Posts by Martin an gof

Re: It's all about cities AKA a systems problem

probably by concentrating on making public transport much better

Having just returned from a few days in the capital, while I'm sure things could probably be improved (though major re-routing of underground or overground lines simply ain't gonna happen), public transport in London is already vastly better than anywhere else I know in the UK. I will never forget the first time I took my then 17 year-old on the underground. We needed to travel from Paddington to Tower Hill. Firstly he was amazed with the workings of Oyster cards (no faffing about buying paper tickets), then we saw a Circle Line train pull out, so he started looking for a bench to sit on. After all, around here you are lucky if buses or trains come along more often than every 20 minutes. Of course there were no benches, but before he had explored even half the length of the platform, another train pulled in. "Gobsmacked" is putting it lightly.

Spend even half the amount of money London gets for its transport infrastructure thinly across the whole of the rest of the UK and marvellous things could be done. Same offspring returned from work today to a station about a 3 mile drive from our home. Sensible planning in the 1970s means that there is a bus station right outside, but the bus he normally uses, which gets to within a quarter of a mile of our house, had just left and another wasn't due for at least 30 minutes. Instead he was surprised to find the "community" bus - which only runs three times a day - waiting. This bus stops within 200m of our house, but I believe it took him over 45 minutes to get there, so circuitous is its route. Oh and, even subsidised it cost him about the same to travel that distance as it costs to travel on the Underground from Zone 3 to Zone 1 off-peak, say 9 miles from Ealing to Piccadilly Circus. As for the bus, a flat rate of £1.65 off peak? As far as I'm aware there is nowhere else in the country which can match that.

M.

Re: The Tory Government to the plebs

Weekending ran for a lot longer than Thatcher did, had a great theme tune in the 1980s and was edited by (among many others) Lissa Evans who is still in the business - worked on Father Ted, for example, and Have I got News for You. I've a couple of episodes on cassette tape knocking around somewhere. No idea why, must have a listen and find out if it was just my younger self recording it because I could, or if they were actually important episodes.

A successor in some ways I believe, to TW3 (That Was The Week That Was) and a forerunner of Dead Ringers among others.

M.

Re: I still don't understand

pretty much any home with over two bedrooms has enough roof to power that house

Speaking for the UK, our 2-bed or even 3-bed houses would often struggle to find enough suitable roof to provide enough power for the whole house, especially in an all-electric future. At between 50°N (Cornwall) and 60°N (North Scotland) and with often inclement weather (ranging from 1,100 to 1,750 hours of sunshine a year) it's harder to maximise output, and with a typical new-build 2-storey, 2-bed house in the UK having a footprint of perhaps 35m² or less*, and situated on a development higgledy-piggledy style so that most properties do not have roof oriented anywhere near South, you might need quite a lot of panel to average the 10kWh per day typically consumed in a 2-person gas-connected house, much less the 25kWh per day you'd use in an all-electric situation (same source, my assumption that 33kWh of gas is replaced with 15kWh of electricity by using a heat pump).

That isn't to say that you shouldn't consider solar PV. "Every little helps" as they say, but your sweeping statement isn't necessarily true worldwide.

As for a ground source heat pump, typical house plots in the UK are nowhere near large enough (see the Taylor Wimpey link above again - that house has a total plot of perhaps 100m² including the bit on which the house sits) for either a horizontal pipe or a vertical trench pipe**. Boreholes are prohibitively expensive and in large parts of the populated country are impractical due either to underground infrastructure (gas, water, electricity, sewers, London Underground, nuclear bunkers and the like), abandoned or still-active underground workings (coal mines, ore mines) or complex ground conditions. Our own house, for example, sits on top of several coal seams, some of which may have been worked many years ago (but no-one knows for sure), a couple of mineral seams and a geological fault line. A borehole would be a risky investment.

Oh, and in terms of new-build, no developer is willingly going to fit £10,000 of PV and £15,000 of ASHP or £30,000 of GSHP if his competitors are fitting £2,500 worth of gas boiler. Either his houses will be correspondingly more expensive off-plan (and it's that headline figure which grabs the attention, not the ongoing running costs) or his profit margin is vastly reduced.

There are some PV technologies in development which are much less expensive than existing technologies, but they are also much less efficient. There comes a point, however, where something becomes cheap enough to be almost an "impulse" purchase, and you can compensate for lower output by installing more.

M.

