What would a clean-sheet set of wiring regulations look like today?

Standardisation of wiring colours would be a useful step. Green/Yellow for ground/earth is almost there but the rest of the colours are scattered in function between the different countries. If I remove a light fitting in my Swiss apartment I may find a black wire and a yellow wire. The black is phase, the yellow is neutral. 

Redefining any of the current colours would merely increase the already huge legacy problem 

Whilst I agree that such systems are somewhat beyond the scope, I think the best way to avoid a zoo of incompatible equipment, with all the problems that causes for the householder, would be to specific a communications standard, if only a physical layer, to be used.

If we go with a DALI compatible physical layer, as an example, the wiring regs could reasonably impose a pair of thin data cores into cables in the same way they impose an earth conductor. It is a bit beyond the traditional view of BS7671, but if we can redesign wiring regulations (and their related regulations like the socket regs), we could impose such things if we wish.

I think smart controls using a single unified spec an excellent way to rationalise the current arrangements for lighting and the like that cause such issues in the field. If we have digital control of lighting just written into the specification, as an example, new installations never have to worry about the pain of two or three way switching and the confusion it can cause.

Such things are often referred to in the context of confusing DIYers, but during recent work in my house an apparent professional electrician managed to rewire the lighting to put a dead short between a switched live and a neutral, so the breaker immediately tripped (complete with a spark visible through the gaps in the casing!) whenever a certain switch was closed.

Just think of all the hours of fault chasing that could be eliminated if lighting was always "wire up like colours"? That could meaningfully ease the burden of the current electrician shortage and thus meaningfully advance the goal of all wiring regulations - effective, affordable and safe electrical installations for all.
We now live in the era of smart technology, I think we should fully embrace it to gain its benefits. If we don't specify smart controls we will have serious problems with lock in, and the inevitable attempts to turn literally everything into an "app".

Also we could have the remotely switched sockets that the Americans always sing the praises of! Without the problems of their American implementation.

EIreland said:

I think all this reiterates that all new supplies should be at least two phase, and probably three phase since I doubt it costs much more.

This may be a bit Jack, but I am in the lifeboat (to combine both Army and RN turns of phrase).

I don't think that my 3-phase supply was significantly more expensive than single phase. OK, the service cable and service head would have cost a little more, and of course, there is a little bit of extra labour in joining four rather than two conductors. However, getting to site and digging the hole in the road is the same.

EIreland said:

My understanding is that the National Grid DNO operation (is that Western Power Distribution?) has started replacing 100A cutout fuses with 80A fuses

We have coped on a 60 A fuse for years and, frankly, if you are above that level for a significant amount of time, your leccy bill is going to be eye-watering.

Don't think that a 3-phase supply at home is going to get you 69 kW on demand. My contract is for 30 kW ADMD even though the fuses are 100 A. Similarly, I understand that the standard contract is for 18 kW (i.e. 80 A) for single-phase domestic.

HI,

I think the solution to this is to make the smart meter the protective device for long term overload, unless we are going to add another piece of equipment to everyone's meter cupboard.  The meter already has a contactor and the necessary smarts to detect overload, the only thing it doesn't know at the moment is the supply rating.  There are only two wrinkles to that - (a) the contactor will probably need to be uprated for that application and (b) smart meter software will need to be developed to a recognised integrity standard if it is to be used for a safety application.

That approach, coupled with the use of the smart meter as a hub for the provision of total demand data and demand reduction requests (either from the electricity supplier or the DNO) to large loads could allow some sophisticated tariffs and useful demand control, far better than the existing attempts embodied in the EVSE regulations.

As this is a discussion about the wiring regulations, the interesting question is whether and how, if the above doesn't happen (and I'm not holding out any hope that is does in the near term) the regulations will require a level of load control more sophisticated than a CT connected to the car charger.

Chris Pearson said:

We have coped on a 60 A fuse for years and, frankly, if you are above that level for a significant amount of time, your leccy bill is going to be eye-watering.

I'm sure that 60A was plenty when my house was built in 1968. But now it's starting to look a bit weedy.

If I plug the car in to charge (7.2kW*) and take a shower (7.5kW), then that's the entire supply capacity for the house.

I'd like to install an A2A heat pump one day, in place of the gas central heating. But that's another large load that could be running for hours on end. Plus I would have to use the 3kW immersion heater overnight for the hot water.

Realistically, any new house should be wired 3 phase, and maybe an upgrade programme for older houses that need it.

*Actually my EVSE is currently set to 5kW, for reasons.

Simon Barker said:

I'd like to install an A2A heat pump one day, in place of the gas central heating.

In which case you'd have the option of using the HP for (pressurised) hot water too - so no need for the instantaneous electric shower - so that's 32A freed up (before diversity).

In France, I gather, instantaneous electric showers as we know them are practically unheard of (because of their 32A or 40A single phase supply limitation) - their way of doing an electric shower is an immersion heater in a pressurised cylinder run off-peak - generally more expensive to install, but better flow, cheaper to run and fits naturally between larger daytime loads like cooking.

   - Andy.

Simon Barker said:

If I plug the car in to charge (7.2kW*) and take a shower (7.5kW), then that's the entire supply capacity for the house.

Surely, you can arrange your routine so that you charge the car and shower at different times. ;-)

I agree that load control has an important part to play, but I think one of the most important advantages of electricity is that the householder can use lots at once if they need to. I'd be very worried about diluting that advantage. After all, decarbonisation will require people to use a great deal more electricity than they have before, even if the heat pump rollout delivers everything that is promised.

