Electrical Fundamentals

Ohm's law for techs, series vs. parallel, reading a meter, capacitance, 240V single-phase and the 24V control circuit.

6 guides

• Electrical Safety: Lockout/Tagout and Working Hot
  Lockout/tagout the field-tech way — why you de-energize before you touch anything, how to lock and verify dead, the narrow cases where working hot is unavoidable and how to do it less dangerously, and the arc-flash and PPE basics that matter on residential and light-commercial HVAC.
• Ohm's Law and the Power Equation for Techs
  Ohm's law and the power formula explained for HVAC field work, with the practical mental shortcuts a tech uses to sanity-check amp draws, size a circuit, and spot a fault by the numbers.
• Reading a Multimeter for HVAC Work
  A field guide to the four meter functions an HVAC tech uses every day — AC volts, resistance, amperage, and capacitance — including how to set up the meter, where to place the leads, and how to read each measurement safely.
• Series and Parallel Circuits in HVAC Wiring
  How series and parallel wiring show up in real HVAC circuits — safety strings, heat strips, multiple loads — and how knowing which is which speeds up troubleshooting.
• Single-Phase 240V and the 24V Control Circuit
  How residential split-phase 240V power is structured, where 120V comes from, and how the 24V control circuit branches off it to run the thermostat and switching — the power picture every tech needs in their head.
• Voltage Drop and Finding Bad Connections
  Why voltage-drop testing under load finds bad connections that an ohmmeter misses, and how to walk a circuit to pinpoint the high-resistance joint that's making heat and killing components.

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