ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Ring circuits again!

Better late than never: Here is the definition of long period of time. One hour.

Article here

On the Irish BS1363 standard:

Schuko was used until the 1940s and quite possibily until the 1960s in some cases. As I'm sure you're aware the UK equivilant was a bit of a confusing mix of BS546 based plug and socket systems some of which were 2 pin some 3 pin and of at least 4 different incompatble sizes!

Siemens and AEG were the main contractors to the ESB in the early days (and still are!) so a lot of their standard components were used (Neozed/Diazed & Schuko)

Schuko sockets still survive in old installations, some of which are still in use and schuko plugs can still be purchased in hardware stores.

In many cases however schuko sockets that are still installed in skirting boards or woodwork etc are simply dead, they're usually very unobtrusive and recessed into the skirting and removing them would have been more difficult than just leaving them in place but disconnected.

BS546 was used in its 3-pin form (usually only the 15amp version) during the 1950s (immediately Post WWII). The 2amp version was adopted later for special purposes like wallswitch controlled plug-in lamps. The 15amp version is common place in stage lighting rigs (more recently being replaced with the more resiliant standard european industrial connectors)

BS1363 was the predominant standard from 1960 onwards and was given legal standing later with IS401 & IS401/A which are required to be complied with by legislation, very similar to the UK but still inforcing standards that may still exsist .. e.g. schuko plugs on sale are referenced to CEE 7 & appropriate DIN standards)

Pre-1960 it was very unsual to carry appliences from location to location so wheather Schuko or BS546 was used was really of no consequence.

Post 1960 portable appliences became much more common place, people moved radios from room to room.. vacuum cleaners etc were in much more widespread use.

BS1363 added a little bit of extra protection (was child proof & fused). Wheather the fuse was actually adding protection or not the public percieved it to be safer.

It also makes providing sockets outlets that can actually provide a full 13Amp supply should they need to much easier. Wheather they're wired on a ring or on a radial (which can be rated 20amps instead of 16). In many older European installations bedroom sockets were often unsuitable for large loads as more outlets were carried on 1 16amp or 10amp radial (often only accepting narrower pin plugs) or in the old British system were often the physically smaller 2 or 5amp BS546 sockets to prevent large loads from being connected.

BS1363 & the ring circuit / heavier radials meant that portable heaters etc could be used much more effectively at any location in the house without over-loading the system.

As time has gone on the ring circuitry has also meant that generally the number of outlets per room in a UK/Irish house is much higher making them much more suitable for modern living.

Irish electricians tended to have frowned upon very large rings however and they're not quite as common as they are in the UK.

They use the same rating for the cable but tend to be much more conservative with the fusing arrangements sometimes opting for 20amp breakers rather than 32 and using less sockets per ring or using radials.

Generally an irish consumer unit will generally have at least 2 rows of breakers or diazed/neozed fuses (were un use until the mid 1980s, Neozed is still acceptable but considered old-fashioned and impractacal for the consumer.. a switch is easier to reset!).
RCD has been obligatory since 1980 and we require a double pole isolator switch (now on the bottom of the meter) and main fuse (typically 63amps) installed on the consumer unit before the RCD. This is to protect the consumer unit itself from catching fire in a serious overload situation.

The power company also has a sealed fuse before the meter. This is usually 63/80/100 amps and unless someone shorts the two lines coming into the meter itself its only purpose is to disconnect the entire supply.

[This message has been edited by djk (edited 05-05-2003).]

That makes for interesting reading, but just goes to highlight the concerns that have been expressed here at ECN about the ring -- That it is not foolproof and without very careful planning it is quite possible to overload the cables even without faults, such as a broken phase or neutral.

I note the document mentions the committees' desire to retain the U.K. ring circuit. Thinking of another thread, I don't doubt that it's same bunch who want to adopt the CENELEC-type brown/black/gray phase colors!

Allow me to quote myself:
Six months on from that comment, but I stand by it.

And whether the present committees want to retain the ring or not, if we ever do get a Europe-wide standard for wiring I can't see the British ring being a part of it.

Paul,
I reckon you'd have your work cut out for you getting a prevalent system like that banned wouldn't you?.
I mean it's everywhere in the UK, isn't it?.
Are you proposing to use a Radial system instead?.
How would wiring a house (with say 4 points on each floor) compare price-wise, between the two systems?.

