Electrical Design

Part 9 – Sizing Motor Overload Protection and OCPDs

How to Size Overload Protection for 3-Phase Motors? NEC Article 430, Part III provides guidelines for sizing overload protection devices such as, overload relays, fuses and circuit breakers for motor…
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Part 8 – Sizing Motor Feeder Protection and OCPD’s Devices

How to Determine the Size of Feeder Protection Supplying Several Motors? In the previous section, we discussed sizing feeder conductors for multiple motors. This section will explain the step-by-step process…
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Part 7 – Sizing Motor Branch Circuit Protection and OCPDs

How to Select OCPDs and Right Size Breaker / Fuse for Motor Overcurrent Protection? Sizing Branch Circuit Protection for Motors The sizing of overcurrent protection devices (OCPDs) for motor branch-circuit…
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Part 6 – Sizing Motor Feeder Conductors and Cables

How to Determine the Correct Wire Size for Feeder Supplying Multiple Motors? In previous sections on motor circuit calculations, we determined conductor sizing, overcurrent protection, and overload protection with solved…
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Part 5 – Sizing Motor Branch Circuit Conductors and Cables

How to Determine the Correct Wire Size for Motor Branch Circuit? Sizing Motor Branch Circuit Conductors Sizing the conductors for motor branch circuit is selected at 125% of the motor…
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Part 4 – Calculating Locked Rotor Current (LRC) for Motors

How to Determine the Value of Locked-Rotor Current (LRC) for Induction Motors? What is Locked-Rotor Current (LRC)? Locked-rotor current (LRC) is the maximum starting current drawn by an electric motor…
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Part 3 – Understanding NEMA Motor Nameplate Data and Marking

How to Read NEMA Motor Nameplates Data Printed on It for Motor Circuits? What is NEMA? NEMA (National Electrical Manufacturers Association) is a U.S.-based trade association that develops and publishes…
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What is the Difference Between 15-Amp and 20-Amp Outlet?

Difference Between 15-Amp and 20-Amp Outlets and Receptacles Electrical wiring installations, equipment, devices, and other electrical systems for residential and commercial applications in the United States differ significantly in complexity…
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Why is the Long Prong Neutral Instead of the Narrow Prong?

Why is the Wide Prong and Slot Designated as Neutral Instead of the Narrow Prong and Slot in a Plug and Outlet? Engineers typically avoid making arbitrary choices when designing…
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Why is the Neutral Prong or Slot Wider on a Plug or Outlet?

Why is the Neutral Prong and Slot Longer than the Hot Prong and Slot on a Plug and Outlet or Receptacle? Although the electrical power supply and distribution system in…
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