*because I know that link will expire at some point, it's to a 2-bed semi-detached property by Taylor Wimpey which has a gross floor area of 771ft², which is around 72m² which implies a footprint of around 36m²

**one company I found estimates that for a horizontal GSHP pipe layout, a maximum figure of 12m² per 1m² of floorplan should be used - let's be generous and say that for a modern, well-insulated house you could get away with 4m² per 1m², that's still four times as much total plot as the house in question actually has, and that's assuming you're happy to run the pipe under the house itself

Re: And we also want EV's?

Can confirm your suspicions

Difficult to follow the threading, but do you mean me?

It is well known that the "last mile" has problems in many parts of the country, and if National Grid says they can cope, they probably can. The infrastructure inherited by and installed by DNOs was largely designed in the days when you could budget 2 or 3kW per house and be safe at that, and that's what the biogas operation I mentioned is dealing with. They are still - partly - a farm, but the overhead lines which feed the farm and the substation to which they are attached cannot cope with (much) more than the 1MW they currently generate.

Quite why installations made in the last 10 years or so should be underpowered, I dunno. Western Power has already carried out trials of domestic three phase connections (not the link I was looking for, but gives an idea). An overview of the system and some of its limitations can be found here (PDF) in a very readable guide to connections.

Anecdotally, whenever work needs to be carried out on the single pole-mounted transformer which powers our entire hamlet (maybe 70 or 80 houses) WPD usually bring along a 100kW generator, which works fine during the day but usually conks out around tea time. Gas came late to the village and many houses still rely on electricity for heating, hot water and (particularly) cooking. Last time they came they couldn't even get the thing started at breakfast time and had to send out for a bigger unit. My point? Current "rule of thumb" estimates of use may not be valid for much longer.

M.

Re: And we also want EV's?

Don't forget that there are two entities involved here - National Grid is responsible for the "big" stuff - the 400kV, 275kV, interconnects and such. I suspect that the capacity problems here are down to the Distribution Network Operator, of which there are several across the UK with the one responsible for the Heathrow, Ealing etc. area being (I believe) UK Power Networks - it looks as if their boundary finishes at the M25 with Scottish & Southern westward of that.

DNOs are responsible for connections to businesses and homes and most of the substations and transformers you see locally, so while National Grid may well be able to shovel electrons around the country perfectly sufficiently, if the local transformer is undersized for the demand, or the underground 11kV and 415V cables need uprating, it's not really their problem.

The thing works the other way too, I recently met a very interesting local enterprise which takes the council's compostable waste, turns it into biogas and generates 2x 500kW (IIRC) from that, day and night. They are connected to their local DNO and cannot expand because the DNO's local network couldn't cope. In order to expand they would need to run a cable to the local National Grid substation, which is prohibitively expensive in their current plans. An alternative they are considering is to feed some excess gas into the gas network, which is apparently slightly closer to hand and has a bit of spare capacity.

M.

Re: Years ago....

The paper ones aren't cheap either!

But if you buy the paper one, you get the digital one as well these days, unless I've mis-read something.

Paper's always best, except for those two-sided tablecloths they do these days. Bring back the pocket-friendly Pathfinder I say :-)

M.

SD cards are so simple (they are basically just a NAND chip on a PCB)

While I know that was basically the case with xD cards, Smart Media and certain other early card formats, I'm pretty certain it's not the case with SD - all SD cards have a controller onboard which translates between the NAND and the interface, which is how larger sizes have been more easily accommodated than with the other formats:

Wikipedia: memory card formats technical details

M.

I have a dozen or so first-gen Sony-built Pis at work, in constant (near 24/7) use playing videos since 2012. They were pretty awful at trashing cards in the early days, but the first batch of cards I bought (or rather, had bought for me) were what could be found at Tesco and Sainsbury's because of course putting the display together was a bit of a rush job.

It seemed mostly down to being powered-down mid-write, and often the cards could be recovered with fsck or whatever, and if not they could usually be reformatted even if that meant using the SD Card Association's official formatting tool. Powerdown during boot was almost guaranteed to trash the card and often in such circumstances the card was unrecoverable afterwards.

However, updates to the Pi's operating system have largely mitigated those problems, as has the use of genuine Sandisk, Samsung or Transcend cards, and I very rarely get a problem these days. I've subsequently bought quite a lot of Pi2, Pi3 and a couple of Pi4 and can honestly say that in the - let's call it nine years - since the first generation stopped mucking about I've had only two or three cards "just die" for no apparent reason.

