Each oil immersion heater must have the following:
(a) An operating thermostat.
(b) Heating elements that have no electrical contact with the oil.
(c) A high temperature limiting device that:
(1) Opens all conductors to the heater;
(2) Is manually reset; and
(3) Actuates at a temperature below the flashpoint of the oil.
(d) Either--
(1) A low-fluid-level device that opens all conductors to the heater if the operating level drops below the manufacturer's recommended minimum safe level; or
(2) A flow device that opens all conductors to the heater if there is inadequate flow. [CGD 74-125A, 47 FR 15236, Apr. 8, 1982, as amended by CGD 94-108, 61 FR 28283, June 4, 1996]
Subpart 111.87_Electric Air Heating Equipment