What Equipment?

This sign is on a big, metal, yellow-orange box that was humming in the heat.  Was this box the ‘equipment’ and it had automatically started?  If not, where was it and what did it do and, most importantly… WHAT WAS SO DANGEROUS?? With no answers in sight, at least I got a selfie.


There wasn’t much to photograph during my break but sometimes even a cinderblock wall looks good when light glances from the side. The composition below makes use of side lighting. The nearly uniform gray tone contrasts with the details of the equipment panel and associated piping.