Discuss two radials into an RCBO in the UK Electrical Forum area at ElectriciansForums.net
Sorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.The BG can fit onto a Din rail. Not sure if it fits a Wylex busbar, or any busbar.
"Can be fitted on DIN rail directly into the consumer unit."
Thx. Never looked in detail. The Wylex looks the business then. The Wylex's only protection is the main incomer fuse? mmmmSorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.
With these circuits merged do you have way free or two, as the BG SPD also needs an > B16 MCB .
(The Wylex module does connect to the bus bar and only needs one way total.)
Fixed that one for youPeople like a fridge on their own circuits so if another circuit is at fault the beer in the fridge is nottaken outgetting warm,
Some makers do not recommend an SPD has its own RCBO/MCB, as a dedicated MCB can be left off by mistake. An essential circuit will not be left off, so they recommend it is taken off one of these. They recommend the SPD is taken off an adjacent 32A RCBO/MCB. That may mean three wires into the terminal of an RCBO, which is against the regs as posted here.Sorry if we are at cross purposes, or I'm stating the obvious, but the BG has the earth connection at the bottom, and doesn't connect to the bus-bar at all.
With these circuits merged do you have way free or two, as the BG SPD also needs an > B16 MCB .
(The Wylex module does connect to the bus bar and only needs one way total.)
It is not the fact it may be left off. You need to contact the manufacturer as to whether the spd needs external circuit protection. If you are retro fitting one I suggest you provide external protection otherwise you are interfering with the manufacturers internal configuration which may well go against Regulations.Some makers do not recommend an SPD has its own RCBO/MCB, as a dedicated MCB can be left off by mistake. An essential circuit will not be left off, so they recommend it is taken off one of these. They recommend the SPD is taken off an adjacent 32A RCBO/MCB. That may mean three wires into the terminal of an RCBO, which is against the regs as posted here.
Surge Protection Devices sell various ones (Available at some CEF), and the answer I had from them at a trade show a while back is that because it's not on the busbar it is not necessary to 'match' the make of the switchgear for type testing requirements. They do specify a separate MCB though.The idea is to make a way for an SPD by joining two circuits. The SPD will be a single way unit. The BG SPD looks OK. Can it fit into a Wylex CU?
View attachment 86813
Splitting the ring and leaving both sections connected to the same MCB/RCBO doesn't break 314.4 in itself - it's just two radial circuits from the same source, but the breaker will have to be reduced from 32A to a maximum of 20A, and consideration made as to whether that is likely to be sufficient without experiencing overload. For those reasons, it's often preferable to split into two separate circuits.Out of interest, would your comment mean that 314.4 can never actually be broken if combining radial circuits?
Doesn't apply to fridges quite so much, because they have a light inside and are opened fairly frequently, but I always try to make sure a freezer is on the same circuit as something else important, such as the wi fi router or TV. That way, if the circuit has tripped out, it will be noticed fairly quickly.
Similarly, I always connect smoke alarms to the same circuit as the most frequently used lights.
It clearly does:Splitting the ring and leaving both sections connected to the same MCB/RCBO doesn't break 314.4 in itself -
Not necessarily. A final radial circuit can be wired as a tree with multiple branches, one or more of which branches could be connected to the same way, so it is still only one radial circuit.It clearly does:
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
It clearly says that one radial (final circuit) needs its own way.Not necessarily. A final radial circuit can be wired as a tree with multiple branches, one or more of which branches could be connected to the same way, so it is still only one radial circuit.
It's an argument as old as time, but my take is...It clearly says that one radial (final circuit) needs its own way.
Yes, as I can read and interpret English. It says final circuits must have their own way (mcb, RCBO).Doesn’t #40 answer your own question?
There is no ambiguity in 314.4. The final circuits must have own RCBO or MCB.It's an argument as old as time, but my take is...
The interpretation of 314.4 is all down to how you define a final circuit.
If the regulation was meant to mean a final circuit will consist of a single line conductor in the case of a radial and two line conductors in the case of a ring, then this is what they should have said.
In my mind a final circuit is exactly what a competent electrician had designed it to be, accounting for design characteristics and manufacturers instructions. Therefore, as spurs are permitted, where and how the electrician decides to make a spur is not restricted by 314.4.
but if you have 2 radials off 1 MCB, then those 2 radials combined are, by definition, 1 final circuit.There is no ambiguity in 314.4. The final circuits must have own RCBO or MCB.
A final circuit is any circuit whether it is a ring or radial, with any of them with branches, spurs, etc. It is clear in the writing of 314.4 they cannot be connected to one way.
Maybe you're confusing cables with circuits.There is no ambiguity in 314.4. The final circuits must have own RCBO or MCB.
A final circuit is any circuit whether it is a ring or radial, with any of them with branches, spurs, etc. It is clear in the writing of 314.4 they cannot be connected to one way.
You arguing a logical fallacy, an argument from authority.There is no ambiguity in 314.4. The final circuits must have own RCBO or MCB.
A final circuit is any circuit whether it is a ring or radial, with any of them with branches, spurs, etc. It is clear in the writing of 314.4 they cannot be connected to one way.
This is the crux of the matter. You ARE interpreting the wording incorrectly.Yes, as I can read and interpret English. It says final circuits must have their own way (mcb, RCBO).
The text:You arguing a logical fallacy, an argument from authority.
You claim there is no ambiguity where the constant debates on this subject clearly reveal otherwise.
Rather than state, as fact, "there is no ambiguity" you should say "I see no ambiguity" which is fine, its a personal opinion and one your entitled to.
If you could add a technical reason why this practice is unacceptable then fine but at the moment the argument seems to me to be "I don't like it and the regs say you can't do it".
I am confusing nothing.Maybe you're confusing cables with circuits.
A circuit can consist of more than one cable connected to the source.
I don't see the difference.When I originally mentioned this reg on this post, I said this was fine and happens a lot, there is one reg to be mindful of, and asked the question - "can the two legs be considered one circuit".
The last bit is key, as very often they can, but sometimes they can't legitimately be classed as one circuit due to ccc or ocpd requirements.
For example, at a recent EICR I found an unlabelled 30 amp rewireable fuse, testing showed it fed a sub main to a shed and apparently strangely two sockets in a utility room. Take front off board and find a 6mm and a 2.5mm live in the same fuseholder. One might logically guess the 2.5mm was a radial for the two sockets. In fact it was yet another radial for a boiler FCU. (the utility room sockets turned out to be a joint box off the 6mm)
In that situation I had no issue citing 314.4 as one reason it wasn't adequate, the ocpd wasn't suitable for the boiler circuit and the whole lot was downright confusing. Definitely two circuits in the same fuseholder.
But if the same OCPD is needed, the same CCC, and the total loading is suitable, it clearly becomes one circuit in my mind.
I wouldn't say incorrectly exactly just a little lacking in nuance.This is the crux of the matter. You ARE interpreting the wording incorrectly.
You're just shouting the same thing louder.The text:
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
What don't you understand about the clear English 314.4 is written in?
The crux of this lies in whether its acceptable to spur from the supply source of the final circuit to extend the circuit.The text:
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
What don't you understand about the clear English 314.4 is written in?
Reply to two radials into an RCBO in the UK Electrical Forum area at ElectriciansForums.net
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