, so all the runs were in safe vertical zones. My thinking was that someone was far more likely to either drill into a counter batten to fix something, or into a clear bit of plasterboard to fit an expanding plasterboard fixing, so by keeping all the cables along the side of the battens, well to the rear, it minimised the risk of someone drilling through a cable. I also took lots and lots of photos, showing all the cable and pipe runs, before the walls and ceilings were boarded out, and they have proved invaluable since.

No more than around 24 hours, and you can probably screw them out a bit sooner than that, as soon as the concrete has gone off enough to be stiff enough to not risk a burst.