National Electrical Code Articles and Information

Code Quiz: Article 425

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 425 provides the requirements for fixed resistance and electrode industrial process heating equipment.

1. What is the VA or wattage rating limit for a branch circuit supplying fixed resistance and electrode industrial process heating equipment?
   

2. Does the three feet working space rule apply to fixed resistance and electrode industrial process heating equipment or can you go less than that?
   
3. Can you place this equipment within 6 feet of combustible material?
   
4. Can you use a unit switch as the disconnecting means for this type of equipment?
   
5. If a boiler is designed such that fault currents don't pass through it, and the pressure vessel is electrically isolated from the electrodes, do you have to ground any exposed non current-carrying parts?

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