We could quite easily end up in a situation where we have a 32A car charger and a ~20+A heat pump running continuously for hours. Especially if the 7kW charger load swaps between two vehicles in sequence. That wouldn't leave much for things like a cooker on a 60A or even a 100A system.

I would think that any future supplies should be based on 2 or 3x100amp supplies.

We do have an example of a highly electrified society, in Quebec. Now obviously their heating loads are way more extreme than in the UK, especially in a heat pump future, but they also don't have huge penetration of electric cars there. 

Typical electrical installs there are 240/120V split phase systems with 200A on each side. That's something equivalent to a 200A supply in the UK.

I don't think the terminations or the cost of the cable is really a major driver on supply cables, so I see little reason not to provide people with a three phase supply. I think we should be aiming for major growth in electricity use as it displaces all other fuel sources, after all, using more is a good way to make electricity cheaper by amortising fixed costs - doubling the rating of a distribution system doesn't double its capital  or operating cost after all.

Do French Linky type meters simply open the contactor instantaneously if the current flow goes over a set limit, or are they sophisticated enough to run a current history model?

EIreland said:

Do French Linky type meters simply open the contactor instantaneously if the current flow goes over a set limit, or are they sophisticated enough to run a current history model?

The traditional French approach to was for the supplier (EdF) to supply a kind of adjustable 500mA RCBO (like this: www.manomano.co.uk/.../itron-400020-differential-circuit-breaker-edf-2p-60a-500ma-selective-sdb-ii-500-60a-s-6422703 ) at the demarkation point - the 500mA RCD provides a starting point for ADS (as their supplies are all TT) and the little window shows the current setting - usually 30, 45 or 60A I think. I believe the current setting is sealed and if tripped it's a call to the supplier to get it reset (and repeat offenders are 'offered' a higher (more expensive) option. I presume the underlying mechanism is similar to the thermal element of an MCB, but that is a guess.

I don't know if they're sticking with the same approach with smart meters.

   - Andy.

EIreland said:

We do have an example of a highly electrified society, in Quebec. Now obviously their heating loads are way more extreme than in the UK, especially in a heat pump future, but they also don't have huge penetration of electric cars there. 

Typical electrical installs there are 240/120V split phase systems with 200A on each side. That's something equivalent to a 200A supply in the UK.

The economics are very different though, Quebec has what are to British eyes, almost unbelievably cheap domestic electricity rates of around 7 CAD cents per kWh, that's about 3.5p/kWh. After the first 40kWh per day, that rate rises to the giddy heights of 11 cents, so 5.5p/kWh !

At those kind of prices, simple resistive heaters and storage heaters are a competitive form of heating.

With British domestic electricity unit rates around 5X that, the cost aspect will act to constrain demand in Britain.

Well yes, Quebec electricity rates are so low as to almost justify the old claim of electricity "too cheap to meter".

There is actually a cheaper tariff than the one you suggest if you have an auxiliary heat source to use in deep winter (defined as when the thermostat in your meter cabinet reads less than -12C!). That gives you 5.3 canadian cents per unit the rest of the time,  albeit with the cost of 30 canadian cents below -12C.
There is a reason  that Quebec has as many private pools per capita as California.

Whilst rates are in Ontario are much greater, they too have a time of use tariff with an overnight rate of only 3.9 canadian cents, or 2.1 pence per unit. That is a heavily nuclear dominated system, with their regular rates about 12 cents canadian per unit.

Off peak electricity will be extremely cheap in a renewable dominated system,although the times when it is used may be unpredictable.

If significant nuclear capacity is built it will be almost free. I believe before electricity market liberalisation, the "Option TEMPO" six-rate time of use tariff provided by EDF varied from 50 eurocents per unit to only 3.

We won't reach canadian levels, but the average electric car charging load will be something like 10GW, based on existing car mileage. If car mileage goes up due to low marginal costs, it will be more. We should expect radically more use than before, and this will probably drive down unit costs by amortising fixed costs.

EDIT: The cost delta per unit between my energy providers 'Economy 5' EV tariff and gas is getting much smaller than it has been in the past....

Well yes, Quebec electricity rates are so low as to almost justify the old claim of electricity "too cheap to meter".

There is actually a cheaper tariff than the one you suggest if you have an auxiliary heat source to use in deep winter (defined as when the thermostat in your meter cabinet reads less than -12C!). That gives you 5.3 canadian cents per unit the rest of the time,  albeit with the cost of 30 canadian cents below -12C.
There is a reason  that Quebec has as many private pools per capita as California.

Whilst rates are in Ontario are much greater, they too have a time of use tariff with an overnight rate of only 3.9 canadian cents, or 2.1 pence per unit. That is a heavily nuclear dominated system, with their regular rates about 12 cents canadian per unit.

Off peak electricity will be extremely cheap in a renewable dominated system,although the times when it is used may be unpredictable.

If significant nuclear capacity is built it will be almost free. I believe before electricity market liberalisation, the "Option TEMPO" six-rate time of use tariff provided by EDF varied from 50 eurocents per unit to only 3.

We won't reach canadian levels, but the average electric car charging load will be something like 10GW, based on existing car mileage. If car mileage goes up due to low marginal costs, it will be more. We should expect radically more use than before, and this will probably drive down unit costs by amortising fixed costs.

EDIT: The cost delta per unit between my energy providers 'Economy 5' EV tariff and gas is getting much smaller than it has been in the past....