The National Electrical Manufacturers Association is at present attempting to standardize thermostat markings in order to aid the installer in wiring and servicing. Thermostat terminals have been given standard identification letters that specify the function of the terminal. These identification letters are also matched, in most cases, with the color-coding of the wire. A partial list of equivalent terminal markings is given in Table 4-1.
Thermostat installation literature will generally contain at least one internal view and/or wiring diagram in which the various terminals are identified by a specific letter.
