(a) A Class C condition does not present an immediate hazard, but if not corrected, may become hazardous. The operator may leave the gas on.
(b) Class C conditions include, but are not limited to:
(1) any gas pipe or appliance which was leaking and has been temporarily repaired;
(2) situations where the clearance between combustibles and appliances or vent connectors are less than required but no immediate fire hazard exists;
(3) any gas piping or appliance connection identified as improper or inappropriate;
(4) vent connectors that have a rusty condition, no draft diverter where required, reduced size or are incorrectly installed but drawing satisfactorily;
(5) improperly installed appliances such as those identified in the National Fuel Gas Code - NFPA 54 (as described in section 10.3 of this Title); and
(6) any properly vented appliance developing excessive carbon monoxide.
(c) For vented room heaters, excessive carbon monoxide shall be defined as 0.02 percent CO in an air-free sample of the flue gases when tested in an area having a normal oxygen supply.
(d) For all other vented appliances, excessive carbon monoxide shall be defined as 0.04 percent CO in an air-free sample of the flue gases when tested in an area having a normal oxygen supply.