Most economical way to wire 'staircase' switching

[DanDIY]

I have a large room which I have 2 doorways about 9m apart. I want switches next to both doorways.
There will be 3 'zones' of lights, therefore a 3 gang light switch at each doorway.

The three zones are roughly 1/3 of the way across the room each.

If this was a stairway I would use 3 core + earth, running my two strappers and neutral in the same cable.

In this situation it would seem a waste to have three lots of 3 core (therefore 3 neutrals) spanning 9m where I dont need it. I was planning on using 3 lots of 2 core T&E as the strappers.

From the incoming radial circuit I was going to run a single core live to the first switch set to feed it live. From the second switch set I was going to bring the switched lives back with 3 core to a junction box. Then single core and earth to the respective pendants.

Is it ok still to use single core and earth? I dont see much (any) mention of it....

 

[EFLImpudence]

If this was a stairway I would use 3 core + earth, running my two strappers and neutral in the same cable.

There is no neutral.
All three are lives.

There are different ways to do it depending on the routing but you will need a minimum of three two-core and earth between the switches so you may as well do it in the conventional way.

 

[DaftPunk]

You should run 3 core and earth used as the strappers and common to minimise the effects of RFI

 

[OwainDIYer]

That size room I'd try and put the lights on 2 different circuits / RCDs anyway.

Alternatives to running lots of mains cables are (a) low voltage / relay switching (b) wireless switches.

 

[flameport]

I was planning on using 3 lots of 2 core T&E as the strappers.

Could be done, or use 2x 3 core & earth, you can then use the same colour wires for each switch.

From the incoming radial circuit I was going to run a single core live to the first switch set to feed it live. From the second switch set I was going to bring the switched lives back with 3 core to a junction box. Then single core and earth to the respective pendants.

1C&E to the pendants is no use - they will all require a neutral so T&E would be more usual.
A junction box should be avoided if possible, and must be accessible if you insist on using one.

Is it ok still to use single core and earth? I dont see much (any) mention of it....

Single core is still available, although seldom used as there are few situations where it would be required. You may have to buy a whole roll of it, which would be a huge waste if only using a small section for a single circuit.

 

[ericmark]

You need 7 wires plus earth between the two sets of three switches it one switch is master to all lights. If one switch is master i.e. connected to light direct at the other end then you can borrow the line so reduces it to 6 wires. As to using 2 x 3+E or 3 x 2+E what is the question is what you will have left over at end of job rather than working out price per meter. Buying a role of 2+E and having extra run could mean less cable left on reel at the end. It would also mean counting chases in the wall even volt drop so there is no one answer fits all.

It is recommended that you don't borrow a line as this can produce mains hum in some equipment so I would run 7 wires plus earth.

 

[AndyPRK]

I assume you will be having fancy lights and not roses.

Therefore its usual to have neutrals at the switches.

I would therefore have the L&N coming into the 1st switch.

You could take all the light T&E's out the 2nd switch.

The minimum you would require between switches would be:

3C&E (for the neutral) and 1st light strappers
2C&E 2nd light strappers
2C&E 3rd light strappers

No junction boxes required, and hopefully not too many cables/wires at each switch.


Its likely some lights would be nearer to the other switch.
Therefore you could connect those to the 1st switch.
In which case 3C&E is required for those.

I think this option would be a head ache for someone afterwards, so better to just have longer cable runs to the lights

 

[333rocky333]

If this was a stairway I would use 3 core + earth, running my two strappers and neutral in the same cable.

There is no neutral.
All three are lives.

I read it as Two strapper lives And 1 Neutral and the plan was to use the third core just to get a neutral from one end to the other, or maybe leave unused, as he also talks of feeding one switch and taking the load from the other one, which as you know would only need two strappers

 

[EFLImpudence]

If this was a stairway I would use 3 core + earth, running my two strappers and neutral in the same cable.

There is no neutral.
All three are lives.

I read it as Two strapper lives And 1 Neutral and the plan was to use the third core just to get a neutral from one end to the other, or maybe leave unused, as he also talks of feeding one switch and taking the load from the other one, which as you know would only need two strappers

I read it as an error on the OP's part thinking one of the strappers was a neutral.

I don't understand why you think it would be necessary to get a neutral from one end to the other.


As I said, there are different ways to wire the three two-way switches but I think the conventional (convertion) method should be used.
As Andy said, an unusual method would lead to confusion in the future.

 

[DanDIY]

EFLImpudence wrote:
DanDIY wrote:
If this was a stairway I would use 3 core + earth, running my two strappers and neutral in the same cable.

There is no neutral.
All three are lives.



I read it as Two strapper lives And 1 Neutral and the plan was to use the third core just to get a neutral from one end to the other, or maybe leave unused, as he also talks of feeding one switch and taking the load from the other one, which as you know would only need two strappers

Read more: //www.diynot.com/forums/electr...ire-staircase-switching.406242/#ixzz36RPI623U

This is what I meant. I know that the strappers are both lives, but as some of the lights are closer to one end of the room than the other I was thinking of carrying the neutral through and save the runs back and forth from the rose to the switch.

Given the confusion that this has caused I think it is a good illustaration of what could happen if I use some weird and wonderful circuit, therefore I will stick with a 3off three core conversion circuits.