Yes, the ring circuit is found in practically every house in Britain. Even though the ring has been in use over 50 years now, the IEE Regs. have always kept radial circuits in as alternative arrangements, although the allowable number of outlets, floor area served per circuit etc. have changed regularly.

I haven't sat down and worked out the price difference, but as far as new construction is concerned, I don't think it would make much difference. 2.5mm twin-&-earth cable runs about £15 per 100m drum, typical domestic type-B MCBs about £4 to £5 each. Extra labor is just going to be pulling a few extra cable runs, which on a new building is easy. Compared to the overall costs of £2000 upward, any extra cost would be negligible.

Paul,
When you think about it,
Radial circuits would be easier to install than Rings.
I realise that a lot your houses in the UK are two-storey, but dropping a single wire down a wall, has to be easier than tearing up floorboards to get to ring cables.
What are your thoughts?.

I promised I would not comment any further on this topic, but here goes.
It would not really be "easier" to wire a house with the radial system. You won't have fewer floorboards to lift, & you still have 2 cables at each point except the final one.
I have installed both systems, the only difference would be that in radial you do not have to return to the consumer unit from the final point.
Utilising the radial system would result in extra socket circuits being required in the average home, and consequently a larger distribution board with more mcb's.
Bottom line is it would be more expensive, but not a lot more, I've never sat down & worked it out.
It is quite acceptable under UK regs to use radial socket circuits, I often do, when installing a limited number of sockets in a location remote from the consumer unit.

I think ultimately the ring main will be abandoned in the UK, EU harmonization will ensure that. As long as what replaces it is a better, safer system, then that's OK.
Until then British sparkies will continue to favour the ring main.

I have to comment on David and Trumpy:

The radial circuit doesn't need two cables at each socket. In fact, this may be frown upon by some constructors. In modern offices, flexibility is very important. The higher rent per area unit compared to older offices is compensated for by more efficient use of the area. (Or at least they try to)

This means that walls come up and go down as the company reorganises. Only the ceiling, floor and structural walls (don't know what to call the walls you can't remove) remain fixed. Obviously, cables run from socket to socket aren't suitable in removable walls.

Ok, you could do a ring in the ceiling and spur down, but a radial layout seems simpler.

C-H,
No disrespect mate, we were referring to residential construction.
Also modern installation practices in the UK & NZ? prefer loop in wiring methods, ie. joints made at accessories, avoiding the use of joint boxes.
Installing joint boxes adds to the time taken & puts another weak spot in the system.

Stuctured office cabling systems are often based on radials for that reason.

I can't see the huge advantage of ring circuits. There are some minor advantages in terms of saving cable but in a typical house, at least here in Ireland, rings can be very difficult to install. Solid interior walls are common (even in new buildings) as are concrete or even stone floors etc. So the usual approach is to take radials up to the attic from the consumer unit and feed them back down into the rooms through conduits burried in plasterwork or through wall cavities. On the ground floor where there is a suspended wooden floor (most houses) it's easier to run cables down from the consumer unit as radials and out to points taking an under-floor route. If there's a concrete floor they go into the ceiling.

There are a lot of advantages to a modern radial system too:

1) Easier trouble shooting. If something does go wrong you can trace faults by a simple process of elimination.
2) Adding extra circuits tends to be easier as the Comsumer Unit (Fuseboard) tends to be bigger and more flexible.
3) Circuits likely to cause a trip more frequently are on their own MCBs.. e.g. the kitchen, utlility room etc.. so there's less chance of loosing power in your office when the kettle short circuits! (Unless there's only one RCD and its a ground fault)


Rings generally are only easier if wiring can be run room to room horizontally behind walls. Having each socket hooking into a ring in the ceiling / floor doesn't really present any great advantage.

In any western european country the cost of labour is by far the biggest part of the cost of an electrical installation. Cable and circuit breakers are relatively cheap.

What's the cost of a MCB in the UK?
or cable per meter?

Decorative fittings tend to whack up the price too...

I just fail to see the huge advantage of using rings.. they seem unnecessarily complicated.

[This message has been edited by djk (edited 05-10-2003).]