Zero-crossing detector?

[amgen]

you are right, with no transformer, any part of your circuit could be 100 to 200 volts to ground since you can never be sure if the wall plug/receptacle is reversed, (a shock hazard). But that won't matter if no parts of your circuit are exposed to touch.
I made a nice simple Xformer-less supply for push button pic/fan timer that picks up a 10amp relay. Has worked well over a long time.

don
amgen