Discuss Does this setup contravene any regs or is it ok? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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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)?
 
So, you believe this set up is a contravention of regulation 314.4 (I believe that's what the OP stated as being the reg that Mr. Assessor was citing as the reason this arrangement was non-compliant)... care to explain how it contravenes the regulation?
 
So, you believe this set up is a contravention of regulation 314.4 (I believe that's what the OP stated as being the reg that Mr. Assessor was citing as the reason this arrangement was non-compliant)... care to explain how it contravenes the regulation?

As I said, the wording is not perfect but it is obvious to me at least that the intention of the Reg is clear.

Would you do the same with other circuits in that board if the loads allowed? Rings?
 
So, the regulation itself....

314.4 Where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board. The wiring of each final circuit shall be electrically separate from that of every other final circuit, so as to prevent the indirect energizing of a final circuit intended to be isolated.

That's pretty straight forward.

On to the definitions...

Final circuit. A circuit connected directly to current-using equipment, or to a socket-outlet or socket-outlets or other
outlet points for the connection of such equipment.


That seems pretty straight forward to me. Lighting circuits IIRC so they fit the definition.

Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s).

Two legs of a radial circuit supplied by the same origin and protected by the same protective device.

To answer your question... have you never put two circuits of any kind together onto a single breaker as a temporary stop gap solution? I have, and would do it again in a heartbeat providing there is a suitable breaker available... by that, I'm not stupid enough to put a lighting circuit on a 16A breaker (although technically a lot of lighting circuits could handle that) or stick a ring final socket circuit on a 20A breaker onto a 32A breaker with another RFC because there is probably a very good reason the one is limited to 20A (installation methods maybe). So yes, I possibly would because then the two final circuits become one circuit (supplied by the same protective device from the same origin) and as such are still compliant with the regulations.

How is it non-compliant? What do you believe the intention of the regulation is? That's all I'm asking... expand on why you believe it is non-compliant. Your explanation might make me (and others) look at it in a different light, it might change our minds.
 
The wiring of each final circuit shall be electrically separate from that of every other final circuit, so as to prevent the indirect energizing of a final circuit intended to be isolated.

These are in fact two circuits and I will explain this later, and assuming this, these are not now electrically separate as they have been connected together.
This brings us to the definition of what a circuit is.

Final circuit. A circuit connected directly to current-using equipment, or to a socket-outlet or socket-outlets or other
outlet points for the connection of such equipment.

Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s).

This is where your argument gains ground and I have sympathy with it although consider this; when the OP designed the installation it is clear that he intended these to be two circuits. This is impossible to argue against. Assuming that you agree with that statement, then the definition above needs clarification. Or does it? What is the meaning of 'origin' in this case?' Are you relating the word origin to what we know as the 'origin of the installation', in which case you have some foundation. but if the word 'origin' in this case means the same piece of cable, then your argument does not stack up. These two circuits do not have the same origin they have two!

To answer your question... have you never put two circuits of any kind together onto a single breaker as a temporary stop gap solution? I have, and would do it again in a heartbeat providing there is a suitable breaker available...

You seem to be conflicted.
Yes I have ‘lumped’ two circuits together as ‘temporary stop gap solution’.
I did it as a temporary stop gap solution knowing that, in my view and yours presumably as you have inferred, it’s ok as a temporary fix. But if its ok as a temporary fix, by definition it isn't meant as a permanent solution. Therefore the man from Stroma is correct. It doesn’t comply with the intention of the regulation. It is electrically safe taking into consideration the anticipated loads on those circuits but is does not comply. My temporary fix was not left like it.

I'm not stupid enough to put a lighting circuit on a 16A breaker (although technically a lot of lighting circuits could handle that) or stick a ring final socket circuit on a 20A breaker onto a 32A breaker with another RFC because there is probably a very good reason the one is limited to 20A

Theres nothing wrong with having a lighting circuit on a 16a breaker as long as the cable is sufficient. I'm not sure what you mean by the ring on a 20a breaker though.

My question is would you wire two ring circuits into one 32a breaker allowing of course for the loads anticipated on those circuits and leave it like it permanently and sign a completion certificate saying that it fully complies with BS7671.
 
Personally, I would not have wired the lobby and the attic as one circuit. If I were to come across such an installation, I’d be wondering what the original installer was thinking of.

I would probably go with wiring the lobby in with the rest of the ground floor and lable the circuit as Ground Floor.
If there were a separate circuit for the stairs, I might consider wiring the lobby in with the stairs.

If I were to add attic lighting to an existing installation, I would most likely come off the upstairs lighting.

The origin of any final circuit is the DB/CU.
 
Some people are looking at this backwards. A circuit is not defined topologically(other then a ring). It doesn't matter how it branches and at what points, any collection of points arranged as a tree topologically can be a circuit.
If there's an ocpd and some wiring that forms a tree, then by definition that is a circuit. The ocpd defines the circuit. Doesn't matter if you combined 3 previous circuits into one ocpd, you've turned them into one circuit.
As hinted above, the only exception would be combining two rings into one. That wouldnt be a valid circuit as the whole circuit has to be arranged as a ring. However that would only be against the regs in the same way a lollipop would be, and could probably be a deviation.
 
Your argument is quite compelling because it's made me think about it again and I was starting to question my own view, but having just re-read the definitions and 314.4 I'm sticking to my guns and this is why.

These are in fact two circuits and I will explain this later, and assuming this, these are not now electrically separate as they have been connected together.

