Any reason I cannot use the conventional multi-way switching method if its convenient ? (Where the live and switched are connected to the switch commons). I need 3-way switching, and the way it works out, supplying the line at the end near the first switch, feeding an intermediate switch and then taking the live from the final switch to the 3 lights to be controlled together, results in reduced wiring length. I also need a particular switch Very much not loop-in ! If I want to use 3 core and earth with one core as neutral, is it OK to sleave the ends of the black or grey to indicate neutral ? I can run neutral alongside to avoid the induction loop problem. Thanks, Simon.
Yes, because in your 3+e cable you will have 2 strappers and N back from the lights. Which is the same as 2 strappers and Switched Live back to the lights
Surely he will need 4 cores plus earth between the first and last switch, if he has a 2 way switch circuit (intermediate third switch irrelevant), when the feed is one end of the 2 way, and the load is the other?
How would the cables normally be physically routed from one switch to the next? One wouldn't necessarily always be able to take a direct horizontal route, so then one would go vertically up, along above the ceiling, then down again, and so on [or possibly under floor instead of above ceiling].
Would you:
(A) Just route the 3+e cable as though the route were horizontal, which if the horizontal run is actually in the ceiling would mean that you have *two* 3+e cables going vertically from the ceiling to the middle switch (one coming from the previous switch, the other going to the next) [or in the case of the end switches this could be optimised to one 3+e plus one 2+e], or would you:
(B) Route 3+e between junction boxes in the ceiling and then just have a single 4+e cable going down to the middle switch [or a single 3+e in the case of the end switches]?
I can't really think of any case where it would be easier to feed the live in one end of a two or multi-way circuit and take the switch return out of the other. Much more sanitary to run the two way circuit in triple and earth and treat one of the switches as an 'ordinary' one with the switch drop pair to it.
Indeed. Plus when first fixing you really do not want to be preparing a job that needs junction boxes. Junction boxes are usually only used for repairs and alterations to circuits.
Really? Would you not run (at least) the wall verticals in conduit (if not the ceiling horizontals as well, and is it not normal practice to have junction boxes where conduits meet?
Why? It's no more mad than the standard way of wiring up ceiling roses to a single on/off switch, where the cable from the switch has the effect of "bringing" the switch terminals closer to the rest of the circuit.
But it *is* like the diagram, at least schematically speaking. The physical layout variation is fairly minor. There's no real difference between the following two versions, except that V2 only has 5 cores running vertically, whereas V1 has eight (of which 2 are earths, so one is unnecessary, and 2 are neutral both of which are unnecessary).
Version 2: L1 ---------------------+ +------------- to next switch L2 ------------------+ | | +---------- E ----------------O--+--+---+--+---------- N ----------------+--+--+---+--+---------- | | | | | | | | | | | | o o | | | \ / | | | X | | | / \ | | +--o o--+ | +-------O
But 5-core cable is nonetheless a fairly standard product. It's just that because there's less call for it, one is less likely to happen to have some lying around.
I was thinking that it would make for a less crowded vertical conduit to have one 5-core than two 4-core cables in it.
Normally yes, but it's not too difficult to think of a situation where it would save a cable run.
Eg from the CU to a switch at the back door, up to a switch at the bedroom window on the floor above, up to the second floor bedroom if it's a tall house, then out to a floodlight under the soffit. Enables anyone at the back of the house to keep an eye on the garden, and saves quite a long run of cable.
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