Does this setup contravene any regs or is it ok?

[johnduffell]

Why then could a lollipop layout be against regs if it is not designed to be a ring final and as long as the OCPD is the correct rating for the cable.

Well true, but i was meaning a 4mm "stick" with a 2.5mm loop all on a 32A mcb. If it were all 4mm or all on a 20A mcb the would be no point making it a lollipop

 

[SparkyChick]

Fascinating thread!

I quite like them as it gives you the chance to exercise your interpretation of the regs and get other opinions, regardless of whether they change your views or not.

It's one of the things I miss from my old job, the ability to quickly bounce ideas around and discuss them. Working solo isn't conducive to it... well, it's not if you don't want to end up in a straight jacket

So if they were indeed two circuits by design but we can change that by connecting them together at the CU, can we then lump three or four or even more to one breaker, loads considered?

I would say theoretically yes on the proviso that they are being moved to a breaker of the same rating as their original design or less. But loading aside there are other factors to consider like the ability to safely terminate the cables at the DB. There will be a point where it's just not physically possible to do it safely without say using a much larger cable and terminating the individual cables in a junction box.

Also if you had a long run of say 6.0mm SWA on a 20a OCPD and it was drawing 11a, and you had another circuit on a 20a which was 2.5mm T&E and drawing 7a could these be lumped together as one circuit even though they are of different sizes and even types? What would go on the certificate in respect of cable size?

In their own right, both cables would be adequately protected by a 20A OCPD, and the total combined load (assuming that is the maximum you've stated) would not result in nuisance tripping due to unintentional overload.

So yes, theoretically they could be combined. I'd record the difference in cable size by stating MIXED in the size columns and then expressing that on a continuation page. Same as I would for any circuit with mixed conductor sizes. The lollipop being a fine example - not that I've ever done this.

And of course providing due regard was given to the other parts of the regulations regarding division of the installation (i.e. minimise risks, inconvenience etc.).

However, would I do either of these things? I'm not sure. I might at a pinch (as an example, the situation where you need another breaker and cost is a major factor) but ordinarily I doubt I would.

Where does this end?

Well quite, I think it's another case of what the regs allow vs. what's widely accepted as good practice. Do I like seeing four conductors in an MCB... not really, is it strictly against the regs... probably not providing the other provisions of the regulations are catered for (such as overload protection, division of circuits etc.).

In this case, I can see the logic behind the OPs reason for doing it, would I have done the same? Probably not. Do I think it's acceptable? Well clearly yes I do, I just don't think it's good practice and I would probably have just left it as it was.

I thought you'd pick that one! So at the origin of the installation, is the 'point of supply' the incoming cables connect to the head, the main OCPD, if so which side of it, or the point at which the tail connects to the OCPD? It doesn't say so again you cannot go definitive on that.

I'm just not trying to overthink it too much. A cable doesn't supply electricity, it carries it, so in this case I consider the source of power to be the protective device as the origin.

Why? I fundamentally disagree with this. I believe that it is absolutely the cabling that defines the circuit. Are you saying that a breaker with no cable connected is still a circuit? We are getting down the semantics of what the definition is and I think this is where you and I differ.

No, I would consider a breaker with no cable connected as a spare way.

The regs state specifically that this is allowed from a ring final circuit and so this is also a red herring.

Do they though? The only section that gives any definitive guidance about the topology of a ring circuit is 433.1.204, and it only specifies the topology in terms of acceptable cable loading.

The only place I've been able to find a statement to the effect it's allowed is in the OSG and it doesn't reference a regulation to back it up.

So why wouldn't you do it then?

Because I don't consider it to be good practice, plain and simple. Regardless of whether I consider it to be allowed by the regulations, it doesn't feel like it's something we should be indulging in at every opportunity

Finally, if you are correct and I am not, then what is the meaning of 314.4?

It basically requires that each final circuit is capable of being isolated completely from a single point. I can't say much more than that without saying pretty much what it says.

 

[Deleted member 26818]

Information regarding the origin of final circuits can be found in Appendix 15.

 

[markythesparky]

I’m sorry Spin, I cannot see the word ‘origin’ in App15 at all.

 

[Michael J]

Sorry guys I am new to this having spent 40 years in Southern Africa.What does OP & lollipop mean?

