within motor housing 28 will be about the same as the surrounding atmospheric pressure under these conditions shaft grounding device 16 can be momentarily unscrewed from within hole 142 and inspected without an excessive exchange of gas between system 10 and the surround atmosphere 32 provided opening 142 is not too large preferably opening 142 should have a cross sectional area that is less than 4 in 2 the refrigerant pressure within system 10 can be adjusted to atmospheric pressure by adjusting the temperature of the refrigerant which can be done in various ways the water flow rate through evaporator 40 for instance could be adjusted while compressor system 10 is de energized it is also conceivable to heat or cool the refrigerant by adjusting the temperature and flow rate of the water flowing through condenser 40 fig5 illustrates the steps of adjusting the temperature of the refrigerant until the refrigerant in motor housing 28 is at a pressure substantially equal to that of the surrounding atmosphere 32 and removing shaft grounding device 16 from within motor housing 28 while the pressure of the refrigerant is substantially equal to that of the surrounding atmosphere thereby providing an opportunity to inspect shaft grounding device 16 without having to evacuate the refrigerant from within motor housing 28 this is possible because compressor system 10 has only one duplex rolling element bearing 22 that needs protection from induced common mode voltage the shaft 39 s other bearing 58 which is installed at a less accessible location deep within compressor system 10 is a journal bearing which is much more tolerant of induced common mode.