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

DJK,

Re the cost of cable and MCBs, from my last post above:
If we look at the extra cost of a larger panel (consumer unit), it adds very little. For example, in my usual supplier's current catalog a Wylex insulated NH range 100A panel is £16.29 for the 5-way version and £24.69 for the 14-way (plus VAT). MCBs for this particular panel are £4.59 each, or down to £3.79 each in larger quantities. As you mentioned, compared to the other costs involved in a new installation, the possible extra cost of wiring with radial circuits is small.

My absolute favourite is the good old Austrian/German radial layout, also used in Spain and many other countries.



Troubleshooting can't be easier, even if you have no idea where which wire runs you can guess easily. For example, if you have a receptacle and there's no junction box directly above you start looking to the left and to the right. If you find a box for example a box to the left with 2 or 3 wires leaving to the right you can be pretty sure these are the wires feeding the receptacle. And in most cases you have only one set of wires at each outlet/switch. I do almost all my new wiring this way. Only in severe emergencies I run wires down to the floor and around the walls 30cm above the floor. (precisely this happened once in my life, since there were windows on both sides of the room, and I'd have had to go up very close to the ceiling to pass above the windows, so I decided to go beneath.)

Ranger,
What??.
We don't even use the junction box anymore in lighting circuits, unless its really necessary(alterations, etc).
All our joins are done at switches and light-fittings, although downlights make it harder, as they never have a loop terminal.

Ugly!
Starts to come up with new construction here too, but all retrofitting is done as I described. Switch boxes aren'T too big, I hate connections inside them, it makes almost impossible to get the device in. only junction boxes for me, the larger the better! Light fixtures, especially the very common pendants don't have any wiring space, only a strip connector covered by a plastic cup turned upside down. Making joints up there would mean to have a bunch of wires and conduits sticking out of a hole in the ceiling and you have to put lots of strip connectors into the "yoghurt can". New construction often puts 1 large junction box per room above a trap door in the drywall. But round and square junction boxes (from 10x10 cm up, I've seen 30x30 cm ones) are still widely used.

Hi I am currently in Australia but have worked on ring circuits in the UK personally I do not have a problem with ring or radial the debate has been around since Noah wired his boat shed. With regard to the current demand, that is covered in domestic situations by diversity or maximum demand. I do not know of too many houses where appliances in general use draw 20A continuous anyway. The only real problem I have had with rings was where a house I worked on had the ring connected to two individual fuses (yikes lucky I checked the supply before working on it)and they were 30A each! thats all folks! love the forum.
Steve.

PAUL UK


I think ring main circuits are not a bad way to install your power points, only there is possible downfalls to the system!One regulation i do think they should take a step back on is to increase the amount of spurs off any one socket to maybe two, taken into account the area it is situated this would save unnessarcery joints while exstending the ring.

I often wounder what would happen if a ring circuit was serving close to its carring capacity, and there was to be a break in the ring! Worse still the break could be a loose connection in the circuit breaker device, meaning your 100m2 floor area ring has now become a radial with a cable current carring capacity of around 23 amps (if buried in a wall) with a 32 amp rating on your protection device!!

Just a thought thats all.

I'm sure it wouldn't be altogether impossible to come up with a MCB or similar unit that could check the integrity of a ring and cut the power if it was not intact.

It could be done electronically by simply sending either a continious or intermittent signal down one side of the ring and if it doesn't come back on the otherside trip the MCB. Similar technologies exsist for controlling lamps etc remotely via piggybacking signaling onto the power system of a house.

Generally, unlike radial installations there are only 2 or 3 rings. So it wouldn't be economically prohibitive. They wouldn't necessarily have to be on the fuse board either. You could wire them in after it across the 2 X L and 2 X N of the ring (perhaps the earth integrity could be tested too).

Such a system could be made to fit into a standard DIN rail consumer unit.. even if it occupied a bit more space than a MCB..

It would be a pricy sollution but then again some people considered RCDs excessively pricy and unnecessary for years. If it prevented house fires it might be worth it.

Then again how many broken rings have caused house fires?

DIY jobs on radial circuitry is often just as fire-prone.

