Final answer:
Section 422.12 of the National Electrical Code specifies the requirements for what other loads may be connected to the circuit of a central electric furnace heating system, with a focus on preventing thermal hazards through safety systems like circuit breakers and the three-wire system.
Step-by-step explanation:
When installing a circuit for a central electric furnace heating system, the National Electrical Code (NEC) has specific requirements regarding what other loads are permitted to be connected to the circuit. According to the NEC, section 422.12 specifies these requirements. Electrical safety systems and devices such as circuit breakers and fuses are put in place to interrupt excessive currents, thereby preventing thermal hazards. The usage of a three-wire system is also mandated for modern installations to protect against both thermal and shock hazards by grounding the neutral wire and appliance case. Additionally, safety regulations limit continuous use to 80% of the breaker current capacity to further prevent thermal overloads