As regards the problem in the smartphone, my suspicion would lie fair and square with Android I'm afraid. There is nothing intrinsic about a (good) SD card which makes it more fragile than any other removable storage medium as far as I can tell, I have SD cards in smartphones and non-smartphones, stills cameras, video recorders and mp3 players at home that have lasted years without issue.

M.

Re: I just installed it

I already run a gazillion* Pis around this place, but from the article I don't think a Pi has the grunt to be able to run the software (leaving aside the fact that it's Windows-only at the moment) which does the image analysis required to locate a user's hand in space and determine if they are making a "click" or "zoom" or "wipe" or whatever gesture...

M.

*rough approximation

Re: I just installed it

I have a potential use-case for it, but placement of a webcam is going to be awkward - it'll either be off to one side or about 8ft away from the user above a projected image. I suppose I could look for a webcam with a zoom lens.

Your experience is that it doesn't like being too close, but how about far away?

M.

Re: Bloody batteries and solar panels

cable under my road is rated for 400 Amps. One electric shower is 40A, one EV charger is 40A, and one heat pump is 40A. But my street has 30 houses, so the underground cable regularly overheats and fails

If it does so then that's something your local company needs to sort. It's not quite as bad as it sounds though - you make it sound as if each house needs 120A constantly and there's only 400A to go around.

Firstly, that 400A cable (assuming you are correct on that) is three-phase, and each house only takes one, so that's 10 houses (roughly), not 30. This means a fairly normal 40A capacity per house, though some installations can be higher. The calculation / risk is that no-one will be using all their allocation all the time, so it doesn't matter if they take more than 40A some of the time, and it's likely that the houses have 80A main fuses, possibly 60A. Some modern installations will have 100A fuses.

Secondly, the electric shower is a very short-term load and won't be exactly 40A. Common shower powers in the UK are 7.5kW, 8.5kW (both likely fused at 40A but drawing approx 32A and 37A at 230V) and 9.5kW and 10.5kW which will be fused at 50A and draw approximately 41A and 46A. Certainly for the 50A devices the installing electrician is required to ensure that the supply is capable and to do so a "maximum demand and diversity" calculation will have been made.

Shower loads are resistive and so very voltage-dependent - as the voltage drops, so will the power produced and the current draw.

The car charger, I don't really know as I don't have one. Those I have seen are 7kW, fused at 32A, not 40A and even if the thing is a typical switch-mode PSU and tries to draw more current as the voltage drops, it won't take much before the MCB pops - MCBs are not voltage-dependent. If the problem is structural outside your house then it will affect everyone else and such a condition is also likely to pop the fuse at the transformer. If this isn't happening - which it seems not to be if the cable is catching fire - then as I said, something bigger is wrong. Around here I would expect Western Power Distribution to be on the case fairly rapidly as they have been for other issues.

The heat pump has already been discussed by others, but I can see how a large installation might need a 10kW device - especially if you include the resistive heaters usually fitted to the hot water storage - but a note for those people currently running 35kW or 40kW "combi" boilers, heat pumps do not attempt to replace those; much less than that is needed by the space heating in most houses. A combi boiler needs that amount of power in order to produce decent quantities of hot water, "instantaneously". Heat pumps heat and store hot water in a cylinder, meaning less instant heat power is required, but it's needed over a longer period.

However none of these things is a constant load, all day, every day. Just because you take a ten-minute shower at 7am, it doesn't mean that all 9 of your same-phase neighbours are doing the same. This is the "diversity" I mentioned. On a smaller scale it's how you can connect an electric cooker to a 32A (7kW) circuit when it probably has 3kW + 2kW + 2Kw +1kW of hob, 2kW of oven, maybe 2kW of grill and a 13A socket outlet at the switch - if you add all that up, it comes to a potential draw of 15kW which is 65A! Thermostatic controls and the way the oven is used mean this never happens in practice so the diversity calculation for an oven (from memory because I don't have the book to hand) is something like:

10A + 30% of remaining load + 5A if a socket is fitted

Using that on the above example (52A cooker + 13A socket) gives a diversified load of 10A + 30% of 42A + 5A = 27.6A, well within the 32A allowed.

M.

"Winchester"? Do you mean WD?

Anyway, what I have often done at home is to purchase from different suppliers. It's unlikely CPC and eBuyer (just as examples) will have discs from the same batch, and it means that other than a couple of days difference in the delivery times, I get everything at the same time. I also use RAID6 (or equivalent) so the system can survive two failed discs, "just in case". The main downside is the reduction in the amount of storage available.

