Test the knowledge up front! There are just too many BS artists out there. Even most with a certification card are bogus - they knew how to read English enough to take a test. But I would definitely test on basic knowledge and hazards, as well as communication skills. (And I don't mean English - I have had guys who speak Chinese and Spanish as a first language be able to understand and comprehend what I tell them better than guys who speak 'Surfer dude' and 'Jethro'...) Up front - find out if they know what integrity means....
And unfortunately they also must be either "Certified" to work legally for you as a C-10 by our wonderfully unenforced state labor laws. Or be in either an approved apprenticeship program, or "Electrician Trainee" program. (Around our way there are two choices ABC or the Union - Legally not allowed to cover the same geographical area for training but over-lap for dispatch....) If you ever plan to leave this guy on the job by himself he would need to be certified, and if you do any commercial work - he would need to be a "General Journeyman". Otherwise he could be just a measly plain ol' "Residential Journeyman" and be limited in the work he could do legally even if he knew how to do it or not.... (IMO you are an "electrician" or you are not...) Long story short - casual apprenticeship is dead as you may have once known it. You have no penalty in hiring anyone you want at this time, but it would be a disservice to the guy you hire to carry him employed for you and have none of the experienced gained be counted in any way down the road.
As far as going rate - that really depends on the person and experience... You can get a guy who knows a lot but hardly shows up. And likewise a guy who doesn't know much but shows up and leaves on time and cranks out work. As far as pay rate goes, outside of SF proper, union scale is pretty equal, and starts to divide more and more as you get further out. In SF proper it would be close to Alameda Union scale for non-union work. Both only really differ in the benefits packages, and a trip across a bridge.
(Local 6 and/or prevailing wage are far beyond real local wages - not sure if they need a new calculator or I do.) Also beware of prevailing wage junkies of either flavor. They are like the wind, a wind that doesn't blow, but pulls in a strange way..... They screw crap up - and they're gone
and they know it - off to the next highest paying gig for a few months at a whack.
Either way, if you get a 'good guy' - KEEP HIM HAPPY! It might be a long time before you get another good one. Whats left of the labor market is currently filled with CRAP! The dot-com boom drove off the wider population of blue collar labor from our area, and all the good ones have jobs already. I'm not going to say I wish you luck - just be careful in who you actually hire - if you can get someone to answer an ad.