"return", "common", "neutral"

WITH CIRCUIT CONDUCTORS AND SAFETY GROUNDING PROVISION:

This subclass is indented under the class definition. Electrical connector combined with a electricity transmitting member for supply of electrical current, a second electricity transmitting member for return of that electrical current (i.e., a return ground) and with additional, distinct, particular provision to electrically connect a portion thereof to the earth, in addition to or other than the provision of an electromagnetic or electrostatic shielding ground.

(1) Note. This subclass is to provide for any electrical connector including a grounding provision, except (a) one providing for a return path to earth of electricity that has been transmitted to an appliance that has utilized the electricity passing therethrough or (b) one purely for shielding the effect of electromagnetic or electrostatic radiation. Such provision may be called a "return", "common", "neutral", etc. ground. In the event of doubt of whether or not the provision is an "earth" ground or a "return" ground, the device is to be found in this and the indented subclasses.

(2) Note. In the transmission of low voltage electricity, it is not unusual to utilize the framework of structure to serve as a return for electricity. Such a return path is not considered to be a "common" or "return" ground. Terminology that may be indicative of structure including a ground that is not a safety ground includes: "tube socket", "transistor", "chassis", "electronic", "radio circuitry", "electrical shield", etc.

https://www.uspto.gov/web/patents/classification/uspc439/def...