M.

Re: magnificent

Bemny Hill - don't go there, though the man himself is in the original Italian Job, which isn't half bad.

Fawlty Towers, try Father Ted or, of course The IT Crowd, both by Graham Linehan.

Red Dwarf - Chris Barrie went on to do The Brittas Empire which isn't dreadful.

Anything with Alan Partridge.

Anything by Armando Ianucci - The Thick of It is probably easier to find than The Day Today.

In a slightly similar vein, Twenty Twelve and, of course, W1A.

Let me.know how you get on :-)

M.

The thing that people have (very recently) started calling a "thermal battery" was formerly known as a "thermal store". Instead of using tubes or plates to heat water in a normal hot water cylinder, from which the water is used directly in the taps - meaning you have to limit it to 60C or so to avoid scald risks - a cylinder is heated to anything up to 95C, meaning more energy is stored in the same volume of water. Water for taps is taken out either via a mixing/blending valve or via a heat exchanger.

We already have such a cylinder. It has a capacity of 370l and 100mm of foam insulation, and although I've set an upper limit when the solar is running of (without going to check) 85C, I've yet to see the thing much over 65C except when I let the boiler take it there, and I've never seen the solar system shut down because of over temperature.

Our cylinder has a coil for solar at the bottom, a coil for the boiler higher up, two immersion heaters (at about ½ and ¾ height) and a direct connection for the future use of (say) a log burner back boiler. It has a third coil to take heat out for the radiators & underfloor heating. The water in the cylinder is not used directly in the taps or in the heating circuits and because it is not pressurised (mains pressure cylinders have to be installed by a registered plumber whereas ours has a header tank so is at atmospheric pressure only) it was a fairly easy DIY installation.

The mains cold water only goes through the heat exchanger, which is set to 50C (it's an active system with a variable-speed pump and theoretically capable of transferring 70kW) which reduces the risk of deposits from "hard" water, not that that's an issue around here as our water is very "soft".

But still, if a shower uses (say) 5l/min of hot water and six people each take a ten minute shower (which is optimistic in this house!), that's 300l of hot water which equates to something like 230l of the water in the cylinder (300l × 50C ÷ 65C), if the cylinder has reached 65C throughout.

Or to put it another way, 300l of water has been raised from 10C (ish) to 50C, which takes about 38kWh of energy (300l × 4.186J/l/C × 30C ÷ 1hr - I think that's right), so if only 15kWh has come from the boiler, 22kWh must have come from the tubes (which are rated as 3.2kWp), which isn't bad going really.

Sunny Friday's gas consumption was about 17½kWh, rainy Sunday (also cooked Sunday lunch) was 43kWh, just as an example.

Our cylinder came from these people by the way, bespoke to fit the space we had. Very helpful and not as expensive as you might think.

M.

Our remote display - smart meters were a non-optional replacement for dumb meters when we had the incoming electricity and gas moved as part of our rebuild - went for a couple of months without being able to show historic gas records - it just suddenly stopped one day. It would show "today's" consumption right up until about 2350 or so, then it would show zero. And paging back through previous days would show zero for all of them. The historic total (gas + elec) appeared to be correct - it was a different number to the electric-only historic detail - but that, coupled with the fact that all historic readings seemed to go haywire between 2350 and about 0100, meant I couldn't rely on it at all.

We had a (planned) power cut, and since then it's been ok with historic data, though it still shows odd readings between 2350ish and 0100.

Mum and dad would benefit from a smart meter as their current one is buried in the back of the cupboard where they keep the cat food and they report usage by phone monthly, but no mobile signal so pretty pointless really - it would be even more difficult to read as the remote display (if it worked at all) doesn't seem to show the number on the front of the meter, and while their existing meter, though awkward to access, has big high-contrast digits, easy to read with a torch, the "meter" parts of smart meters seem to have difficult-to-see-even-in-daylight reflective LCD displays with multiple button pushes required to get the reading you need.

Leave them as they are, I say.

M.

The total power consumption is single digits of watts, a pittance against running a fridge

I think this is something that cannot be stressed enough. An elderly relative recently asked me - scared about the impact of the last price rise on their electricity bill - whether turning off the "flashing lights behind the telly" would be worthwhile. Given that the flashing lights are the WiFi access point, and they rely on an iPad for certain communications, no. Absolutely not.

