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

It is an interesting thought experiment to consider how things might have been done differently if it wasn't for historical accident..

Years ago we weren't that fussed about ADS, just made sure that everything was solidly earthed. If we'd continued down that line we might now have c.p.c.s that a 4x the c.s.a. of the line conductors (so even during earth faults exposed parts remain below 50V) and probably concentric earth cables (perhaps think SWA but with copper armour strands) so far less reliance on RCDs etc.

Part of the idea behind ring circuits was instead of having multiple final circuits, you run the distribution circuit to the socket and have a final circuit for each appliance (far better discrimination, and better use of resources as copper is shared between different uses, making the best use of diversity). Ideal when you want lots of sockets for relatively low power appliances. Had we carried on in that vein, especially with the vast increase in the number of appliances, we might have ended up with domestics based on something more like flush dado bus-bar trunking with sockets just clipped in where ever they're wanted, no lighting circuits, just a FCU in each room for the lights, and possibly high demand appliances like cookers and showers tapping into the same system. So no CU as such, just one or two big fuses (maybe one per floor).

  - Andy.

TurboGen said:

Given that it was engineered during the WW2 period when central heating was very rare and the use of plug-in electric room heaters was common place, with it designed to allow use of heaters upto 3kW, it was always intended specifically to handle sustained loads. It appears something has changed over previous decades that we're now so concerned about using it for anything near its nameplate rating, for any length of time.

I entirely agree with the sentiment.

What strikes me is that the contact area between a plug pin and the slightly springy contacts in the socket-outlet  must be fairly slim, and brass rather than copper.

I am not sure how much people relied upon electric heaters. There was always coal. We had paraffin heaters for when it was not quite worth laying a fire. Next came gas fires, which bridged the gap quite nicely.

Nothing new about gas bayonet connectors. In one house, we had them by the coal fires, which allowed the use of gas pokers. So the hollow poker was poked (what else) into the coals and ignited. It was withdrawn when the coals got going. The existing supply was quite handy when my parents modernised and put gas fires in front of the fireplaces.

Does anybody use gas fires nowadays?

I agree - a continuously rated 13A socket and plug that did not need 'EV' stamped on it & that did not start cooking at considerably less would be good. 
.
The resistance of alloys for pins and terminals is not as good as copper, and its not helped when the 'U' springs get tired, especially with thermal cycling. I'm not sure  how much the hard metal (Nickel?) coating on the pins of Europlugs helps by reducing oxidation - we could copy that if it was worthwhile.

Some of the problem is the unavoidable heat generated in the fuse - if is going to melt reasonably rapidly at 20A, then it is going to be more than a bit warm to the touch at 13. Lower melting point fuse alloys are a partial step in that direction - in the days of hot wire fuses, there were different "30A" fuse wires that varied from tinned copper wire (melts ~1000C  ) to something that gave way at soldering temperatures (more like 200-250C I assume) that probably contained lead and would not meet modern green credentials.

I'd also be quite happy if behind the cooker we had an EN60309 /BS4343 or something custom that was a bit more compact -  would need repeal/ amendment of the plug and socket regs.
Mike

PS this seems familiar

Chris Pearson said:

I am not sure how much people relied upon electric heaters. There was always coal. We had paraffin heaters for when it was not quite worth laying a fire. Next came gas fires, which bridged the gap quite nicely.

Before my time, but i understand the dominant form of heating was still coal/coke fires in the main living room in most homes which are quite time consuming to light and manage, so electric fires were an increasingly popular form of quick and easy, top-up heating, for use during the shoulder months in spring/autumn, and in rooms like bedrooms.

There had also been financial changes taking place, the gradual move away from 1-part single rate tariffs (i.e. without standing charge) but with high running rate / unit rates originally designed for lighting loads, towards 2-part tariffs with a standing charge, but with lower running rate / unit rates which were closer to the marginal cost of power generation, which then made electricity more competitive for domestic power loads like cooking and room heating.

In the immediate post-WW2 period, the growth in electric heater ownership and usage had quite a significant impact on national power demand, to the point there were advertising campaigns to get people to limit their usage, avoid usage at peak times.

TurboGen said:

and in rooms like bedrooms

Softie!

The downside of EN 60309 'Commando' type sockets as I see them is there a veritable zoo of different configurations, based on rating and single/three phase. I'd worry we'd end up in the sort connector hell that they have in North America with the family of "NEMA" sockets.

Perhaps we could use IEC 62196 'Type 2' sockets instead?
They are rated for 3 phase 63A or single phase 70A, and the socket can use an inexpensive PWM circuit to communicate its actual rating to the appliance on the control pilot pins.

