A technician measures 5.5 amps using a clamp-on ammeter on a thermostat wire. What should he set the heat anticipator to?

The correct choice is based on the understanding of how heat anticipators work in a heating system. A heat anticipator is typically set to a value that is significantly lower than the actual amperage reading from the system due to the way it is designed to function.

In this scenario, when the technician measures 5.5 amps, this measurement likely refers to the total current flowing through the system. However, heat anticipators are calibrated to prevent short-cycling of the heating system. Therefore, the anticipated load is usually adjusted to a fraction of the actual current.

Setting the heat anticipator to 0.55 amps (which is one-tenth of the measured 5.5 amps) is appropriate as it allows the heating system to function correctly without over-cycling, which can lead to inefficiency or system damage. The conversion from amps to tenths ensures that the anticipator prepares the system to turn off before the actual temperature is achieved, promoting energy efficiency and effective heating control.

Thus, the setting of 0.55 is reflective of the optimal adjustment needed for the system's performance.