I did a service call the other day where I was trouble shooting a ground fault on the spa circuit. While I was there I noticed that the electrcian before me had mounted the 50 amp. sub panel for the spa underneath a window. The bottom of the panel was approx. 12 inches from the finish grade of the flower bed. Which brought up another question in my mind of the potential of water in the panel via an irrigation line. But any way I was curious about the minimum mounting height requirement for a panel in this case.