This is a rough figure, but at 15 amps you will get approximately 6,000 BTU at 115 VAC. To do a good job, I think something like 30 amps at 240 will give you about 24,000 BTU. A gas flame runs away for putting out the BTU's, many 150,000 or better. I get 5 gallons to boil in about 20 minutes using propane gas, but there are quicker burners. I'm guessing your looking at a good 45 to 60 minutes getting 5 gallons to boil with electric, that with a lid on to retain the heat.