Hot-Shot 400 has a dual level output - with 400 amps of thawing power, it can thaw frozen lines up to 175 ft. long in 1-1/2" diameter lines; can switch down to 320 amps and pull just 14 amps ...
A good alternative to pricey pipe-thawing machines is a heating cable. These cables resemble a 3-prong extension cord and wrap around PVC or metal water pipes to help keep them from freezing.