People are being bullied into unplugging phone chargers, leaning down behind tellies to switch them off at the plug, switching microwave ovens off at the wall etc., when such use - particularly with modern appliances which use so little power in "standby" that a typical domestic plug-in meter cannot measure it - is a teeny tiny fraction of use.

Heck, watching five minutes less telly in a day (even if the TV is put in standby) saves enough power to run the WiFi access point for an hour or more, and my relative has a habit of leaving the telly on "teletext" with the cricket score updating in the background.

We have solar hot water tubes, but with a large family we are still using - at this time of year - somewhere around 15 - 20kWh of gas to heat water, mainly for baths and showers, each day. I am convinced I could reduce this use, because some of it is down to having to have enough hot water for those who take morning showers before the panels have warmed up. If the electronics I add uses 50W in total (likely a lot more than it will), it will use 1.2kWh over 24h. Given that the panels have a peak output of about 3.2kW - let's call it 2.4kW typically - if the system can allow just 30 minutes of additional solar heating a day, I've broken even.

Actually, come to think of it probably not in cash terms, as the 1.2kWh for the electronics is electricity, while the boiler runs on gas which is about a quarter the price, so it'd have to be two hours. Hmmm... not quite so easy, but not at all impossible in the summer I reckon.

M.

Two things - balancing is absolutely a great idea, but whether or not it is (properly) possible really depends on what kind of cowboy fitted the rads in the first place.

Secondly, my experience with TRVs - the traditional wax-capsule, sit on the flow pipe sort - doesn't fill me with confidence, and they actually make the job of balancing - even when they are working 'properly' and not stuck open or measuring the heat of the warmest part of the room (surely the very worst place to put a 'thermostat' is up against a radiator!) - much harder.

I'm in the process of building a heating control system similar to the OP's, using Arduinos, but I am fortunate that my starting point is a new, well-insulated house with a heating system installed by me. Radiators and underfloor heating all runs from manifolds which means that each one has a separate valve in a central location, so I can control eight radiators from a single Arduino. The manifolds have flow-control valves (what is termed a 'lockshield' on a normal radiator and is used to balance the system by controlling the flow through each radiafor) which actually has a flow rate indicating function so you can see the results of tweaking, and one of the best innovations, all the pumps are electronically controlled and vary their speed according to demand. In theory then, each radiator gets the flow it needs both when all radiators are 'calling' and when only one is on.

M.

Re: Ego Musk

It's great that the list is expanding - and certainly something I'll consider when eventually I have to go electric - but I note that none of the cars mentioned at that link (thanks for that, by the way, not a site I'd previously come across) has "real world" range figures - particularly for towing, where they are all estimated at 50% of their predicted non-towing range, which means some of them have towing ranges below 100 miles - and presumably even less if you are at motorway speeds. That is quite some tedious holiday.

Oh, and the cost!

By the way, I do like the "EV Database" method of comparing charge rates, as "miles per hour"!

M.

Re: Ego Musk

If you choose your platform correctly, I don't see why re-using an existing platform is a major problem. Nissan adapted the long wheelbase version of the Renault Clio / Dacia Sandero platform for the Leaf, naming it the "EV" platform according to Wikipedia, and this was back in 2009. Siting the battery is an interesting problem, but Nissan seems to have found room under the cabin without impacting on legroom too much. I assume the additional weight and different weight distribution means the suspension needs a bit of thought, but apart from that, as a front wheel drive car has the entire "drivechain" packaged under the bonnet, in much the same way as you can fit several sizes of internal combustion engine into a particular model of car it can't be rocket surgery to "drop in" an electric motor and drive.

As a benefit you don't have to spend time re-developing all the in-cabin stuff, and you are probably a long way down the road to safety certification.

The only reason Tesla hasn't developed their EVs from an existing ICE platform is that they had no ICE platform from which to develop!

Of course, if you're going to use in-wheel motors (there must be a reason why none of the mass-market cars (as far as I'm aware) use in-wheel motors) or chassis-mounted motors near each wheel then there may be other considerations which might mean starting from scratch brings more benefits.

M.

Re: Ego Musk

that can do some light towing

That's an interesting requirement. As far as I'm aware - and I'll admit I haven't looked for a while - the Tesla is the only pure EV which even has a towing rating. Last time I looked, every single other one said "no towing". Then there's the range to consider. By all accounts, just bunging some bikes on the roof of an EV can reduce range by 25% or more, and hooking a small caravan up can have a 50% impact. I can't find it now, but I'm sure I read someone doing a review of one of the Teslas as a towing car saying that the torque was very welcome, but having only 100 miles range in a car which normally did 300 put a bit of a downer on weekends away.

