BAN THE USE OF RING MAINS OR NOT

[industryspark]

personally i cant see the problem with rings, we all know of the 'danger' when one is broken and agreed the breaks are often caused by DIYers............ but if done correctly then after working on the circuit (even changing socket fronts) continuity of conductors should be proved.

suppose you could make a case for instances where conductors burn away from the terminals but this i would think is rare and is the reason why PIR's should be performed at the times recommended.

 

[RF Lighting]

I like rings too.

I carry out a ring continuity test on every ring circuit I work on, as everybody should. Of the probably thousands of ring circuits I have tested over the years very few have loss of continuity.

Yes I have repaired plenty of ring circuits, and even one which had no earth continuity, and we found 4 separate breaks on this conductor (leaving some sockets with no earth)

But as has already been said, if properly installed and maintained, then I see no problem what so ever with ring circuits.

I do not like the argument of DIYers break rings so lets ban them.
DIYers do loads of stuff to electrical installations which leave them in a very unsafe condition.
A broken ring (which, remember is effectively only two 2.5mm² radials on a 32A MCB) is often the least dangerous bit of tinkering.

 

[mst]

Brillient thread chaps,

Ive never really thought of this before .....where connections are broken etc

But intresting comments coming from all and has made me wonder about rings too,tho at the end of the day if most ring work is carryed out by competant people then i cant really see too much of a problem.

And continulty tests should pick things up.

 

[dingbat]

Mr Diaz, you are absolutely correct in your observation and rings are an anachronism, introduced way back when the only non-fixed electrical appliances were a kettle and a three-bar electric fire.

There were relaxations on the rules regarding cable protection and certain assumptions made about loading and current-sharing, none of which are particularly valid today. Most rings are installed simply because few people actually think about what they are doing.

In the days of the Wylex standard four-way board a ring was a convenient way of supplying the whole house demand from a single fuseway, but with today's multi-way boards there is no real justification for them. A properly protected radial is far superior. (In any case a standard 'builder's ring' is a radial with a long return leg from the last socket!)

Testing a modified ring final circuit is a nightmare. Varying readings come not just from broken rings, spurs off spurs, etc, but also from plug-socket contact resistance variations and it is rare that a useful diagnosis of problems can be arrived at without a fair bit of dismantling.

 

[MR-DIAZ]

That´s the joys of forums then sensible people are discussing topics that have a little importance.

 

[dingbat]

...at the end of the day if most ring work is carryed out by competant people then i cant really see too much of a problem...

There's the first one!

And continulty tests should pick things up.

In an ideal world, yes, but as accessories age (see my post above)... The usual continuity problem shows end-to-end phase and neutral okay, then no cpc continuity... so let's play hunt the lost earth and pray it's only in one place.

Worse is when you get open circuit on each conductor, only to discover that each is broken at a different point on the ring. With a radial this would be a piece of pish to locate.

 

[JohnD]

But a kitchen ring (run all the way round the room 150mm above the worktop) is a very handy thing. Simple and economical to install, you can put in outlets every 600mm or more, no need to go down to the floor or up to the ceiling; very simple to add new accessories at any interval between existing ones. Ample power for the usual set of large appliances, and plenty of oytlets for the little ones.

I am now coming round to the view (as modern houses have need lots of sockets in all rooms) that it makes sense to run all the rings through the rooms horizontally chased into the walls at 450mm above the floor instead of going up and down all the time.

There is no need to go to the CU to continuity test - you can do it at any accessory (and easily do so every time you change a faceplate).

 

[dingbat]

I carry out a ring continuity test on every ring circuit I work on, as everybody should.

And both cross-connections? I bet most don't bother, especially with the phase-neutral one.

Of the probably thousands of ring circuits I have tested over the years very few have loss of continuity.