 

[SparkyChick]

OP normally means original post or original poster.

Lollipop in this context is a circuit that starts as a single cable that supplies a ring final circuit. Useful if the ring final circuit is quite a distance from the distribution board (consumer unit).

They aren't that common (at least not in my experience) but they are allowed under the regulations.

 

[johnduffell]

Lollipop... aren't that common (at least not in my experience) but they are allowed under the regulations.

I wasn'sure if we had resolved that point, assuming we want to use 32a mcb and 2.5mm in the ring part.
"A final circuit arranged in the form of a ring and connected to a single point of supply"
So i would class the stem of the lollipop to be part of the final circuit, but i wouldn't consider it to be arranged as a ring. Also the point of supply of a circuit is the ocpd, not a point elsewhere on the circuit.

I do agree it's perfectly safe though!

 

[SparkyChick]

Let's clarify something... I was putting forward definitions in response to a query regarding the meaning of OP and lollipop.

So as definitions go, I'd say they are pretty accurate, so which parts don't you agree with and if you disagree, provide alternative definitions for the person who asked the question.

 

[johnduffell]

@SparkyChick maybe i didn't phrase it well, but i didn't have any objection to your definitions which were fine.
You also mentioned in your post that it is within the regs, which was the part i tried to quote and respond to.
It looks like the disagree rating came from @markythesparky who hasn't yet explained his view point.
As you can see i did provide an alternative which is that they may not comply with the regs, together with a possible justification for people to comment on.

 

[DPG]

I'm also interested in why markysparky disagreed with sparkychick's post re lollipop circuits.

 

[Deleted member 26818]

I’m sorry Spin, I cannot see the word ‘origin’ in App15 at all.

No the word ‘origin’ is not found in Appendix 15, though the word ‘start’ which is a synonym of ‘origin’ can be found.

 

[Deleted member 26818]

An OCPD cannot be the origin of a circuit, because BS7671 allows OCPDs to be omitted and also allows them to be positioned along the run of a conductor.

 

[static zap]

Sorry guys I am new to this having spent 40 years in Southern Africa.What does OP & lollipop mean?

Think of shape of a Lolipop
- Thick stick (single thick cable at cu)
--Circular -Ring on end of it .
(to be able to do any maintenance of ring -need access to this -JB)
..real point of origin of ring ..where any testing needs to be done ..

 

[DPG]

Disagree - of course an OCPD can be the origin of a circuit.

 

[MFS Electrical]

I like an assessor who knows his stuff.

There is, however, a difference between an assessor who knows his stuff and one who is just picking up on something for the sake of it. No regs breached technically compliant with the regs could be better but as the point has been raised earlier JB right up before the CU would make it the same circuit so why not from the same MCB?

 

[Deleted member 26818]

Disagree - of course an OCPD can be the origin of a circuit.

Ok where’s the OCPD at the origin of an installation?

 

[Ian1981]

A simple lighting circuit that we can all comprehend for clarity starts from the origin and is protected via its own OCPD and distributes out till the furthest point.
If a circuit didn’t start from the OCPD then you wouldn’t have separate circuits that are isolated by their own OCPD

 

[MFS Electrical]

Yes I know all about circuitry and tracing circuits what about three phase boards if for some reason someone connected one of the two cables into a breaker
on a different phase? We are not talking simple domestics now.

I fail to see the problem then as they would be two separate circuits again... but it’s a little beside the point as this was in a domestic setting.

 

[Deleted member 26818]

A simple lighting circuit that we can all comprehend for clarity starts from the origin and is protected via its own OCPD and distributes out till the furthest point.
If a circuit didn’t start from the OCPD then you wouldn’t have separate circuits

Well an FCU contains an OCPD (Fuse).
If I use an FCU to spur off from a circuit, does the fact that there is an OCPD at the origin of the spur, make the spur a separate circuit?

 

[MFS Electrical]

I’m afraid I agree with Stroma. The regs may not be written in the clearest way to avoid confusion or prevarication, but the intention of the regulation in my opinion is clear.

Just a thought, if the OP did that with two lighting circuits to free up some space, why not do it with some other circuits including Rings (loads accepted)?

My understanding of it is a lighting Circuit and then another single lighting point has been added in the loft sounds awfully like a spur taken from an OCPD of a lighting circuit to me