1200 Pure Sine Inverter with Transfer Switch - ETL Certified to conform to UL 458 standards. This inverter is ideal for built-in RV refrigerators or other appliances. Easy to install. The inverter will switch between shore power and battery power without any extra wires. Many RV'ers and mobile businesses like to use residential size refrigerators and this is the perfect solution. Smaller microwaves and coffee pots are also common uses for this inverter. One of the standards of UL 458 is that all AC inverters pass a High Voltage Dielectric Withstand Test, commonly called the Hi-Pot Test. The voltage applied to the control is usually equal to 1,000 volts, plus two times the line voltage rating of the inverter. Therefore, the standard hi-pot voltage for 115 VAC inverter is 1,250 VAC. For 230 VAC or dual voltage inverters, the hi-pot voltage is 1,500 VAC. This Aims power inverter is hi-pot tested before it leaves the factory, with a UL Certified hi-pot tested, set to the voltages shown above.