EC&M Tech Talk Video — Transformer Requirements in the NEC and Beyond

In Episode 29 of “EC&M Tech Talk,” Randy Barnett, a journeyman electrician, inspector, author, trainer, and electrical safety expert, covers the topic of transformers found in Art. 450 of the National Electrical Code. However, not all of the required information for the proper installation of transformers is found in the NEC. In this Tech Talk, Randy takes viewers through how to use a formula from the study of basic electricity to find the values needed to determine the overcurrent protection requirements for transformers.

In addition to sizing overcurrent protection, Randy discusses the scope of Art. 450 to find out just what transformers are covered by the Article. The video demonstration uses a nameplate from a typical 75kVA dry-type transformer found in distribution systems to address various requirements of the NEC. Each of the required markings on the nameplate is discussed. These are listed in Sec. 450.11.

Randy also provides an overview of Parts II and III from the Article. This includes liquid-cooled transformers and transformer vaults. Like all electrical installations, compliance with NEC requirements is designed to meet the purpose of the NEC — the practical safeguarding of people and property from electrical hazards.