Does adding a spur from the MCB require Part P?
- Thread starter Seb101
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deleted - didn't read properly!
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deleted - didn't read properly!
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..only in Mold...
You obviously saw my recent posts before I deleted them. I had not looked at this thread before, and stupidly thought that 'page 2' was all rhere was!
Kind Regards, John
Thanks for the responses everyone.
perhaps I wasn’t clear but yes, I was expecting the chime box to have an AC/AC bell transformer in it, as it looks identical to every other chime box I’ve seen which did. Instead it had 4 C-cells in it, wired to the door bell button and the chime solenoid. Not something I’ve seen before but probably more common that I thought.
The plan is to drop a doorbell transformer in there instead as all the bell wiring can be reused, it’s just a question of how to get the mains supply to it.
Sounds like taking a spur from the MCB is fine because it’s not a new circuit. Obviously will be careful to ensure the whole CU is isolated before doing anything.
cheers!
perhaps I wasn’t clear but yes, I was expecting the chime box to have an AC/AC bell transformer in it, as it looks identical to every other chime box I’ve seen which did. Instead it had 4 C-cells in it, wired to the door bell button and the chime solenoid. Not something I’ve seen before but probably more common that I thought.
The plan is to drop a doorbell transformer in there instead as all the bell wiring can be reused, it’s just a question of how to get the mains supply to it.
Sounds like taking a spur from the MCB is fine because it’s not a new circuit. Obviously will be careful to ensure the whole CU is isolated before doing anything.
cheers!
Indeed.
In passing, what you are talking about would not normally be called 'a spur', since most people only use that term in relation to ring circuit (and perhaps also where a branch from a radial circuit has smaller cable than the rest of the circuit.
Domestic lighting circuits are nearly always 'radial' circuits (not rings) - and a radial circuit can (and often does) 'branch' at any point in the circuit - and that 'point' can be anywhere, even where the circuit originates at an MCB (or fuse, or whatever).
Kind Regards, John
All electrical work in a home should conform to the requirements of Part P of the Building Regulations
But Part P does not say what you think it does.
Requirement P1 in Part P is a single sentence, 28 words long.
There is no Requirement P2 or any other Requirements.
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All true.
However, as we all know, and very much aided and abetted by eric repeatedly perpetuating this misunderstanding, when people talk about 'requiring Part P' in this sort of context, they actually mean 'notifiable' - and, although the 28 words of Part P, per se, say nothing about notification, the Building Regs of which they are part obviously does impose the requirements for notification.
Kind Regards, John
Thanks. I was struggling for the right terminology, ‘branch’ is a better description!
While I would agree with what John has written, the definitions in the regulations state:
"Spur. A branch from a ring or radial final circuit."
There is no electrical definition of 'branch'.
"Spur. A branch from a ring or radial final circuit."
There is no electrical definition of 'branch'.
That is true - so, as you imply, the regs regard a branch from a radial as being a 'spur'.
However, as I said, I don't think many people use such terminology for a radial. In fact, it's generally impossible to do do, since if a radial 'branches' (with cables all of the same size), then it's impossible to define which of the two resulting cables is 'the circuit' and which is the 'spur'.
It is probably peculiar to me but, as I implied, I have personally adopted the convention of using "spur" to describe a branch from a radial which is of a smaller cable CSA than the 'main part' of the circuit (e.g. a 2.5mm² branch, supplying one socket, from a 4mm² radial). However, as said, that's probably just me, and I doubt whether many people would use "spur" even for that. However, I personally find it useful to indicate that it is a a branch of 'limited socket-supplying capability') and, in that case, it is also clear which is 'the circuit' and which is the 'spur'. This might be particularly relevant if anyone installed a 2.5mm² 'fused spur' (to supply multiple sockets) from a radial circuit (which I doubt they often do!).
Kind Regards, John
Yeah, in principle. The problem is that if the video camera
Not uncommon. Just make sure that the you use the 15 (or less) voltage option on the transformer. I assume that your door bell will be happy with 15v
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