one for the pro's to debate...

[mfarrow]

Why though, what's the difference between there being an extra two conductors in the same terminal?

Oh I see your point.

To be honest I don't know as I didn't write the regulation, other than 433.1.5 says "Accessories to BS 1363 may be supplied through a ring final circuit, with or without unfused spurs". It doesn't mention where in the circuit these accessories can or cannot be, just that they're all allowed (a point reinforced by Appendix 15). Your right, apart from the added two conductors the conditions are electrically identical.

 

[GaryMo]

Sorry I've spent so long looking at references to 433.2.2(ii) that I completely ignored 433.2.2(i). Yes there is no length limit.

And no I hadn't forgotten about the requirements to protect against fault current, just didn't think of mentioning it.

You didn't see the paragraph directly above it, between 433.2.2 and 433.2.2(ii)?

That's the whole idea of 433.2.2(i), that the conductors would be protected against fault current.

 

[ColJack]

again though, sub paragraph (i) and (ii) only come into effect IF the cable has no branches OR outlets for current using equipment.. which a SOCKET is..
it has no internal fusing to it so you cannot rely on the fuse of whatever is plugged in as you don't KNOW for certain that there WILL be a fuse there at that point..

 

[mfarrow]

You didn't see the paragraph directly above it, between 433.2.2 and 433.2.2(ii)?

Again, no. I must have had it in my head that it was an and not an or situation.

That's the whole idea of 433.2.2(i), that the conductors would be protected against fault current.

It's only to guide you through the regulations and remind you to look at section 434. 433 is only about overload, so as a studious electrician you should be looking at how your installation will need protect against fault current also.

 

[GaryMo]

again though, sub paragraph (i) and (ii) only come into effect IF the cable has no branches OR outlets for current using equipment.. which a SOCKET is..
it has no internal fusing to it so you cannot rely on the fuse of whatever is plugged in as you don't KNOW for certain that there WILL be a fuse there at that point..

If that was the intention of the regulations then unfused spurs (sockets) wouldn't be allowed to be connected to a ring final protected by a 30/32A protective device (433.1.5).

Just another thought outside of the box!

 

[mfarrow]

again though, sub paragraph (i) and (ii) only come into effect IF the cable has no branches OR outlets for current using equipment.. which a SOCKET is..

The regulation talks about the length of cable between a reduction in cable size and a protective device. If there's no protective device (i.e. we haven't plugged anything in) how's that covered? (A genuine question by the way).

it has no internal fusing to it so you cannot rely on the fuse of whatever is plugged in as you don't KNOW for certain that there WILL be a fuse there at that point..

Too true, and having thought about it, there may be an unfused splitter on our single socket outlet.

So it looks like we've managed to limit ourselves to a humble FCU, or those fancy 3-way sockets with a fuse built in.

 

[NotHimAgain]

There is no requirement to accomodate the misuse of BS 1363 accessories - read 120.1 - last three words.

BS 1363 Socket outlets are intended to be used with fused plugs - they are not intended to be used without them - that would be a misuse and there is no requirement to protect against it.

 

[ColJack]

see the post above yours re: unfused splitters..

our local chippie has a double socket with 2 of these in it to plug in a fridge, a banmarie ( the pot thing they keep the musshy peas and curry sauce in ), the telly and a kebab cooker..

while these are not exactly breaking the bank with regard to current, there is the possibility there of plugging 4 things in at least...

another place I go to has a tea urn and an electric fire plugged into one of these splitters as the other socket has the computer extension lead plugged into it..

 

[GaryMo]

So it looks like we've managed to limit ourselves to a humble FCU, or those fancy 3-way sockets with a fuse built in.

Until you think about why 433.1.5 allows unfused spurs (sockets) to be connected to a 30/32A protective device.
You've already agreed there's no difference there being an extra couple of conductors in the same terminal.

 

[GaryMo]

ColJack, how is it any different to plugging the 'unfused splitters' into a socket that's been spurred off a ring final?

Same outcome in my book.

 

[ColJack]

it's not which is what prompted my original question..
why is it ok to have a spur from a ring but not a radial on it's own? it's the same thing but the regs dissalow it but then make an exception that does allow it... contradicting itself again..

 

[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.

 

[NotHimAgain]

Unfused splitters are not BS 1363 accessories.

The problem with all of this is that if you make a regulation unnecessarily proscriptive because of what someone might do, you end up reducing the potential benefits to all.

This particular example is not a good one as it is difficult to see why you would want to take advantage of 433.2.2 (i) in this instance. You could easily replace the mcb with a 20A or 16A device for about £3.50. There will be situations where leaving the 32A mcb in might be a good idea, but these are more likely to be in the industrial or commercial areas.

I know of only one regulation that actually attempts to accommodate misuse. It took JPEL/64 27 years to get round to including it in BS 7671 – now which one do you think it is .

 

[ColJack]

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....

 

[GaryMo]

This particular example is not a good one as it is difficult to see why you would want to take advantage of 433.2.2 (i) in this instance. You could easily replace the mcb with a 20A or 16A device for about £3.50.

I'm sure the majority of us would do exactly that - change the MCB for a 20A device.
It's more thought provoking than anything else, especially if you were to come across this scenerio which carrying out a PIR.