What will the voltmeter read if the skin of the unit is not hot?

When determining the voltmeter reading in the context of the unit's skin not being hot, the concept of electrical potential becomes essential. If the skin of the unit is at a stable temperature and not exhibiting signs of overheating, this typically suggests that there is no excessive electrical current or potential that would manifest as a voltage reading.

In this scenario, a voltmeter measures the voltage difference across two points. If the skin is not hot, it indicates that there is no significant electrical fault or leakage current that could produce a measurable voltage. Therefore, it is reasonable to conclude that the voltmeter would read 0 volts. This outcome aligns with the idea that, under normal operating conditions where no faults are present, the potential difference will remain neutral or zero.

The other choices imply there is voltage present, which would suggest some form of electrical activity or issue that could cause heating, contrary to the established condition that the skin is not hot. This reinforces the understanding that a reading of zero volts is indicative of safety and proper functionality in this context.