So yeah, I know I could google the question, but I thought I’d put this here so you smart people can help out with future searches (and me in the process)
Can you help me understand, in simple terms, why do some sensors and switches require a neutral wire, but some don’t? What’s mechanically happening that changes this requirement? What makes the non-neutral-required ones cost more?
And just to appease the masses, (even though it’s been asked a thousand times), can I just get around this requirement by fudging the neutral for a ground? Why or why not?
So, basically, a neutral-less switch will allow a very small amount of leakage current out the load side purposefully in order to supply the internal smart circuitry with power, but not enough current to turn the light itself on. Whereas a switch with a neutral allows the smart circuitry to complete the circuit itself, without leaking current through the load side of the switch. The reason neutral-less are more expensive is due to the added bypass stuff to remove flickering and it is also sold as a ‘premium’ feature for ‘older homes built before 198x with neutral-less switch boxes’. Be mindful that even if the switch boxes dont have a neutral, the light fixture itself will. Switch boxes didnt need neutrals back in the day because there was no need to complete a circuit at the switch, only the load.
To answer why you cant connect a ground to a neutral line and have it work is because the ground is a safety mechanism used to short the electrons to the earth in a fault. Sending current over the ground wire is one hell of a good way to get shocked and be buying new electronics. It would essentially be the same as touching the hot wire to ground.
To complete the circuit and have electrons flowing back and forth as the NEC intended, you need to complete the circuit with a neutral, if you have a switch with a neutral wire that is built to use the neutral.