They are far from slim connectors, but I think they are generally comparable in dimensions to 3ph 16A and 1ph 32A connectors. Appliances would need a specialised flex (big neutral and phase 1 conductor), but if heating elements etc are wired as star configuration, it should be possible for them to operate either on single or three phase as the situation requires.

Then we could get away with only a single high power connector. The socket components are relatively inexpensive if you exclude the smart tech government currently insists is in EV chargers that we wouldn't need for an immersion heater! I doubt it would meaningfully increase costs over Commando sockets once every house contains several of them.

EIreland said:

The downside of EN 60309 'Commando' type sockets as I see them is there a veritable zoo of different configurations, based on rating and single/three phase.

But equally, there is a 'zoo' of applications. The voltage rating/phasing applications are colour-coded to BS EN IEC 60309-1, and the pin dimensions.layout, including  'major vs minor' keyway configurations for standard applications, are aligned using BS EN IEC 60309-2. I think that is a great approach, based on the earlier standards BS 4343 and IEC 309.

I agree that it is a great approach to the extremely diverse applications found in industry where we need a connector family that can meet any number of different requirements. And that it be able to do so without causing potentially very nasty accidents.

However, in the domestic setting, using the given example of someone buying a cooker and just being able to plug it in and go, I'd think we would want the maximum level of "plug and playness".

If we have a connector for the immersion heater, a connector for the cooker, a connector for a separate electric stove, and a connector for an air conditioning unit, all of which might be different designs (especially if three phase becomes more prevalent domestically) we might dilute the opportunities for true "plug and play".

We might end up in a situation where the new cooker comes with a connector fitted to a chunky flex, but it doesn't matter because you have to get an electrician to change the wall socket for you regardless.

Yes, the IEC60309 and IEC62196 are physically large, tough / impact resistant plugs and typically have the cable entry inline / parallel with the pins. Whereas for domestic applications, the requirements are somewhat different - impact and water resistance requirements are lower but the size and space is more critical, so cable entry at 90 degrees to the pins, to make the plug depth lower and the cable to remain close to the plug/wall, to reduce the overall depth required for a plug inserted into a socket, and the stand-off of any appliance in front of the plug.

My starting point for a higher current domestic plug/socket, would be the 30A version of BS 546.

But I wonder if we could learn from the Australians and their ingenious design of backwards compatible plug/sockets (AS/NZS 3112) which allow lower current plugs to be used in their higher current rated sockets. Could we engineer a 20A and/or 32A socket, using that same approach of wider socket pin entry and wider pins within the same overall parameters to retain backwards compatibility with existing BS1363 plugs?

Potentially, could we have 32A sockets, which could be used with higher current appliances while retaining full compatibility with existing BS1363 plugs? The Australians have achieved this, I wonder if it is possible within the envelop of a BS1363 plug/socket.

EIreland said:

However, in the domestic setting, using the given example of someone buying a cooker and just being able to plug it in and go, I'd think we would want the maximum level of "plug and playness".

BS EN IEC 60309-2 covers that, making things pretty much 'plug and play' ... there is only one pin configuration and keyway option for a standard socket-outlet (in each current rating) for a 5-wire 230/400 V 50 Hz system, and similarly one in each current rating for a single-phase socket-outlet ... there is another keyway option for 60 Hz. Sometimes industrial applications might use the non-standard 60 Hz keyway option for a particular machine, which means it's not available for 'general use' but then that's what 'not plug-and-play' is intended to be.

I'm not sure what the issue is? We don't want to be able to plug a 110 V (55-0-55) RLV single-phase plug into a 230 V socket-outlet do we?

Similarly, I can see that the designer (not the user) should have some modicum of control over which phase the user connects a single-phase 230 V product to in a 230/400 V system.

The 'standard' sockets for normal UK 50 Hz supplies are:

• 230 V single phase 50 Hz, colour-coded blue, keyway position 6h with the earth pin/tube at the 6h position
• 400 V three-phase 3-wire 50 Hz, colour-coded red, keyway position 6h  with the earth pin/tube at the 6h position
• 400 V three-phase 4-wire (i.e. TPN), colour-coded red, keyway position 6h with the earth pin/tube at the 6h position

A 400 Hz three-phase 4-wire device can be connected via a three-phase 5-wire plug, of course, but we don't want the 4-wire socket-outlet to be directly compatible with a 5-wire plug, because if the neutral is needed, it's actually a serious fire hazard to not connect it.

I think that's about as plug-and-play as it gets !

Whilst there is only one keyway position for any particular configuration, the problem is there are numerous configurations that could reasonably be adopted in a household situation. Many supplies could supply many of the loads, but since all sockets and plugs are only compatible with the exactly matching socket and plug, there may be little "plug and play" in practice.

