Electrics in General - Stupid Question

[plugwash]

one problem with 4mm 32A radials is that they are fairly marginal design, any grouping factors, insulation etc is likely to push them over the edge into noncompliance.

You could use 6mm instead but even that may not be enough with high insulation levels and it will make termination a PITA and branching virtually impossible.

 

[dextrous]

one problem with 4mm 32A radials is that they are fairly marginal design, any grouping factors, insulation etc is likely to push them over the edge into noncompliance.

You could use 6mm instead but even that may not be enough with high insulation levels and it will make termination a PITA and branching virtually impossible.

I get the hint. Back to plumbing I go, with my tail between my legs.

 

[Taylortwocities]

Yes but nobody notices if there is a break in the ring until an inspection takes place and the ring continuity is checked.
Up until that point (10 years, if ever in domestics) the wiring is at risk.

You could put in a 32A radial final, but the topic is ring finals.

Edit: sorry didn't see things had rolled onto page 2.

 

[1john]

Yes but nobody notices if there is a break in the ring until an inspection takes place and the ring continuity is checked.
.

Or things start smouldering, i install rings, have always done, but don't like the design in general, they can work when faulty, kitchen fitters would be prime for dirconnecting them and taking them across two work surfaces and never reconnecting them. seen extensions by builders in the past with the ring main looped off the ring main

The main problem being with wiring is that is it works, joe bloggs is happy enough with that i feel.

I wouldn't fancy getting two 6.0mm cables into some of the flat plate sockets on the market and i certainly wouldn't want to tell the customer the cost of installing such a ring final circuit.

 

[Paul_C]

Ring final circuits are a very British thing, not used in most other countries where radial circuits are the norm for everything.

I've never really been keen on domestic ring circuits for a variety of reasons. The potential risk from a broken conductor has been discussed already, but there are other concerns. It's possible for an unfused spur to be overloaded, even though considered unlikely, especially so with spurs wired to the older editions of the Regs. which permitted two single sockets on such a spur, which could be in different rooms. There's also the point that given a heavy enough load close to one end of the ring, it's quite possible to exceed the ratings of the short leg of the ring from that point back to the distribution panel.

 

[electronicsuk]

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.

The same would be true of any circuit, surely. Ring finals in 4mmsq aren't all that uncommon now, and no doubt the same design current with a radial would require 6mmsq or more.

 

[ban-all-sheds]

The same would be true of any circuit, surely.

Yes, but with radials you have the added flexibility of changing the OPD rating as well as changing the cable size - with ring finals you're stuck with 32A.

 

[ColJack]

no you're not, there's nothing to say you can't install a 6mm ring or a 20A ring.....

 

[mikhailfaradayski]

no you're not, there's nothing to say you can't install a 6mm ring or a 20A ring.....

but why would you want to?

 

[electronicsuk]

no you're not, there's nothing to say you can't install a 6mm ring or a 20A ring.....

but why would you want to?

You probably wouldn't want to install a 6mm ring as it would be rather unwieldy trying to squeeze it all into the backbox and indeed the accessories, but the same would be true of a radial in that size conductor.

You might want to downrate the protective device if correction factors wouldn't allow a 32A circuit - you'd still likely be using smaller cable than a circuit of the same rating in a radial configuration.

 

[mikhailfaradayski]

seems a bit messy,

i wonder if there are any sparks out there who have installed more than one socket outlet circuit using 6mm? or if their first time was also the last due to how awkward it was.

I dont really understand why UK sparks hold the ring-final with such high regard. IMO they are open to abuse and require a bit more effort when testing them.

Someone may choose to down-rate an existing circuit due to installation of insulation at a later date, but why would anybody bother to install a 20A ring? How would that make life easier?

 

[Spark123]

I don't think a 20A RFC is recognised by the regs?

 

[electronicsuk]

I don't think a 20A RFC is recognised by the regs?

That's a good point actually. Mind you, I think it would be relatively easy to stand up in court and prove it to be safe. Compliance with building regs may be another matter.

 

[Paul_C]

I think it would be relatively easy to stand up in court and prove it to be safe. Compliance with building regs may be another matter.

Building Regulations: "Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installation from fire or injury."

I know our judicial system has gone completely off the rails in many respects, but I don't see how something which has been proven to be safe to the satisfaction of a court could then not be in compliance with that very basic requirement of the building regs.

 

[ban-all-sheds]

I don't think a 20A RFC is recognised by the regs?

It's not - 433.1.5.