Reviewing several of the 20 amp 12 wire VS 15 amp 14 wire comments I did a voltage drop check in my own house on the kitchen circuits and was amazed at the drop on them! They are wired in 12 ga wire. I became aware of the basic rules of wiring, longer runs equal voltage drop and it isn't 20 amps vs 15 amps its length vs load expected at the far end. Ya might need to run 12 to over come voltage drop on a 15 amp circuit or 10 on a 20 amp circuit. Since then I've re-thought my thinking on wiring circuits and upsize sometimes just a home run to cut voltage drop. May not be the cheapest route but too many "electricians" don't get past the wire size vs breaker size point of learning

3 way switch and an "ice cube relay". there are times I have run into problems with remods and a existing light circuit with a single pole switch needs to become a 3-way circuit and the existing single pole isn't excessable to change the wiring. I've got around this by using a ice cube relay in an approprate (excessable) box with the "old" switched run powering the coil. wire the C/NC/NO as a 3-way switch with the NC/NO as the travelers. Our local inspector couldn't find any reason to reject this creative idea. Only problem I have seen is it confuses some people on how it works. Also solves problem when the old circuit doen't have a ground and the new lighting needs one. In this case think of the old circuit turning on and off the relay (now acting like a 3-way switch) electrically as you would a normal switch by hand.

how far away from a spinkler head do you have to be to install a luminaire fixture