National Electrical Code Articles and Information

Code Quiz: Article 427

Based on the 2017 NEC

Questions and answers written by Mark Lamendola, who has worked as a master electrician, electrical inspector, and design engineer. Mark is an IEEE Senior Member, and the Code article author for Codebookcity.com. Since 1996, he has been writing National Electrical Code articles for electrical trade magazines and has an extensive portfolio of hundreds of NEC articles.

Article 427 provides the requirements for fixed electric heating equipment for pipelines and vessels.

1. When doing your load calcualations, how must you characterize these heaters?
   

2. If the external surfaces of resistance heating equipment exceed 140 DegrF, what must you do?
   
3. If resistance heating equipment is not in direct contact with the vessel, what is the danger and how do you protect against it?
   
4. For impedance heating equipment, how do you isolate the distribution system from the heating system?
   
5. If a temperature controller with an OFF position opens just the "hot" wire, it will prevent the heating equipment from heating. Is there any problem with using such a controller?

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