Which measurement is typically recorded on the service invoice during preventive maintenance?

• A. Temperature readings
• B. Pressure readings
• C. Flow rates
• D. Volts and amps readings

Answer: (D)

When documenting preventive maintenance, the most important information to record on the service invoice is electrical operating conditions. Volts and amps readings show the actual electrical supply and the load on motors and circuits, which helps confirm everything is within design specs and safe to operate. Measuring voltage ensures the unit is receiving proper power, while current (amps) reveals whether motors or equipment are drawing the expected amount of current; deviations can indicate problems like shorted windings, failing components, or overloads. These electrical measurements provide a clear, objective record that supports payment, warranty, and future service decisions.

Temperature readings, pressure readings, and flow rates are valuable during the maintenance visit to assess performance and identify issues, but they are more commonly documented in service reports or field notes rather than on the invoice itself, which centers on the verifiable electrical health and readiness of the system.