Fundamentally, yes they are two circuits... or more precisely, they were two circuits as they were originally designed, installed and connected to two different protective devices at the origin.

To address your question about the origin, since there is no definition of origin for a circuit, it seems sensible to base it on that of 'origin of the installation' i.e. the point of supply of electrical energy, which in this case is the protective device the circuit is connected to.

The definition of 'final circuit' is there to differentiate it from a distribution circuit and in this context is largely a red herring I believe.

The mere act of changing the origin of one of these circuits to that of the other means they become one circuit. It isn't the cabling that defines a circuit, it's the origin. The cable is not a point of supply of electrical energy for the circuit, the protective device it is connected to is.

Taking your argument that the cables are the origin to the extreme, you're saying you can't have a spur off a ring final circuit that originates at the device that protects the ring conductors because they aren't the same cables, which I think you'll agree is a nonsense.

You seem to be conflicted.

Not conflicted, just sensible.

Yes I have ‘lumped’ two circuits together as ‘temporary stop gap solution’.
I did it as a temporary stop gap solution knowing that, in my view and yours presumably as you have inferred, it’s ok as a temporary fix. But if its ok as a temporary fix, by definition it isn't meant as a permanent solution.

When you combine two circuits in this manner, there is a risk that the protective device will be overloaded as a result and thus subject to nuisance tripping under normal use because the installation was previously divided to minimise the chances of that happening.

Hence I would consider it a temporary solution to get the customer back on-line ASAP whilst a more permanent solution is implemented.

However, in the case of two lighting circuits, it's unlikely (based on the OPs description) the OCPD at the origin is going to be subjected to an overload when they are combined, so this is an acceptable thing to do.

Therefore the man from Stroma is correct. It doesn’t comply with the intention of the regulation. It is electrically safe taking into consideration the anticipated loads on those circuits but is does not comply. My temporary fix was not left like it.

Very different situations as outlined above, so I disagree. Mr. Stroma was incorrect.

Theres nothing wrong with having a lighting circuit on a 16a breaker as long as the cable is sufficient.

I think I said that :)

I'm not sure what you mean by the ring on a 20a breaker though.

Basically a ring final circuit on a 20A circuit breaker, most likely as a result of installation methods (cable in insulation for example). I've seen it a couple of times. Wired in 2.5/1.5mm but due to installation methods, a 32A breaker runs the risk of overloading the cable (thermal effects) so a 20A breaker has been deemed suitable.

My question is would you wire two ring circuits into one 32a breaker allowing of course for the loads anticipated on those circuits and leave it like it permanently and sign a completion certificate saying that it fully complies with BS7671.

Would I do it? No. But based on 433.1.204, providing the cabling complies, it's questionable whether it would contravene any regulations.
 
Fascinating thread!

Fundamentally, yes they are two circuits... or more precisely, they were two circuits as they were originally designed, installed and connected to two different protective devices at the origin.

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?
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? Where does this end?


To address your question about the origin, since there is no definition of origin for a circuit, it seems sensible to base it on that of 'origin of the installation' i.e. the point of supply of electrical energy, which in this case is the protective device the circuit is connected to.

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. You could argue that the tail's connection to the OCPD is the point of supply of electrical energy and to follow that argument, the cable feeding the lighting circuit is too.


The definition of 'final circuit' is there to differentiate it from a distribution circuit and in this context is largely a red herring I believe.

Agreed.


It isn't the cabling that defines a circuit, it's the origin. The cable is not a point of supply of electrical energy for the circuit, the protective device it is connected to is.

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.


Taking your argument that the cables are the origin to the extreme, you're saying you can't have a spur off a ring final circuit that originates at the device that protects the ring conductors because they aren't the same cables, which I think you'll agree is a nonsense.

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


Would I do it? No. But based on 433.1.204, providing the cabling complies, it's questionable whether it would contravene any regulations.

So why wouldn't you do it then?

Finally, if you are correct and I am not, then what is the meaning of 314.4?
 
It doesn't matter how it branches and at what points

However that would only be against the regs in the same way a lollipop would be, and could probably be a deviation.

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.
 
Either on here or elsewhere their was a spark, who also worked part time for fire brigade. He said of some of the sights he'd seen and the damage to human life he'd seen, and how working smoke alarms could have prevented it. Part of his thinking was smoke alarms on commonly used lighting circuit could have prevented it. It's a logic and approach I agreed with then, and still do now.

You can't help stupid though - if they pull smoke alarm heads off and throw them in the bin with no intention of repairing them, nothing we can do, whether separate circuit or on with the lighting.
 
Either on here or elsewhere their was a spark, who also worked part time for fire brigade. He said of some of the sights he'd seen and the damage to human life he'd seen, and how working smoke alarms could have prevented it. Part of his thinking was smoke alarms on commonly used lighting circuit could have prevented it. It's a logic and approach I agreed with then, and still do now.

You can't help stupid though - if they pull smoke alarm heads off and throw them in the bin with no intention of repairing them, nothing we can do, whether separate circuit or on with the lighting.

But I don't see why the smokes are better being fed with another circuit. Is it because people are not likely to switch of a lighting circuit if there smokes are beeping?
 
But I don't see why the smokes are better being fed with another circuit. Is it because people are not likely to switch of a lighting circuit if there smokes are beeping?
In a nutshell, yes.

Domestic Smoke alarm maintenance can be a bit of a losing battle, folk seem to think if they change batteries when it bleeps, the fact it says replace by NOV 2010 means bugger all.
 

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