Shared 480 Hot Leg

the catfish

Our electrical engineer on a site lighting job has spec'd out a three wire and a ground for three separate 480v circuits, sharing a hot for every circuit. I have seen this before but not often and am curious as to the reason. Seems as it could get a little confusing on the install and after 40+ different style lights, one crossed leg could cause a lot of headaches. Is this a common 480v practice? I am familiar with the theory but not the practicality.

mdshunk

It's a good way to balance the load and help with voltage drop. First fixture, AB. Second fixture, BC. Third fixture, CA... and it repeats. Best thing to do is take a brown, orange, and yellow magic marker and color code your site lighting plan. Mark each fixture on the plan with the colors of the two legs that get connected to that fixture. Even if you do mess up one or two, you'll just have one leg with an amp or so higher draw. No big deal.