Width of cable safe-zones in walls created by sockets

[sparkwright]

If you must have a ring, the long blue 'return' cable is a poor design, a far better option is to connect the accessories alternately, so the cable left to right connects to every other accessory, and the cable from right to left connects to the others.
Both cables can then be in line with everything, so that they are also in the appropriate zone.

I would say doing that could make future fault finding a more awkward task.

 

[flameport]

future fault finding a more awkward task.

Probably does, but it ensures the load is distributed on the ring.
The other method results in all the load at one end, one leg takes most of the load and the other very little.

 

[JohnW2]

Probably does, but it ensures the load is distributed on the ring. The other method results in all the load at one end, one leg takes most of the load and the other very little.

Whilst (assuming that the start of the right->left 'return' cable in the OP's diagram is the centre of the ring) your method would clearly result in better balance, I think you are probably over-stating the potential problem (with what must be a very common arrangement)

Again assuming that the mid-point of the ring is as above, a fair number of the potential loads are quite close to the centre of the ring (hence a substantial proportion of their current would flow down the 'return cable' and, particularly if the run (of both cables) from the top left of the diagram to the CU is of appreciable length, it is quite possible that all of the loads would be sufficiently far from the end of the circuit that no cable would be overloaded even if (pretty unlikely) a full 32A was drawn through the sockets closest to the CU.

Kind Regards, John

 

[winston1]

I thought safe zones didn't go around corners.

Is that a FCU feeding the dishwasher socket? It shouldn't be as you don't need two fuses in line (the other being in the dishwasher plug). You really need a 20 amp DP switch.
EDIT. Same applies to the fridge of course.

 

[JohnW2]

I thought safe zones didn't go around corners.

They don't - which is why davelx pointed out that the OP would need some sort of accessory on the West wall for that lower horizontal cable.

Kind Regards, John

 

[sparkwright]

All seems like a lot of horizontally run cables.

Have you considered running some of the cables horizontally within 150mm from the ceiling, then running vertically down to the accessory?

May make life easier.

 

[Iggifer]

It's also going to be a big mess of cables crossing over each other as they go up/down for accessories. If they were all straight drops down it would be MUCH easier.

As has been said you can do this quite easily without damaging the ceiling. Get the plaster chopped off the wall for the drop, then make a neat hole where the wall plaster sits, wire, patch = no ceiling hole.

I'd be getting a row of boards up upstairs and doing it that way personally. The odd horizontal run often makes a lot of sense, but trying to do them all like it is going to give you a headache, I promise

 

[davelx]

I think he's explained it's only drawn like that for clarity.

Yes, I noticed that. But does he really have that return cable running back through all the back boxes and therefore visible to anyone removing an accessory to check the position of the cable runs?

 

[ban-all-sheds]

If there are base units and appliances all along the 3 walls, the cable could go on the surface of the walls behind them, and therefore no concealment problems, and run up, concealed, to each accessory.

 

[sparkwright]

Yes, I noticed that. But does he really have that return cable running back through all the back boxes and therefore visible to anyone removing an accessory to check the position of the cable runs?

Not sure, but he did ask if the cable zone applies to the 'width' of the back box, or the accessory, so MAYBE he is considering running the so-called 'return' cable just under or above the outside edge of the box.