Relay switched systems are pretty common in Europe, I'm pretty surprised they don't exist in NZ. Realys can be mounted in a box or in a DIN rail panel and are either 230V or 12V AC operated (230V being far more common). Most "modern" electricians use those systems where ever they have to control lights from more than 2 points. If you want a dimmer you have to switch out the relay, the switches stay the same.
Everything works with simple bell buttons. One push: on. Second push: off. Dimming: push: switch to previously set state. Hold: dim from low to full until button is released. There are both mechanic relays and electronic flip-flops. I don't like either of them because I think it makes the wiring a mess if you have to run every light feed back to the panel and the mechanic relays make quite some noise. And don't even ask me about adding anything electronic to 230V house wiring
