That's what they use to do before the 4prong boxes were available (tie the ground and neutral together) It kind of defeats the purpose of a seperate path to ground from the case of the device. I think the biggest issue is that your dryer breaker is probably a 40amp and your compressor only needs... say about a 15 or 20amp. Your compressor could smoke to the ground before the breaker would trip. (Just another thought...)Originally Posted by Francesco Rizzo