A 230V 63A socket-outlet can connect solely to a 230V 63A plug. It cannot supply a 32A or 16A plug fitted load without an extension lead even though it would be entirely safe to connect a 16A load to a 32A or 63A supply, just as it is safe to plug a 2.5A europlug into a 16A Schuko socket.

Likewise, a 400V 32A 5-wire socket cannot be used to directly supply a 16A or 32A 230V single phase load despite, again, it being entirely safe for such a connection to be made. It cannot supply a 400V 2P+E, 3P+E or 2P+N+E plug at any current despite it being safe for it to do so at 16/32A.

We could quite easily end up in a situation where similar appliances might have different connectors, requiring repeated modifications to sockets because the socket must always precisely match the appliance. Unless of course we force standardisation to a very large current capacity socket (for example a 63A single phase or 32A three phase) on every outlet, with the associated size issues. 

That also doesn't get around the issue of connecting single phase loads to three phase supplies, which is a situation which might be desirable in a household setting. As far as I know we'd have to deviate from the published IEC 60309 (EDIT: not 30609 sorry!) standard to allow for some sort of universal single/three phase socket/plug combination.

As an example, imagine a kitchen fitted with a 63A 230V socket for the cooker. You buy a new cooker that comes only a 32A plug as it only requires 32A. You now require a bulky and annoying extension lead (which may not fit in the space!) or you require an electrician to replace your 63A socket with a 32A one.

Using a IEC62196 connector would provide a single socket/plug combination that could meet all foreseeable loads (70/80A at single phase is 16-18kVA, 63A at three phase is 43kVA!) and which supports both single phase and three phase operation. If three phase capable appliances have a DPDT contactor allowing loads to be switched between phase 2/3 and phase 1, they can operate from either as required. A single phase only load can just connect to phase 1 and ignore the others.

The socket outlet would be able to signal its actual current rating to the appliance which could throw an error if connected to a supply it cannot operate on, or simply operate at reduced power (for example a cooker not allowing all rings to be on at once).

The designer would have the ability to distribute single phase loads to the desired phase by connecting that phase in the L1 position on the socket, which is the phase used in single phase mode. 

Whilst there is only one keyway position for any particular configuration, the problem is there are numerous configurations that could reasonably be adopted in a household situation. Many supplies could supply many of the loads, but since all sockets and plugs are only compatible with the exactly matching socket and plug, there may be little "plug and play" in practice.

A 230V 63A socket-outlet can connect solely to a 230V 63A plug. It cannot supply a 32A or 16A plug fitted load without an extension lead even though it would be entirely safe to connect a 16A load to a 32A or 63A supply, just as it is safe to plug a 2.5A europlug into a 16A Schuko socket.

Likewise, a 400V 32A 5-wire socket cannot be used to directly supply a 16A or 32A 230V single phase load despite, again, it being entirely safe for such a connection to be made. It cannot supply a 400V 2P+E, 3P+E or 2P+N+E plug at any current despite it being safe for it to do so at 16/32A.

We could quite easily end up in a situation where similar appliances might have different connectors, requiring repeated modifications to sockets because the socket must always precisely match the appliance. Unless of course we force standardisation to a very large current capacity socket (for example a 63A single phase or 32A three phase) on every outlet, with the associated size issues. 

That also doesn't get around the issue of connecting single phase loads to three phase supplies, which is a situation which might be desirable in a household setting. As far as I know we'd have to deviate from the published IEC 60309 (EDIT: not 30609 sorry!) standard to allow for some sort of universal single/three phase socket/plug combination.

As an example, imagine a kitchen fitted with a 63A 230V socket for the cooker. You buy a new cooker that comes only a 32A plug as it only requires 32A. You now require a bulky and annoying extension lead (which may not fit in the space!) or you require an electrician to replace your 63A socket with a 32A one.

Using a IEC62196 connector would provide a single socket/plug combination that could meet all foreseeable loads (70/80A at single phase is 16-18kVA, 63A at three phase is 43kVA!) and which supports both single phase and three phase operation. If three phase capable appliances have a DPDT contactor allowing loads to be switched between phase 2/3 and phase 1, they can operate from either as required. A single phase only load can just connect to phase 1 and ignore the others.

The socket outlet would be able to signal its actual current rating to the appliance which could throw an error if connected to a supply it cannot operate on, or simply operate at reduced power (for example a cooker not allowing all rings to be on at once).

The designer would have the ability to distribute single phase loads to the desired phase by connecting that phase in the L1 position on the socket, which is the phase used in single phase mode.