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National Electrical Code Articles and Information

Based on the 2011 NEC

by Mark Lamendola

National Electrical Code Top Ten Tips: Article 626, Electrified Truck Parking Spaces

When the NEC speaks of an electrified truck parking space, it's referring to the space. Not the truck. It's not talking about electrified trucks, it's talking about parking spaces that are electrified and that are for trucks.

So why would you want to electrify a parking space for a truck? Think of all the refrigerated trucks you see barreling down the interstate. These trucks are driven by people, and people have needs. They need to stop to sleep, refuel, eat, get some quick exercise, and to any of a number of other things that people need to do.

It's not just trucks with refrigerators that need electrical power. Many have heaters, because they carry livestock in severe weather, or carry flowers or other sensitive plants in chilly outdoor weather. And, of course, there are many other reasons a truck might need to maintain electrical power even while stopped for the night (or, depending on the trucker, for the day).

While the truck is sitting there, it could be running at idle to provide the power for its electrical system. But this is wasteful and it's a security problem. The truckers "could" rush around and hope the food doesn't rot while they're using the bathroom, refueling, or taking a quick walk. And maybe they could choke down their food fast enough, too. However, you can't rush eight hours of sleep. It's going to take eight hours. Thus, the truck needs an external electrical source or it has to waste fuel to power its electrical system.

That's why we have Article 626. Here are your ten tips:

  1. Article 626 covers the electrical equipment and conductors external to the truck [626.1].
     
  2. Article 626 modifies other applicable NEC sections. Where there's a conflict, Article 626 applies [626.3]
     
  3. Article 626 does not apply to loading equipment or the truck facility in general [626.4]. It applies to the parking space electrical system, only.
     
  4. If supplying from a 208Y/120 source, the wiring system must be grounded (a four wire system) [626.10].
     
  5. In a residential panel, you can size it smaller than the sum of the branch circuit breakers. But you can't do that on the panels for truck parking spaces. You must size the panel no smaller than the sum of the branch circuit loads [626.11].
     
  6. You have to base demand factors on the climate zone [626.11(B)].
     
  7. You must consider the loads to be continuous [626.11(D)].
     
  8. The requirements for the separable power supply cable assembly are extensive [626.25]. The main thing to keep in mind is anything you use for this must be listed for the purpose.
     
  9. The system must have a means to prevent backfeed, in the event of power loss [626.26].
     
  10. If the space is intended to provide power for Transport Refrigerated Units (TRUs), it must include an individual branch circuit and receptacle for operation of the refrigeration/heating units, in addition to any other receptacles [626.30].

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How the NEC is arranged

  1. The first four Chapters of the NEC apply to all installations.
  2. Article 90 precedes Chapter One, and establishes the authority of the NEC.
  3. Article 80 follows the body of the NEC; it exists as Annex H. It provides the requirements for administration.
  4. Chapters 5, 6, and 7 are the "special" chapters, covering special: occupancies, equipment, and conditions (in that order).
  5. Chapter 8 provides the requirements for communications systems.
  6. Chapter 9 provides tables.
  7. The appendices provide mostly reference information.
  8. Appendix D contains examples that every NEC user should study.

Try your NEC moxy:

  • Do you know the difference between bonding and grounding? Hint: Look in the NEC, Article 100.
  • Does the NEC refer to grounding incorrectly in any of its articles? Yes! So be careful to apply the Article 100 definitions. Don't ground where you should bond.
  • When doing motor load calculations, which Article covers hermetic motors? Answer: While Article 440 covers the application of hermetic motors, it does so only by amending Article 430 because hermetic motors are a special case of motors. For motor load calculations, refer to Article 430.
  • Does the NEC provide a voltage drop requirement? Yes! It does so in a special case, which is Article 648 Sensitive Electronic Equipment. But for general applications, it does not provide a requirement; it merely provides a recommendation in a couple of FPNs.
  • Take our Code Quizzes.

Remember other applicable codes, rules, standards, and references:

  • OSHA's electrical worker safety rules.
  • IEEE standards.
  • NETA standards.
  • NFPA standards.
  • International Codes (if applicable to the installation).
  • State Codes (if the state has them).
  • Local ordinances and permit requirements.
  • Local fire codes.
  • Manufacturer requirements or guidelines.
  • Customer security requirements.
  • Industry standards.
  • Your company's own internal standards, practices, and procedures.
  • Engineering drawing notes.

 

 

 

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