I use a steam humidifier like the one Vicks makes. I keep it on a wireless timer. One hour on one hour off. Holds humidity fairly well at 45-55 percent even with the occasional door opening.
I know this post is old but I had the same issue. Finally figured out that my two grow lamps were touching each other and somehow causing a short. I put electrical tape between the edges and was able to turn the power back on without any further issues. So simple but it took me hours to...