I know about 200VAC safety just on theory.. Actually I've worked with it but not so much.
So what's a random-phase unit and zero-crossing detector? Sorry for being a noob.
A triac, which switches the load, has the characteristic that once it is triggered into conduction, it continues to conduct until the load current falls to some near-zero value.
The way a triac is used in a dimmer is to switch it on at some variable point on the sine wave. When the current drops to zero (when the sine crosses zero), the triac turns off, then the triggering circuit repeats the same thing on each half-cycle. Where on the sine wave the triac is turned on determines the amount of power delivered to the load and hence the brightness of the lamp.
This process generates a lot of EMI due to the sharp step in current when the triac begins conduction. Usually lamp dimmers have filter circuitry to reduce the EMI generated.
Another way to reduce EMI is to turn the triac on immediately after the zero-crossing point on the sine wave. However, this means that the triac will conduct for the entire half-cycle. It also means that this type of circuit can only be used for on/off control.
PunkoHead:
Ok, found PR36MF12NSZF. Will I need more parts to do 220VAC dimmer?
Yes. See the sample circuit in the datasheet for starters. Also, the Arduino will need a way to detect zero crossing, then delay turning on the SSR until some later point in time to control brightness.
Good luck. GIYF. Keep one hand in a pocket so you don't electrocute yourself.