Does this look right?

[EFLImpudence]

Perhaps the authors intended that the implied "only" would come before "through", thereby prohibiting the use of BS1363 accessories on radials?

As it does not include the word 'only', then it is not satisfactory to say it should be included in one place or another.

Does anyone think it was the intention of the authors to prohibit the use of JBs, DP switches, etc on RFCs?

As they are not prohibited on RFCs then I do not see how they could be prohibited on RFCs even if that were the intention.
There is no reason that they should not be allowed on RFCs because they are no different than RFCs as far as the accessory is concerned.

Where
R = Radial and
R = Ring

That's correct. It doesn't say that though, it says "may", which means it is permitted.

For all we know they could have meant "might".

 

[JohnW2]

That seemed to be your interpretation, ....

As I keep say, it's not 'my interpretation'. It is the interpretation which other people here always seem to have utilised whenever (quite often!) the issue has been discussed.

... although you then changed your mind and wrote that a 20A switch would be OK!

I've never changed my mind about whether it is, electrically speaking, 'OK' to have 20A switches and JBs connected to ring final circuits. What I have said is that, if all these other people are right in their interpretation of the regulation (as written), then I am personally very happy to be "totally irresponsible" and ignore such a daft regulation!

Kind Regards, John

 

[ban-all-sheds]

I was thinking about the word "only" in a cafe today. There was a notice stating "Only food bought in this cafe may be eaten in the cafe". Would the meaning be the same if "Only" were deleted?

No, but that rule is not an exemption to a wider one, so the analogy breaks.

Perhaps some would then interpret the notice to mean "Food bought in this cafe may only be eaten in the cafe"?

I'm sure they would. The world is full of people so unable to understand pretty simple English, (and pretty simple concepts) that they cannot grasp that there is a difference between, for example,

"Only buses may use the bus lane" and "Buses may only use the bus lane".

Perhaps the authors intended that the implied "only" would come before "through", thereby prohibiting the use of BS1363 accessories on radials?

Well clearly they could not have intended that.

Does anyone think it was the intention of the authors to prohibit the use of JBs, DP switches, etc on RFCs?

I don't.

But if anybody wants to agonise over what they "intended", a bit of logical reasoning should make everything clear.

Start by thinking about the nature of a ring final, and how it evolved, and what makes it safe. What makes it safe is the presence of fuses in plugs and FCUs, i.e. in the paths to each of the loads supplied by the circuit.

Is it not pretty clear that what they intended was that "points of use" should be through a BS 1363 accessory?

 

[JohnW2]

Start by thinking about the nature of a ring final, and how it evolved, and what makes it safe. What makes it safe is the presence of fuses in plugs and FCUs, i.e. in the paths to each of the loads supplied by the circuit.

I don't really understand that - in what way do the fuses in (potentially very many) plugs and FCUs protect 'the circuit'? The 'dispensation' regarding ring finals is that cable with a CCC of 20A may be protected by a 30/32A OPD, and I don't see how plug/FCU fuses make the (ring final circuit) cable any safer.

Put another way, I don't see that the cable of a 30/32A ring final would be any less 'safe' if it 'supplied', say, 32A sockets - since, again, it's the circuit's OPD which is protecting the cable.

Kind Regards, John

 

[John D v2.0]

it's the circuit's OPD which is protecting the cable.

Except the bit closest to the cu at each end which is protected by the fact that hopefully not too much of the load is there.

 

[JohnW2]

Except the bit closest to the cu at each end which is protected by the fact that hopefully not too much of the load is there.

It's not really "except". It's still the OPD which is 'protecting' that part of the cable, even if it doesn't provide adequate protection if too high a proportion of the load is close to one end of the ring.

In any event, my point was that whatever is protecting the cable, including the bits close to the CU, it is certainly not the fuses in the plugs/FCUs, the total 'rating' of which could theoretically be 200A or more!

Kind Regards, John

 

[stillp]

there is a difference between, for example,

"Only buses may use the bus lane" and "Buses may only use the bus lane".

Yes, but what about "Buses may use the bus lane"?

 

[stillp]

For all we know they could have meant "might".

Not if they have attended any of the "Drafting Standards" courses, or even just read the rules for drafting (BS0).

 

[ban-all-sheds]

I don't really understand that - in what way do the fuses in (potentially very many) plugs and FCUs protect 'the circuit'? The 'dispensation' regarding ring finals is that cable with a CCC of 20A may be protected by a 30/32A OPD, and I don't see how plug/FCU fuses make the (ring final circuit) cable any safer.

My turn to explain badly.

You cannot connect a load of more than 3kW to any point on the ring.

 

[ban-all-sheds]

Yes, but what about "Buses may use the bus lane"?

It means that it is not compulsory for buses to use the bus lane.

 

[stillp]

To me it means that buses are permitted to use the bus lane. Not quite the same thing.

 

[stillp]

Extract from BS0:

H.4 Permission
The auxiliary verb “may” should be used to indicate a course of action permissible within the stated limits of the document. Do not use “possible” or “impossible” in this context. Do not use “can” instead of “may” in this context. Phrases such as “may require”, “may be applicable”, “may be regarded” are incorrect: the correct wording is “might require”, “might be applicable”, “can be regarded” (see H.5).
NOTE “May” signifies permission expressed by the document, whereas “can” refers to the ability of a user of the document or to a possibility open to him/her

 

[ban-all-sheds]

To me it means that buses are permitted to use the bus lane. Not quite the same thing.

Buses may use the bus lane. If you understood what it meant, why did you ask 'what about "Buses may use the bus lane"'?

 

[EFLImpudence]

In all the explanations, I've forgotten who is saying 20A switches are allowed on ring circuits and who is saying they are not (I'm sure some have changed their minds).

There is not much point saying "Buses may use the bus lane" as it goes without saying and does not actually preclude other vehicles.
Such a regulation or sign would not be made and it is obviously recognised that it is better to say "Only buses (taxis and cycles) may ...", which IS what the sign shows, or "Vehicles other than buses (taxis and cycles) may not use ..." .

Therefore saying "Accessories to BS1363 may be supplied through a ring final circuit, ... , protected by a 30 A or 32 A protective device ..." is equally non-restrictive. Unless anything is exeplicitly prohibited, then so may they.

Similarly, "Accessories to BS1363 may be supplied through a radial final circuit, ... , protected by a 30 A or 32 A protective device ..." is as self-evident and non-restrictive yet in this case, because there is no such unnecessary ambiguous regulation there seems to be no dispute that other things are also allowed.

 

[stillp]

There is not much point saying "Buses may use the bus lane" as it goes without saying and does not actually preclude other vehicles.

Quite.

Therefore saying "Accessories to BS1363 may be supplied through a ring final circuit, ... , protected by a 30 A or 32 A protective device ..." is equally non-restrictive. Unless anything is exeplicitly prohibited, then so may they.

Again, quite.