Cognitive dissonance is when two or more thoughts or feelings you have are in conflict, or a thought/feeling and an action. Our brains like consistency, and our egos especially like self-consistency, so this conflict feels unpleasant. Its like if you pointed out something someone did wrong, and someone said "well you do that too". All of a sudden your brain is like "shit, i think doing that is wrong but i did it", and that feels uncomfortable. Often times the solution is to justify the conflict by pretending there isnt one, for example by saying "its okay when i do it because..."

There might be wires to the side of the stud, but theres no wires between the stud and the wall, the stud is right up against the wall. As long as you're drilling into the actual stud theres no possibility of hitting wires.

Dude...

Leading edge or trailing edge is the difference of which part of the wave form the dimmer cancels out to reduce the average current in the circuit, thats exactly what i was describing in my comment.

>they switch said AC current on/off at an adjustable time after the start of each half cycle, thus modulating the width of the pulses of current sent through the circuit

Leading edge vs trailing edge is just whether the circuit is turned back OFF during the half cycle, or turned back ON during the half cycle. You literally dont understand the technology enough to recognize a description of how it works. If all the ones youve installed have been leading edge or trailing edge, theyve all been solid state dimmers.

Also, he needs a 120V AC to 12V DC adaptor either way, so honestly he could use an AC dimmer OR a DC dimmer.

*varistor, which is short for varying resistor, a component for which its resistance changes with the applied voltage, meaning it doesnt have a set ohm rating. A potentiometer isnt a varistor, and a varistor wouldnt be a very good dimmer, considering its ability to affect current is dependent on the voltage being applied to it, meaning to use it to dim anything, youd need to be able to dynamically reduce the applied voltage, meaning youd need a dimmer for a varistor to work as a dimmer. Also, the dimmers im talking about are made for AC current, they switch said AC current on/off at an adjustable time after the start of each half cycle, thus modulating the width of the pulses of current sent through the circuit, like i said, a version of pulse width modulation. You ever seen a dimmer switch in a house? Most likely a solid state dimmer.

You're thinking of a rheostat, and those are very outdated for the purpose of dimming lights. Theyre big, inefficient, and get crazy hot. Nowadays most every dimmer youll find, especially in residential electrical, are gonna be solid state dimmers, which use variations on pulse width modulation.

If you plug it into an outlet with a dimmer switch, or get one of those dimmer adapters that goes between the plug and the outlet.