These resistive loads are built to operate at 100% duty cycle in a 50 °C ambient without a cooling fan at the rated watts below at the usual equalization voltage commonly found in lead acid battery-based systems. At normal charging voltage, the amperage listed will be 5-10% less than listed and the watt rating will be 10-15% lower than listed…so, oversize the load unit a little ( 125% of the hydro potential ) when using the load unit for hydro, wind, or solar diversion. Mounting must be on a suitable fireproof vertical support as listed for height and width, with other fireproofing materials as needed. They must also be kept free and clear of combustible materials and falling debris. This is your responsibility! These units can be a significant source of heat and could be dangerous in the wrong hands. We assume absolutely no responsibility; use at your own risk. This is an industrial-grade product and is not UL-listed. The smaller units can be built and shipped in a day or two. Allow extra time for the larger ones.