Electrical Code 3 Practice Test

Transformers and related equipment have their own dedicated article that lays out all the installation rules. This article covers how to place and connect transformers, what kind of enclosure and ventilation are required, how to handle oil-filled versus dry-type transformers, the necessary clearances from combustibles, and the required disconnecting means and overcurrent protection. It also addresses arrangements for transformer banks and any associated switchgear.

Other topics are governed by different articles: panelboards and switchboards have rules that apply to those devices and not to transformers; grounding and bonding are covered in a separate article; emergency systems have their own article. So the article focused on transformers is the one that specifies how transformer installations and their related equipment must be installed and protected.