Spur on ring main.

[davecooper]

"Nothing like proper planning, and having as a pervasive influence the concepts of "just in case...", and "but what if...", is there".

Very true. I was occupied more with other aspects of the room than future proofing the electrics. Lesson learned though.

 

[EFLImpudence]

Wouldn't an FCU still be needed?

Yes, one would still be a spur from a spur......

It depends. Does informative Appendix 15 show all there is?
Don't forget - talking about 5A sockets.

433.3.1(ii)

 

[ban-all-sheds]

Don't forget - talking about 5A sockets on a ring final. Please show me where the regulations permit such accessories to be supplied through a circuit with a 32A OPD and 2.5mm² cable installed as a ring.

 

[EFLImpudence]

If you maintain that 433.1.204 permits only BS1363 accessories to be supplied through a ring final then I cannot and we will have to disagree.

If you accept that it does not then it is nowhere prohibited (it is unlikely to be anywhere separately stated as allowed) and therefore allowed by 433.3.1(ii).

Also the items are on a spur and, while supplied through the ring main, no different than being on a 4mm² 32A OPD radial final with a 2.5mm² branch/spur therefore it must be considered that it is 'safe' within the constraints of the general regulations and knowledgeable design and so compliant with them and Part P?

 

[Spark123]

Unless you can find a regulation which says no.
You can have two accessories - a double socket.

You know it makes sense.

A double socket is a single accessory.

 

[EFLImpudence]

Yes, fair enough but the same result and technically inferior to two singles.

The rule, if it is one, makes no sense.

 

[Spark123]

It was a lot more clear in earlier versions of the regs, the 17th edn has been tinkered about with too much! From what I remember the 16th edn only allowed a maximum of the same amount of unfused spurs as there were sockets etc on the ring and they were only to supply one accessory. It seems to have been bunged into the appendixes as information in the 17th edn.

The reason I behind allowing a double socket is that in a double socket in the same location you are not as likely to have two 3kw heaters plugged in. Two single sockets in different rooms and the likelyhood increases.

 

[EFLImpudence]

It was a lot more clear in earlier versions of the regs,

You say clear - but that only holds true if there is a good reason for them.

the 17th edn has been tinkered about with too much! From what I remember the 16th edn only allowed a maximum of the same amount of unfused spurs as there were sockets etc on the ring and they were only to supply one accessory.

...and what justification was there for stating that?
There are bungalows of that time with all the sockets on spurs and none on the ring.

It seems to have been bunged into the appendixes as information in the 17th edn.

...and that is not exhaustive.

The reason I behind allowing a double socket is that in a double socket in the same location you are not as likely to have two 3kw heaters plugged in. Two single sockets in different rooms and the likelyhood increases.

That still won't overload the cable.


Perhaps the regulations have been 'revised' because they realised they were no good reasons for them.

There is no point having unjustified regulations.

 

[ban-all-sheds]

If you maintain that 433.1.204 permits only BS1363 accessories to be supplied through a ring final then I cannot and we will have to disagree.

Well nowhere does it say that other accessories may be supplied through one.

If you accept that it does not then it is nowhere prohibited (it is unlikely to be anywhere separately stated as allowed) and therefore allowed by 433.3.1(ii).

It's unfair of you to rely on a regulation hidden by my coat. Give it to me right now.

 

[EFLImpudence]

If you maintain that 433.1.204 permits only BS1363 accessories to be supplied through a ring final then I cannot and we will have to disagree.

Well nowhere does it say that other accessories may be supplied through one.

It does not say they may not; nor does it say they may be supplied by a radial.

If you accept that it does not then it is nowhere prohibited (it is unlikely to be anywhere separately stated as allowed) and therefore allowed by 433.3.1(ii).

It's unfair of you to rely on a regulation hidden by my coat. Give it to me right now.

I feel I've missed a joke.

You were saying that my suggestion of two 5A sockets on the spur would only be compliant if an FCU were installed.
I was saying that omission of overload protection subject to 433.3.1(ii) would be satisfactory.

This, of course, does not take into account that there may be two 5A (or less) fuses in the plugs - so protected anyway.




Ah - double quotes have come back. Thank you.

 

[Taylortwocities]

This, of course, does not take into account that there may be two 5A (or less) fuses in the plugs

MK do make a fused 5A plug, the 641, but it is not common. All of the 5A plugs I have installed or have seen in use in houses have been unfused and rely on the circuit (usually a 5 or 6A fused lighting circuit). to provide the protection.

 

[Echo the husky]

What about years ago where several 5A sockets would be wired to a 15A fuse? Unfused plugs there too.

 

[PBC_1966]

15A was the maximum protection permitted for radials feeding 5A sockets. And for years, the regs. specified an assumed demand of 5A on a 5A socket, thereby permitting only three 5A sockets on a 15A circuit, although in practice many more were often installed. But both then and now, if you want a 5A socket on a 30/32A ring, then it would need an FCU.

 

[PBC_1966]

MK do make a fused 5A plug, the 641, but it is not common.

And it takes BS646 fuses, which are not exactly a common item in the local hardware store or supermarket these days.