02-658 C.M.R. ch. 110, § 12 - Electrical Wiring and Equipment

1. The following standards must be met for the electrical wiring and equipment used in connection with solid fuel burning equipment:

A. The electrical wiring and equipment used shall be installed in accordance with NFPA #70 (National Electrical Code);

B. Safety control circuits shall be two-wire, one side grounded, having a nominal voltage not exceeding 150 Volts. A safety control or protective device shall be connected so as to interrupt the ungrounded conductor; and

C. The control circuit shall be connected to a power supply branch circuit fused at not more than the value appropriate for the rating of any control or device included in the circuit.

2. The following additional standards must be met for solid fuel burning appliances that are automatically fed:

A. Electrical Equipment, Required Control Switches

(1) Thermal Electric Switches. A thermal cut-off switch shall be wired into the burner circuit to shut off the burner in the event of a fire at the unit. The switch shall be placed directly above the unit to be fired with the thermal element pointed downwards and shall be placed at the front of the unit. The switch shall be no lower than the highest point of the flue connector where it enters the chimney. The switch shall be wired to shut-off the burner, circulating fan, forced or induced draft fan and any remote fuel delivery device that is not an integral part of the burner. A thermal electric switch is required for each unit in a multi-appliance installation.

(2) On multi-appliance installations the emergency and thermal electrical switches shall be wired, in series through individual unit relays such that, if one thermal switch or the "EMERGENCY" switch is open, the combustion air fan and fuel delivery system will be shut off. This also applies if there are two or more appliance rooms in the same building connected to a common fuel supply system.

Note: An example of wiring for multi-appliance installations is illustrated in Figure SF-2.

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B. Disconnect Switch

A burner disconnect switch shall be placed within three (3) feet of the burner.

C. Emergency Switch(es)

(1) An identified switch to shut down the boiler, furnace or water heater in an emergency shall be placed outside of and adjacent to the entrance to the room where the appliance is located.

(2) If the entrance to the boiler room is only accessible from outdoors, the emergency switch may be placed inside not more than one (1) foot beyond the door opening.

Notes

02-658 C.M.R. ch. 110, § 12