I was on a commercial in Hattiesburg, MS in July. We were shooting inside, but I setup a couple M18s outside lighting through a window. It was sunny when we setup. I didn't notice that the pitch of the roof would direct a torrent of water on the lights if it rained. It did. It didn't just rain, it was a cloudburst raining as hard as it could.
Fortunately, we had prepared for rain. The heads had rain hats on. The ballast were protected under a porch eave with rubber matting over them but still allowed ventilation which is so important with ballast.
We were able to keep shooting even in the rain.
I was worried about the M18s but they stayed reasonably dry. It helped that the heads are IP23.
I was lucky that we had great rain hats. These were Rob's Rain Hats sent with the heads from the great guys at Available Lighting in New Orleans.
We often just use rain screen. That would have been a disaster in this unusual, unique situation!
Update: The commercial from this post was nationally released this week. It is emotionally powerful dealing with the issue of Chronic Traumatic Encephalopathy (CTE) from playing sports especially football:
The key light on Brett and some of the background are the two M18s through a layer of muslin.
The commercial was produced by Yellowhaus based in Cincinnati, OH.
Update June 2022: This commercial has won several awards including a national gold Addy.