Question: what is the difference between ac and dc testing?
Answer: The best voltage for a DC hipot is normally higher than the AC test voltage by a factor of 1.414. A product that would be tested at 1500V AC would be tested at 2121V DC. For double-insulated products, the required test voltages may be much higher, such as 2500 VAC or even 4000 VAC for a 120 VAC power tool.