On a subsequent point:

I'd be 100% happy with the ring circuit idea if it included that / similar system and changeda few details

1)Face up to the reality that 90% of appliences regardless of their wattage/fusing requirements are fused at 13amps. Given the fact that they're all specified for use with 16amp european outlets this is not a problem.

2)If the UK is going to remain with BS1363 in the long term it could at least introduce fused sockets (at 13amps) that allow the connection of Europlugs (the narrow type only!) as well as BS1363. This would remove the need to jam europlugs into sockets having released the shutters with a screwdriver/pencil etc which does happen quite a lot. It could be designed in such a way as to exclude the larger pinned schuko/french plugs requiring grounding and automatically is incompatable with Italian/Danish/Swiss grounded plugs due to their prodruding pins.
It would prevent any applience from being plugged directly, for any reason, into a 32amp ring. (Poorly designed unfused adaptors, unfused transformer plugs etc etc)
I know it's a comprimise sollution but it would bridge a gap between the UK and European systems much like the Schuko/French design (CEE 7/7)

These sockets could be required on all new installations .. ring or radial. Old sockets simply wouldn't be able to accept Europlugs (unless you force them open.. which already happens)

I would see no reason to change the specificiation for a normal BS1363 plug though. an extra fuse never did anyone any harm and they're a good design.

On price/practicality.. sockets are expensive once-off investments. Many of them have switches etc in the uk so adding a fuse isn't a huge deal. I've seen flush fitted dimmer light switches in Ireland which have BS 1363 fuses slotted neatly into a fuse carrier the bottom for example. I'm sure a neat sollution for sockets could be developed.. (perhaps a plug in fuse like a car fuse?)

Such a socket would be very useful to the hotel industry for example.

3) For items that require specifically low fusing.. shavers and perhaps some lamps (with old style cords) or anything that needs to be fused at lower ratings: produce moulded on or rewirable plugs (for older fittings) that only accept the correct fuse type.
E.g. a 3amp plug should only accept a 3amp fuse! I'm sure this could be easily achieved.
Most people just jam a 13amp fuse in when a 3amp one blows not realising why its there in the first place. This is the very reason that systems like Diazed/Neozed are designed to make it impossible to overfuse a circuit.

Perhaps non-overfusable version of BS1363 could be developed? BS1363/B ?

As for other safety requirements: read my post in: https://www.electrical-contractor.net/ubb/Forum9/HTML/000303.html (Re offically proposed RCD requirements in Ireland)
Specifically:
From an ETCI (Electrotechnical Council of Ireland) proposal:
Recommend (to TC2) that all 230/400V electrical circuits be protected by independent RCDs, i.e. sockets protected by one RCD, lights by another
and fixed installations by one or more other RCDs. Smoke detectors and associated emergency lighting should make this proposal easier.
Sound reasonable?

[This message has been edited by djk (edited 05-14-2003).]

Steve, James,
Welcome to ECN!

I'm come across a ring where each end terminates on a separate fuse as well. It just goes to show how inventive the DIY bodger can be at coming up with ways to get it wrong!

The scope for bad connections causing an overload is one of my concerns over the system. Sure, a bad connection can cause problems anywhere, but too often I've found a ring with broken continuity on one line. The householder doesn't notice, of course, because every outlet still has power. Maybe the chances are that his use of the circuit won't ever cause appreciable overloading of the single cables now feeding the outlets. but it's really an accident waiting to happen.

Are there any statistics on how often a broken and overloaded ring has started a fire? I very much doubt it. I think the investigators just chalk up any wiring-related fire to "electrical fault" and leave it at that.

The continuity-checking ring-circuit breaker sounds an interesting idea, but just imagine how much the things would cost when they first appeared. I suspect that by the time they were being made in sufficient quantities to make them reasonably priced that the IEE and other UK institutions would have finally capitulated and abandoned the ring circuit.

pauluk

What do you think should be done about this obvious danger? Do you think radials should be used or some other method?

once heard of a tree like system with a main line ( trunk ) 4mm2 and branch like legs jointed off in 2.5mm2.

NIGHTMARE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!