Final answer:
The size of an individual heater wire is dependent on the current it must carry, related to the heater's power requirement in watts at the given operating voltage. Horsepower is not used for electric heaters. The wire must carry the required current without overheating to avoid safety hazards.
Step-by-step explanation:
The individual heater wire size is dependent on the current it must carry, which relates to the power requirement of the heater in watts (or kilowatts). For a given power output, a higher voltage means a lower current is needed, and inversely, a lower voltage would result in a higher current for the same power. Horsepower is not generally used for electric heaters; it's a unit more commonly associated with engines and motors. The size of the wire in a heating element must be sufficient to carry the required current without overheating, which could lead to melting or fire hazards.
For example, a small electric heater with a heating element may consume around 1.0 kilowatt of power. If we know this heater operates at a common household voltage of 110 V, we can calculate the current using the formula I = P/V (where I is current, P is power, and V is voltage).
In this case, I = 1000 W / 110 V = approximately 9.09 A. The wire size must be chosen to safely handle this current. The current rating of electrical appliances, including the fuses and circuit breakers, also indicates the wire size needed. In the case of a nichrome wire used in radiative heaters, the characteristics of the wire, including its resistance and cross-sectional area, determine the length and size of the wire based on the power output and operating voltage.