Design 32a 4mm radial

[Big daddy B]

Good morning I wonder if I could have some confirmation in regards to a radial circuit.

I have been showing apprentices different methods if wiring ring and radial circuits.

I wish to continue this next week.
I can not see any regulation not permitting the drawing enclosed, I would just like to confirm if it is installed on a 32a mcb with rcd protection and uses 4mm throughout, in my mind this would operate the same as if you ran a cable from main consumer unit to secondary (e.g garage) using an adequate power supply and cable and then allocating circuits.

Your assistance would be appreciated!
Kind regards
Paul

 

[DefyG]

The wires are bunched at the MCB which isn't the way you'd do it

Looks to me like only one cable emerging from the MCB then split later on?

 

[Mikegh]

Looks to me like only one cable emerging from the MCB then split later on?

Sorry ya you're right

 

[Pete999]

Not a standard circuit, no description of this method in BS 7671, S personally I wouldn't install it this way.

 

[pc1966]

Looks effectively like a 'lollipop' arrangement!
Which not everyone likes but is deemed acceptable these days providing usual design criteria is met!

I though the lollipop was a RFC fed from a sort of sub-main cable like an existing cooker supply that was repurposed? (Or sometimes a deliberate feed & isolator for things like school laboratories, etc)

 

[pc1966]

It is more of a tree circuit, with a feed "trunk" and branches to each of the sockets.

Personally I would prefer a multi-socket radial to be all in-line as then a check on the last socket verifies all continuity (rather like end-end on RFC).

A quick check in OSG Table 7.1(ii) as CCC met for clipped direct for feeder but not otherwise, and marginal for other cases on the branches (e.g. max demand for double sockets would be fine for all but 1010/103 method)

 

[telectrix]

horrible way to do it. more joints than Sainsbury's. and 2 lots of 7 conductors in a terminal. wagos only go upto 5. better direct to first socket then daisy chain 1-2-3-4-5-6.

 

[Zerax]

Generally... I'd always stick to a standard circuit and only depart from that if there are VERY good reasons not to. You may have very good reasons... but you haven't told us yet.

 

[telectrix]

Generally... I'd always stick to a standard circuit and only depart from that if there are VERY good reasons not to. You may have very good reasons... but you haven't told us yet.

maybe he's ROMAN....... What have the Romans ever done for us?

 

[telectrix]

or do i mean Romulans. easily confused when you get to my age.

 

[DefyG]

I don't think Big Daddy's drawing has helped as it implies terminations are outside the sockets but could easily be inside as per my drawing but personally I would take the feed cable to one end ( as dotted line) for a more conventional radial circuit.
Of course as we all know, in practice it is not always possible to wire it as shown on drawings.

 

[timhoward]

Of course as we all know, in practice it is not always possible to wire it as shown on drawings.

Agreed, the initial post saying this was a demo for apprentices is actually my main concern as I’d have thought they would be better off starting out with clear thoughts about more typical circuits, and built on that with understanding of overload and fault protection (encompassing selecting ocpd, installation methods, ccc etc) so they can assess anything quirky from first principles.
If this was a classroom exercise to discuss the regs then fair enough.

 

[Zerax]

Agreed, the initial post saying this was a demo for apprentices is actually my main concern as I’d have thought they would be better off starting out with clear thoughts about more typical circuits, and built on that with understanding of overload and fault protection (encompassing selecting ocpd, installation methods, ccc etc) so they can assess anything quirky from first principles.

Oh... I'd assumed that they were kitchen fitting apprentices ?

 

[timhoward]

Oh... I'd assumed that they were kitchen fitting apprentices ?

You may well be right, in which case even more reason to stick to Appendix 15 circuits!