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

Yes, the title is flemish. We also have the french version (title).
>What do you do if you add an extra socket in a room with old ungrounded cables?
The only solution then is to pull a ground wire. By you?
>It seemed like the only type Castorama had. I can imagine that they are not as good as ordinary breakers.
It IS the only make which makes them. No, they're not as good as the ordinary ones.
>They must be pretty small? Yes
>I meant double width 4 pole, but expressed myself poorly. No, they dont exist yet in double width 4 pole. It is a very recent product.
>The socket you have in your post looks like it has a recessed engagement face? I'm I right? (Ours look just the same!)
Yes, ours is also recessed.
The ones with ground pin; we have 2 models one half recessed and one full recessed.

>The only solution then is to pull a ground wire. By you?

Put an ungrounded socket, unless you are going to do major changes to the wiring. (I don't know where the line is drawn really.)

>Yes, ours is also recessed. The ones with ground pin;
>we have 2 models one half recessed and one full recessed.

Ok, I can see the difference. Why are there two types? Full recessed in wet areas? Does the ground pin protrude beyond the socket in the half recessed version?

>...unless you are going to do major changes to the wiring. (I don't know where the line is drawn really.)

By us it's the same law, but I would consider this a major change.
>Why are there two types?
Half recessed for places where you don't have enough space behind the socket e.g. to make more connections behind a socket.
>Does the ground pin protrude beyond the socket in the half recessed version?
Yes, but it has a "ring" which protrudes around the plug to protect the pin.

Paul,
With your disdain for a Ring Circuit, have you actually had a problem with a broken Neutral conductor, where this would cause an over-current in the remaining part of the circuit?.
Can a Ring Circuit be protected by an RCD, under your Regulations?.
Is the UK, coming into line, more with international(EU), hence the change in Regs
between the UK and the EU.

Yes, I've seen a broken neutral on a ring frequently. A broken phase conductor also results in the same problem. I've also found "rings" with a break on all conductors, usually the result of a bodged DIY extension.

Rings most certainly can be protected by an RCD; indeed in some cases they would be required to have such protection (e.g. a house using TT grounding where there is a main RCD/GFI).

There has been a gradual move toward Britain adopting common standards with Europe over the last couple of decades (and in a few cases before that. e.g. adoption of the common brown-blue-green/yellow flex colors and metric size cables in 1970). Circuit breakers which were once rated 5, 15, 30A for example are now often 6, 16, 32A.

There are still stumbling blocks which the various national bodies disagree on, and the basic circuit arrangement seems to be one. The IEE remains firmly attached to the ring circuit with fused plugs, a system not used anywhere else in Europe except Ireland, and even they seem to be adopting Continental standards now.

On the Ireland thing:

I've been in contact with an Irishman and according to him the BS 1363 is and remains the only socket in use in Ireland. However, the Irish system was originally built by German companies, and thus the German voltages (220/380), fuses (Diazed, Neozed) and the Schuko plug found their way to Ireland. The Schuko was discontinued when the BS 1363 was introduced.

I can see two possible explanations for the reports of Schukos or French sockets in Ireland. a) Someone has found an really old socket. b) Someone has for some reason installed them, e.g. an hotel as a service for European guests.

BTW. An interesting topic popped up at uk.d-i-y: Ring mains are now required to be designed in such a way that the load on each leg does not exceed 20A.

Thanks for that C-H. It certainly sounds a plausible explanation. I don't suppose you happened to find out exactly when the BS1363 plug was introduced as an official Irish standard?

Designing the ring so that the current doesn't exceed 20A on any part would require a certain minimum length of cable from distribution panel to the first socket, worked out as a percentage of the overall ring length.

>I don't suppose you happened to find out
>exactly when the BS1363 plug was introduced
>as an official Irish standard?

No, sorry!

>Designing the ring so that the current
>doesn't exceed 20A on any part would
>require a certain minimum length of cable
>from distribution panel to the first
>socket, worked out as a percentage of the
>overall ring length.

You can do the calculations, but someone had calculated that you "loose" 16% at the start and just as much at the end of the ring, making one third of the ring "passive".

C-H & Paul
The new ring main design rule in BS7671: 2001, Amendment No.1, February 2002, ammends Reg 433-02-04 to read:
"....Such ring final circuits are deemed to meet the requirements of Reg 433-02-01 if the current-carrying capacity (Iz) of the cable is not less than 20A, and if, under the intended conditions of use, the load current in any part of the ring is unlikely to exceed FOR LONG PERIODS the current-carrying capacity (Iz) of the cable."

These ammendments are available as a free download from the IEE website; www.iee.org.uk, there are also ammendments to the current ratings for BS 6004 flat twin & earth cables.

Hope this helps.

[This message has been edited by David UK (edited 11-04-2002).]

Thanks for the details. I hadn't seen that amendment yet.

I guess it leaves the door wide open for varying interpretations of what constitutes "intended use" and how one defines a "long period." Typical vague IEE wording.

I'd still rather just see rings abandoned entirely, although I know I'm in the minority in the UK for having that view.