Your electrician is a worry,the dimmer comes with sticker over the slave terminal warning not to connect to mains ! You do not require any additional wiring. Neutral connections are not required at the dimmer. You better check the dimmers are working before you pay the 'electrician'
Remember, if you have a bathroom fan you can't use a that dimmer.
Regards,
DS
Remember, if you have a bathroom fan you can't use a that dimmer.
Regards,
DS