Final answer:
In a 480 volt three-phase system, the expected phase-to-ground voltage is typically around 277 volts, derived from dividing the line-to-line voltage by √3. Using the meter in the wrong mode, such as ammeter mode for voltage measurement, could result in damage to the meter or the system and pose safety hazards.
Step-by-step explanation:
In a 480 volt three-phase system, if you were to take a voltage measurement from one leg (phase) to ground, generally you would expect to read a phase-to-ground voltage that is lower than the phase-to-phase voltage. In a perfectly balanced system, this reading should be around 277 volts in North America or similar systems where the voltage relationships are based on a √3 (square root of 3) relationship between line-to-line and line-to-neutral voltages. This can be calculated using the formula √3 (1.732) = 480 V / 1.732 = 277 V. This is because in a three-phase system, the phase-to-neutral voltage is the line-to-line voltage divided by √3. However, it's important to note that this is an ideal scenario and actual readings can vary due to system unbalances or other factors.
When measuring voltage, it's crucial to use the meter in the correct mode. If you mistakenly set the meter to read amperage (ammeter mode) instead of voltage, you could potentially short circuit the meter or damage it if the meter is not capable of handling the current or if proper fuses aren't in place, which could also cause harm to the operator or damage the system.