The National Electrical Code (NEC) and HVACThe National Electrical Code and Heating, Ventilation, and Air Conditioning have some shared roles for both electricians and HVAC Installers and technicians. There are some specific categories in the NEC that are applied to HVAC and making calculations for circuits and wire sizing for HVAC appliances. Aside from the specific categories and chapters in the NEC that are directly applicable to HVAC and HVAC appliances it is important that every technician has a basic understanding of the NEC in all aspects especially the categories and chapters that are specifically applicable to HVAC and HVAC appliances.

The Importance of the NEC | The National Electrical Code (NEC) and HVAC

The National Electrical Code (NEC) and HVAC - Admittedly the NEC can cause sleep and/or great frustration at times. Do not operate heavy machinery and make sure you take a deep breath if you become frustrated with reading the National Electrical Code. Seriously, the NEC is a serious book and important to understand especially for those responsible for sizing wire, disconnect boxes, and other related electrical devices for HVAC.


In the commercial world of new construction, an engineer would determine the correct wire sizes and disconnect boxes necessary for all the equipment. Sometimes but not always in the commercial retrofit market, an engineer will also determine the correct size of all electrical devices necessary to replace or add HVAC equipment. Whether an engineer of the record made the determination for sizing circuits and electrical devices it is always a good thing for the technician to know the correct sizes as the engineer of record determined.

Sharpening Skills through Learning

From my personal experience before I became a Master Electrician whenever we needed a new circuit ran we called an electrician or an electrical contractor to do everything including the calculations for the circuit. Throughout the site, I tell everyone whenever they are in doubt call a professional so this article or series of articles in no way is intended to replace any professional and competent level of service. This article is simply intended to help technicians sharpen their skills and understand another related trade that parallels the HVAC trade. Something I wish I would have had when I was cutting my teeth.

The National Electrical Code (NEC) and HVAC: The Basics

NEC Chapter One

Chapter One of the NEC covers why the code exists and what it covers and what it does not cover. including requirements for installations. Definitions are also included including acronyms e.g. AHJ or Authority Having Jurisdiction.

Basically a lot of definitions which anyone with a technical background can familiarize themselves to improve their technical vocabulary.

Can you confidently define the following electrical words or terms as defined by the NEC?

  • Bonding Jumper
  • Feeder
  • Disconnecting Means
  • Grounded Conductor
  • Grounding Conductor
  • Overload
  • Qualified Person
  • Utilization Equipment

These definitions and others are included in Chapter One of the NEC and are considered to be comprehensive enough for one to gain a basic understanding of the electrical trade and to understand the electrical code.

Article 110 in Chapter One of the NEC covers requirements for electrical installations. Of note or pertaining to HVAC is limited in this chapter. There are similarities in the NEC that can be compared to basic common sense as far as installation of equipment is concerned for accessibility and guarding the equipment.

NEC and HVAC Basics: Chapter Two

NEC and HVAC Basics: Chapter Three

The National Electrical Code (NEC) and HVAC

The National Electrical Code (NEC) and HVAC: The Basics