one for the pro's to debate...

[GaryMo]

I still think you're reading too much into 433.2.2 and that the actual meaning is outlets prior to the end of line socket - a radial with two accessories connected capable of drawing more than 26A.

no, I'm reading exactly what is there and no more.. you're the one adding meaning to it by interpreting it to suit your point of view....

I'm looking at it from the perspective of 433.1.5 whilst it's been mentioned that only accessories to BS 1363 should be used which kind of take away the argument of unfused plugs and splitters.

Did you think this thread would hit 7 pages when you started it?

 

[ColJack]

Unfused splitters are not BS 1363 accessories.

and yet they are / were freely available to anyone who want's one.... and fit conveniently into a BS1363 socket..

the BS 1363 is a work around for the flaws of the RFC.. as I believe BAS may have said on occasion..?

in all of the world, i think that there is only us that put fuses into plugs to make it acceptible to have a circuit that uses cable that would melt before the breaker operated..

 

[dingbat]

Well, thank goodness they came to their senses in 1947 and realised they were trying to solve a problem that didn't exist. If it hadn't been for that last-minute injection of common sense, sparks would have been installing rings left, right and Chelsea without a bleeding clue as to what they were doing or why.

As I say, thank goodness the committee came to their collective sense in time to prevent that travesty of electrical design ever coming into popular use... what a nightmare THAT would have been...

...just imagine, generations of confused electricians, incorrectly installing circuits they had no idea how to test and blindly believing them to be the best thing since sliced bread... phew, narrow escape, eh?











..and then I woke up.

AAAAAAAAAAAaaaaargh!!!

 

[NotHimAgain]

Well I am not going to debate RFC in general - we would be here all week .

Melt the cable - don't you think that is just a slight exaggeration given that the ratings are based on an ambient temperature of 30 degrees and assume that the circuit is operating at 70 degrees before overload .

Show me the bodies .

 

[Spark123]

Had one not so long back where someone had plugged their tumble drier, washing machine and dishwasher into a double socket (using an unfused adaptor).
The socket had decided to melt
The socket was an unfused spur from a RFC below the worktop in a kitchen, the cable feeding it was still fine.

 

[ColJack]

I'm looking at it from the perspective of 433.1.5 whilst it's been mentioned that only accessories to BS 1363 should be used which kind of take away the argument of unfused plugs and splitters.

Did you think this thread would hit 7 pages when you started it?

433.1.5 deals specifically with ring final circuits..
it mentions spurs from it, both fused and unfused, but it only specifies the requirements of the cables for the ring.. NOT the spurs from it..

it's the common interpretation that that means that it's ok to have an unfused spur in 2.5mm feeding one single or double socket, but it also mentions cable with a minimum current carrying capacity of 20A..
now, going by that then under installation conditions that de-rate the 2.5mm to 20A, it would satisfy the regulation but a double socket can draw 26A ( but lets not overlook that a BS 1363 fuse will allow a sustained overload of a few amps for a duration.. I can't find the curves in the regs book anymore but it takes 95A to blow a 13A in 0.4 seconds..)..

 

[NotHimAgain]

The 'fusing factor' is accomodated in the current rating tables.

 

[mfarrow]

why is it ok to have a spur from a ring but not a radial on it's own?

I'm sure if we wrote into the IEE and asked them the answer would form something to do with diversity and base load being an additional factor and therefore you can assume there will be some loading on the ring which would allow the CPD to operate before the spur cable melted itself.

On a spur from a 30A/32A CPD all on its own, you cannot make this base load allowance, so you're limited to the cable's current carrying capacity on the other end... which, as I've deduced, is likely to be just only a fused outlet.

At least that's what I think they'll tell us, they can't really say it's for historical context. Anyone got a pen and paper handy?

 

[securespark]

in all of the world, i think that there is only us that put fuses into plugs to make it acceptible to have a circuit that uses cable that would melt before the breaker operated..

Singapore at least have 1363 outlets like us and I think a coupla other countries but not sure which.

This from a website:

Those countries not followed by "(exclusive)" share the 1363 system with other standards.

United kingdom of Great Britain and Northern Ireland (exclusive)
Ireland (exclusive)
Singapore (exclusive)
Malaysia (exclusive)
Cyprus
Malta
Gibraltar
Botswana
Ghana
Hong Kong
Macau
Brunei
Oman
Kenya
Iraq
Qatar

 

[ColJack]

yes they have fused plugs, but you didn't read the whole sentance in it's context did you????

i said that we're the only ones i know of that use fused plugs to make it ok to use unprotected undersized cables in a circuit.... or at least that's what I was trying to say..

 

[securespark]

I know that Singapore, as well as adopting 1363 accessories has also adopted the RFC. Don't know about the others.

 

[Paul_C]

An Irish contact told me a couple of years ago that while ring finals were/are used in the R.o.I., they were never as widespread as in the U.K., and radials tended to be used as frequently. I understand that Shucko sockets were also installed quite widely in the 1950's/60's, before BS1363 started to become the norm (and BS1363 is copied into an Irish standard number as well, although I can't recall the number offhand).

 

[NotHimAgain]

Note: I have edited my original post as I found more info on Irish rings .

I have a copy of the Irish regulations - valid in 1991.

These do permit BS 1363 socket outlets (I.S 411) and they do permit ring mains [583]. They use the 0.67 factor for cable rating as we did. They also have separate regulations concerning fused and non fused spurs very similar to ours. Annex 58A describes a ring final circuit formed using 2.5mm2 conductors and protected by a 35A fuse.

The Irish regulations use appendix 4 data from BS 7671 and reference many other British Standards. However, they tend to follow the original IEC / CENELEC documents closer than we have done in the past. This makes them a good source when trying to determine just what the original requirements were before JPEL/64 mangled them .

BTW they had RCD protection on ALL socket outlets way back in 1991.

Now how about this - the ring circuit continuity test [613.3] is described as verification of continuity of the ring conductors - and in Annex 61A it states that it is NOT intended to verify values of resistance. I can hear the bell ringing .

I have worked with contractors in Ireland back in the 70's - I did not see any TWE cable or ring mains come to that.