ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades Some german electrical info

Well, as the british use ring circuits with 32A fuses/breakers it isn't. So the plug fuse is there to protect both cord and appliance. Ring circuits are actually 2 2.5mm2 cables paralleled, but not run in parallel but forming a huge ring (for example the phase wire goes from the breaker to socket #1, from there to socket #2, socket #3,... and then finally back to the same breaker). A pretty complex setup and we've had quite some discussions about it in the past.

ah, i didnt know the british travel that high Amped to their outlets.

why does the phase go back to the same breaker?? why a ring, not a "tree" distribution?

The major advantage is that you can install a lot more outlets using a lot less wiring.

The cables "loop in" and "loop out" of each outlet and carry on to the next outlet and then back to the MCB on the distribution board.

Power is fed to the outlets in 2 directions i.e. on both sides of the ring so the cable does not need to be as thick.



They're also used in Ireland too although in modern installations we tend to mix ring circuits with a lot of 20A radial circuits. As the plugs are fused individually a 20A radial circuit can supply quite a few sockets. From what I've observed most of the rest of Europe tends to use 16A radials, which are common in older installations here.

A more typical ring circuit:



fixed appliences are connected via a fused spur which looks like this:




The inside of a BS1363 plug: Note fuse:






[This message has been edited by djk (edited 12-02-2003).]

i learned! thanks!

Andy,

The ring circuit was introduced here in the late 1940s, along with the BS1363 (fused 13A) plug.

Here are some links to old threads which you might find interesting (feel free to add to them! ):

Ring circuits U.K. style

Ring circuits revisited

Ring circuits again!


[This message has been edited by pauluk (edited 12-04-2003).]

i didnt read everything now, but i read, and i couldnt find a response to for example this question:

scenario - 3 Outlets in a ring, first Outlet loaded with 15A, second outlet loaded with 15A, interruption of the phase at the terminal of the third outlet.

is it right that then the whole 30A will flow only from one side into the ring, overloading the 2.5mm² wire but not blowing the fuse?

ah, i found it now in the second link.
well, thats a safety risk, isn't it?

The possibility of a break resulting in an overload is indeed a very real risk, whether that break occurs through damage or incompetent DIY work.

I've seen rings with a break on the line side at one point and a break in the neutral somewhere else in the ring.

I think despite the IEE's support for the ring system that that single fundemental flaw would justify Cenelec banning it in new installations. Is simply isn't fundementally safe and relies on good installation practice.

and
Despite the fact that I think BS1363 is a good, sturdy well designed connector the fact that it's possible to insert a Europlug into the outlet and end up with a portable applience being protected only by a 32A fuse is unacceptably dangerous.
Most people know how to open a UK socket shutters with a pencil and you do see tourists and locals alike using 2-pin plugs in BS1363 outlets with no adaptor.

The simple fact is that it works quite well, the sockets appear to generally make good contact with the europlugs and hold them very firmly in place.

Since all EU flexible cables are designed to handle 16A it would make an a lot more sense to fuse the sockets than the plugs.

Do you think we could ever see a fused UK socket that is designed to accept 3-pin UK plugs and thin 2-pin Europlugs?

whow,i didnt know that you can fit an euro plug into the british socket.

different question:
is 4mm² wire twice the expensive the 2.5 is?

if not, one could wire the outlets in radial style fused 32A with no safety risk, and would save the cable of the way back to the panel.