M.

Re: Now Do an Article About the Top Ten Linux Apps

Ok, point taken. The one app I miss most on Linux is Xara Designer, I grew up with Draw on RiscOS, and Xara has evolved from Artworks on the same platform and has elements of Impression, which I used extensively for many years. Of course they really don't want to sell you a stand-alone app these days, but I can't get this online editing stuff, and I really resent having to boot into Windows just to run my favourite editor. I've never managed to get it working under Wine, and even in a VM it's ropey - laggy and with the "point of action" often not quite coinciding with the pointer!

I'm trying to get to grips with Inkscape, which seems to be theoretically almost as capable (for the things I need to do) but I'm not there yet.

M.

Re: Now Do an Article About the Top Ten Linux Apps

Because I do graphic design

Well, some people seem to manage.

It's not exactly click-and-go but David Revoy, whose portfolio I linked above, also has a comprehensive discussion of choosing Linux for his work platform.

M.

Re: My 1st attempt

Just curious - what sort of stuff goes under the category of "general stuff" as opposed to /home?

From my own point of view, at work the machine runs both Linux and Windows and I deal with some largeish media files in both. The partitioned boot device is SSD, one for booting, one for /home. There's a mirrored pair of smallish SSDs for video scratch files (only under Linux) and everything else sits on a "big" drive or two formatted NTFS so that both OSes can read them.

At home with multiple logins, the boot disc again a partitioned SSD, people store personal stuff in /home/<username> on the other partition, but space is limited so other files and shared files might be on a separate local disc where anyone can access them, or more commonly on a network share so that they can be accessed from any of the computers.

Advantages - easier to share files, easier to wipe root if a reinstallation is necessary without even thinking about data. OpenSuse no longer recommends separate partitions for root and home, but (again personally), I've found XFS to be a little faster when video editing than BTRFS so I still use separate partitions.

Or, in other words, "it sort of just happened that way. Seemed like a good idea at the time."

M.

Re: Not be happy ... to reinstall my OS from scratch every year or two

Have to agree with Liam here. The very idea of installing from scratch - particularly when not necessary - is ridiculous. I run openSUSE - both Leap and Tumbleweed - and have to say that the rolling release has improved hugely in the five or six years since I first tried it, when every second update would bork something, require a rollback, probably some kind of manual fix, or occasionally a re-install. I haven't actually re-installed Tumbleweed from scratch on either of the two machines which currently run it, since I built them some four years ago, but I tend to put off updating until I can spare half an hour to double-check it isn't going to do something silly, which usually means once a month or so and also means doing it from the command line - not exactly newbie-friendly.

Leap, slightly different in that a version upgrade (e.g. 15.2 to 15.3) is sometimes easier from the installation media, but I quite like the fact that in between versions it's relatively stable. Haven't had any borkage for... well... ages really. Can't remember the last time.

And I'm about to start my very first MacOS "reinstallation". A friend has a second-hand device which seems to have a few things on it that it shouldn't, so a factory reset is in order methinks...

Personally, I ran RiscOS as long as I possibly could (still do for some things) and then went straight to openSUSE somewhere around version 12.n (there was a Mac in the house too, not mine). Windows might have been simpler, but why make things simple when you can be different?

Did I just contradict myself?

M.

Re: Yellow? Perhaps in Britain.

Also, of course, in the "old days", UK earth cable was green while since the 1970s it's been green and yellow striped, so anyone mistaking a yellow cable - with printing on it as well - for an earth cable obviously needs some kind of "education"...

M.

Re: From the domestic side

Do you need any? I've got probably 90m of brown and blue left after building this house and quite possibly 50m+ of green&yellow. And that's after keeping a few m for future use.

I wired to the switches rather than the ceiling roses, so a: only one cable at the ceiling fitting (meaning those stupid fancy Italian-designed lights they seem to sell at B&Q are much easier to wire) and b: no "switch drop" which is where you usually have to sleeve the blue wire with brown as it becomes "switched live".

Two-way and three-way switching accomplished with 3&E cable to the very simple On Site Guide plan. 3&E is brown-black-grey which are all "live" colours these days so don't actually need sleeving, though sometimes it's a good idea to anyway.

On the downside, more wires in the backs of switches, but as this was a new build I just put a 25mm or 35mm box behind each switch instead of the 16mm commonly used in the past.

M.