Electrics in General - Stupid Question

[conroyster]

Hi guys, could someone gave me, or direct me to, a general overview of how a house is wired. Am I right in thinking that wire/cable goes from the mains all around the house, then back to the mains? Are all those components (sockets/lights) on the same ring dependent on one another, i.e. If a socket is disconnected will it caused all other sockets on that ring to cease working.

I ask this question as someone who is interested in electrics, but has no training. This is purely for information only, I am not planning on rewiring my own house (maybe a friends ).

Thanks.

 

[dextrous]

You are describing a ring circuit. If you break the circuit, then electricity can still reach all the other sockets either side of it as both sides go back to the consumer unit.

Light circuits are radial in that it doesn't form a complete loop. If you break the circuit then all later fittings in that circuit will not work.

It is becoming increasingly popular to run socket circuits as radials using a thicker cable, for safety reasons.

 

[conroyster]

Wow, thanks for the quick response, but I have a follow up question:

For a ring circuit if we break into the ring in order to add a socket and then subsequently remove the socket and do not fix the ring, how will the ring circuit remain complete?

Apologies if these questions are naive, but I am intrigued by how this works.

If you have any links or references that explain both the a ring and radial circuit in greater details it would be much appreciated.

 

[1john]

it is also becoming harder to install ring mains

 

[ban-all-sheds]

• //www.diynot.com/wiki/electrics
• //www.diynot.com/forums/viewtopic.php?p=75416#75416
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/electricity.html
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/domesticinstallations.html
• //www.diynot.com/forums/viewtopic.php?t=7553
  

 

[electronicsuk]

it is also becoming harder to install ring mains

Is it?

 

[dextrous]

Wow, thanks for the quick response, but I have a follow up question:

For a ring circuit if we break into the ring in order to add a socket and then subsequently remove the socket and do not fix the ring, how will the ring circuit remain complete?

Apologies if these questions are naive, but I am intrigued by how this works.

If you have any links or references that explain both the a ring and radial circuit in greater details it would be much appreciated.

BAS has provided the sources which should be read to begin to give you the basics.

As for your question - I don't understand what you mean?

 

[dextrous]

it is also becoming harder to install ring mains

Is it?

Age gets to us all in the end

 

[ban-all-sheds]

it is also becoming harder to install ring mains

Is it?

Yes, because the increasing amount of thermal insulation in houses is making it harder to achieve an Iz of 20A with 2.5mm².

 

[conroyster]

Thanks for the sources, I will take a look at them.

My question was regards to breaks in the ring, and how the other sockets on the ring could continue to work if one socket was disconnected, i.e. the sockets wires remain disconnected and not placed in a junction box.

My misunderstanding of a ring curcuit may come from similar terminology of computer networks. In computer networks if a single terminal in the ring fails then the whole network fails (source: http://en.wikipedia.org/wiki/Network_topology#Ring)

 

[dextrous]

Because both cables, to the left and right of the socket go back to the consumer unit.

Unlike the network ring, each socket doesn't have the effect of boosting the current as it passes through it. Also, in the example that you cite, nowhere on the hexagonal array is there a central power supply, or even a server.

 

[ColJack]

it is also becoming harder to install ring mains

Is it?

Yes, because the increasing amount of thermal insulation in houses is making it harder to achieve an Iz of 20A with 2.5mm².

so then it's not getting harder to install rings at all..
just 2.5mm² rings..
while there are "standard circuits", every circuit should be designed for it's own needs..

it's perfectly reasonabe to install a 4mm² ring..

as for the ring, if you cut it it is no longer a ring, it's a radial with a branch at source.. ( which should then have it's breaker ratings adjusted ot suit )

to use an analogy, if you have a hosepipe and put both ends onto the tap, and then cut it somewhere, the water comes out of both sides of the cut..
if you then cut it again somewhere else, the bit of hose between the cuts will have no water coming out, but the bits that go back to the tap will..
( we're using theoretical water here that stays in the pipe unless there's pressure behind it.. )

same thing if you split a ring..

 

[conroyster]

Thanks for all the feedback. I think I understand how the electrical ring circuit works now.

A broken ring circuit, were a socket is disconnected, acts as 2 radial circuits, one in each direction around the ring. Therefore as you stated, the socket to the left and right of the disconnected socket will remain connected to the consumer unit.

The analogy between a computer ring network and electrical ring circuit falls down because in the computer network data can only go 1 way around the ring. But in electrical terms, electricity will flow in both directions around the ring. An obvious difference that I failed to spot.

Thank you all for your patience.

 

[Taylortwocities]

The main problem with ring circuits is if the ring has a break in it.

Firstly it will not be noticed as all of the sockets will continue to work.

Secondly (as noted above) the circuit will then effectively be two radial circuits of 2.5mm² coming from the 32amp mcb in the consumer unit. This is a bad thing because 2.5mm² cable cannot support 32amps. The cable could then melt/catch fire under high load conditions.

 

[dextrous]

... whereas reducing the MCB to 16A which 2.5mm will support, or having a radial with 4mm cable with 32A circumvents these problems. The latter has the added advantage that should a break in the circuit occurs, it wll be noticed.

Suppose a compromise would be to remove one end of a ring from the CU and replace with a 16A breaker - but then doesn't this limit the area that a 2.5mm radial can supply, or something?

Anyway, I'm off before BAS tells me off