Share the neutral

[moskovskiy82]

Currently have the lights in my home connected to Legrand relays (installed the switch box).
Decided to change them to mysensor nodes (also installed in the switch box).
Currently in the socket under the momentary switch i have L and N going to the lamp.

So after integrating mysensors in place the question is - how to connect the mometary buttons. Do i have to use 2 wires - one for N (GND) from arduino and one connected to the digital pin. Or i can use just one wire connected to the digital pin and the second connect to the N which is already in the socket?

[mfalkvidd]

@moskovskiy82 N is NOT gnd/earth. It carries AC power. So connecting the button to that will be very dangerous.

[moskovskiy82]

@mfalkvidd said:

@moskovskiy82 N is NOT gnd/earth. It carries AC power. So connecting the button to that will be very dangerous.

As i am running short of wires. What if the push button will connect one end to the digital pin on arduino and the second one go to the mains ground (PE). Wonder if that will work and will not cause the circuit breaker to activate. Any ideas on this?

[moskovskiy82]

Well it works with low stability. Only half of the pressings get activated. Maybe something to do with debounce settings?
Currently have them at debouncer[i].interval(5);

[dbemowsk]

By switch box I am assuming that you are talking the box on the wall for your light switch. As @mfalkvidd said, N is not GND/earth. This is the return path for the AC. Even though in your main breaker panel there is probably a connection from the (N)eutral bar to the Ground/earth bar, the neutral wire should NEVER be used as a ground. The incoming power to your wall box should have a ground wire unless it is an older house in which case there may not be one.

If you are talking that the relays are in your breaker panel, then that is a different story completely and we would need more information on how things are wired for the relays.

[moskovskiy82]

Well we have a 3wire system. So N is neutral and PE is protective earth and is a separate ground connection.
I was discussing the use of PE as a possibility. Occurance of a strong potential here is almost impossible but i guess due to induction there can be some.

[dbemowsk]

@moskovskiy82 Is the relay that you are replacing in the wall switch box or the breaker panel? Do you have any information on the Legrand relay that you are replacing?

[moskovskiy82]

@dbemowsk said:

@moskovskiy82 Is the relay that you are replacing in the wall switch box or the breaker panel? Do you have any information on the Legrand relay that you are replacing?

Not exactly...
Here we are awaiting a hex value

void receive(const MyMessage &message) {
if (message.type==V_RGB)
 {
hexstring = message.getString();
....

And than process those to rgb values. But if via MQTT we will receive RGB values like 243,145,156 and not hex - how to change the code accordingly?

[dbemowsk]

How did this go from a relay/power issue to changing RGB color values?