It may interest a few out there that I installed a 2-pole 60 amp 120/240 Volt 3 wire "whole house" Pass & Seymore unit on my first home around 1970 as a result of my wife getting a shock on a faulted electrical frying pan. When I moved to my new home in 1981, I relocated this same Pass & Seymore device and subfed this device to feed an all receptacle subpanel in my home (with the exception of refrigerator, freezer, and outdoor receptacles which have individual GFI's). Amazingly, this device is still working fine today and is still in service! It is amazing that the 5 milliampere trip unit only occasionally causes nuisance tripping considering it is on all of the receptacles and receptacle wiring on my 3200 square foot home. I used all Hubble commercial grade receptacles and I believe this makes a big difference on leakage current. I will say this device may have actually saved the lives of two of my three sons years ago when they both managed to stick metallic objects into receptacles and were betwen hot and ground. It has also tripped on other occasions when it should have. I have tested the unit and it still functions as it should after 38 years--what quality!