I am an in an apt. I micro grow and guerrilla ONLY.
It's not so much power spikes. Your odor control better be spot on and so stealth that if maintenece walks in for an emergency or something, it can't be seen. 600W is risky in my opinion due to the size of grow a 600w would be.
If it's your own home, then those aren't factors. In my apt. complex I've had them in 5 times for plumbing and electrical reasons. I was here 4 outa the 5, READ your lease agreement and see what the rules are for entry to your apt.
Change your locks. that way you'll know if landlord is goin in behind your back as well.
I would go 250w max in apt. and just supplement my herb not go big like a 600w+ just due to the possible security breaches that could easily happen. (i would think about 400w but then fan sizes increase and so does overall white noise from the grow. things to consider as well is noise)
I run around 180W grow in the closet. The one place they have no reason to go in.
but to answer your question..a 600W on 12/12 wouldn't even raise an eyebrow to the power company...thats too tiny for them to even care. Thats not even a stereo left on all the time..mine pulls 800w. Just be energy conscious
Peeps get mainly busted for stealing power and company goes out to investigate the 4000kw+ power loss in area.
Good luck and stay safe.