We go by the NEC here regarding wire colors. My generous use of wire ties comes from my background in wiring machine controls. I used stranded wire on this job which doesn't stay put very well. I also do a lot of remodeling and could remove all these ties in a minute.
Dave
P.S. Some final comments before we let this thread die are:
I used a 2" nipple even though it's only 100-amp in case it got changed out later to a 200-amp service, which are getting more common here. I used duct seal in the nipple after taking this picture.
I plugged the four mounting holes with fender washers even though the holes aren't quite as large as a 1/2" knockout.
