I agree with wubears1 completely. 5500W is plenty for most applications. Takes me more like 60 to bring 13 gal of 65F water to boiling, but then I have plenty of water for brewing. I use one 5500W in my HLT with HERMS, and 1 in my BK for boiling. With a 50A GFI protected circuit (spa disconnect) I am able to run both elements, 2 march pumps, a BCS and a wireless router without tripping the breaker. In my experience, it's super convenient to be able to both run the HERMS during fly sparge and simultaneously bring wort to boil. This would be impossible to do if you were running two elements in one vessel.