Hi all,

I am going to install an external porch light above my front door. there is nothing there currently. There is a 3 gang switch on the wall next to the front door I will swap out for a 4 gang.

Because I am on a very tight budget I want to run the cabling and fit the light myself, I want to get the sparky in just to wire up the switch, and ill be replacing the 3 gang switch with a 4 gang wifi smart switch which needs neutral. Reason I am asking here is, I don't want any surprises when they get here I am hoping its just a 20 minute job for them.

I took the current switch off to have a look at what was going on behind it, it confused me a bit -

- its 3 gang yet I had 5x 3 core cables coming in - everything was connected somewhere, I don't see any pigtails/jumpers, does that mean all 3 lights have their own supply?

- I had to turn off 2 breakers before the switch went dead, one of the lights on that 3 gang (middle one) can also be controlled by another switch in the garage, could that be the reason for the 2nd breaker needing to be turned off?

I have attached pics, I know its impossible to trace from a picture but Im just hoping this isn't some very obscure wiring method that will be difficult repeat. the wifi switch is very simple, L-in, N-in, L1-4 out

pics of current switch -



thanks!!!

 

No. One breaker powers one load (lamp) and the other breaker powers 2 loads (lamps) controlled via 3 gang switch. A simple on/off switch can have 2 cables in the electrical box so 3 switches with 5 cables is not an unusual configuration. You will have to determine which of the 5 cables provides voltage directly from a breaker and use this wire to connect to the new switch. A new cable must be run from the 4 switch box to the outside light location. In the 4 switch box connect the new cable black wire to the other connection on the new switch. Connect the new cable white wire to the white wire in the cable supplying voltage to the new switch. Connect new cable black and white wires to the new outside light. Ground wires should be extended as well.The insulation color of the wires/cables in the photo is unusual. Where are you located?

 

Because of the high number of wires you have working in that box already using pigtails to add the conductor you need might be helpful.

 

The switches and the use of the terms sparky and fit, suggest the OP is possibly in the UK or Australia. Voltages are probably 230V and wiring schemes and the wire colors are different.

 

Yes.... the member is from down under.
Very interesting wiring.
Sliding red tubing over a green wire wouldn't fly here..... it may not be proper there either.

 

Hi all, I appreciate your replies, and yes you are correct I am from the down under down under - New Zealand

My concern then, if I have two feeds coming from two breakers, I assume you cant just twist those together and put them into my single line in on the new switch - I suspect that would liven both circuits and render the breakers useless?

On further investigation, actually both the top and middle switch are dual switched lights.

 

Tying 2 breaker feeds together is illegal and dangerous. Don't do it!!!!! Somewhere a common wire could carry a current twice its rated capacity due to being sourced by two breakers. Since the breaker capacity is not reached, the breaker doesn't trip. The wire can get hot enough to start a fire. As stated in an earlier post, only power the new light with a cable hot wire whose voltage follows one of the two breakers feeding the 3 switch box with the other breaker on.

 

thanks and understood, but my question still remains - I am planning to remove that 3 gang switch and replace with the 4 gang smart switch, the 3 gang switch currently takes two hots from the breakers, the smart switch can only take 1. In that case is there anyway to do it?

new switch:

 

Use 2 smart switches. I would put the new light on the breaker with the smaller load.