Yes I have repaired plenty of ring circuits, and even one which had no earth continuity, and we found 4 separate breaks on this conductor (leaving some sockets with no earth)

Non-continuous cpcs must be the second most common problem I come across... spurs off spurs being number one.

 

[dingbat]

But a kitchen ring (run all the way round the room 150mm above the worktop) is a very handy thing.

... unless you have (as is very common in older houses) a solid kitchen floor with a tiled bathroom floor above!

Horses for courses, though. And my main objections to rings are based on my daily experiences with DIY/builder/kitchen-fitter aberrations. If a new circuit (of any configuration) is correctly designed and with sufficient outlets it shouldn't require any hacking about.

 

[JohnD]

...
unless you have (as is very common in older houses) a solid kitchen floor with a tiled bathroom floor above!

Ha ha! It's all chased into the walls, horizontally! No need to go into the floor or the ceiling! Easy peasy!

 

[MR-DIAZ]

Good input Dingbat.

For your information I like the IEE regulations as they are one of the strictest in the would. It helps that there is also a massive range of materials that can be found in the UK. But with working aboard for some time i can now see there are different ways to prepare electrical installations and i am in NO WAY saying that the Spanish regulations are the better of the two. But on the 18th of September 2003 entered a completely new set of regulations here. what was once very common here with reference to radials changed to all connections had to be made within a inspection box i.e instead of looping from socket to socket as in a traditional radial all interconnection have to be made via inspection boxes mean there is only every 3 cables at every socket outlet. If there's a problem it´s normally in one place or the other ( inspection box or socket ,this system is very easy to find faults and just disconnect one leg without really losing the majority of power points on the installation. )

 

[dingbat]

And you get past the doorways, how, exactly?

I generally run horizontally between close-together accessories, with drops to unswitched sockets below DP isolators, etc, but why bother with a ring when you could use two 20 amp radials and get 40A load capacity instead of 32 and have a better degree of discrimination??

In any case, as i said, it's horses for courses and if a ring is the best option (a slightly dodgy relaxation of the circuit design rules thought it is) then why not?

But here's a thought: The most usual argument in favour of rings is the use of smaller cable for higher loads due to load sharing in each leg of the ring. But if your load is a couple of meters from the CU on a 20m long ring, where does 90% of the current actually flow? Not much distribution there is there?

 

[dingbat]

Mr D, I have lately come round very much to the idea of multiple distribution circuits. It makes absolute sense to have a greater number of smaller, simpler, locally protected circuits and in cost terms it makes very little difference.

 

[MR-DIAZ]

On average the price of work has gone up on this type of system especially with copper prices going through the roof.

It just makes a very good ( well to me ) installation to have in a room, 1 inspection box, fed from the main board that then feeds everything within that room. Simple.

As for the remark on :-

if your load is a couple of meters from the CU on a 20m long ring, where does 90% of the current actually flow? Not much distribution there is there?

is a defect on the regs for normal use let alone in fault conditions which only goes in favor of changing the way ring final circuits ( or should i say how socket outlets are wired ) are wired.

 

[Adam_151]

But here's a thought: The most usual argument in favour of rings is the use of smaller cable for higher loads due to load sharing in each leg of the ring. But if your load is a couple of meters from the CU on a 20m long ring, where does 90% of the current actually flow? Not much distribution there is there?

I'm sure I remember seeing some official thing from the iee on this in one of the wiring matters magazines, unsuprisingly the guidence is that the designer should try and design to minimise the chances of such an inbalence occuring...

so back to that builders rfc and not installing them ...I had an argument on here a while back with someone who didn't agree that it was bad design practice

...These new housing estates, one rfc per floor, CU in kitchen...dosen't seem like its going to be a very good design in respect of the above (I don't actually know if the kitchen is at one end of the rfc, but I suspect it is) I suppose thats one reason when using rfc to put the kitchen on its own rfc, even though the load in the rest of the downstairs is going to be quite insignificant, is that you don't end up with a rfc with the heavy load on one end...