As an electrical contractor in Arizona, I started installing energy management systems for commercial buildings and dwelling units in the early 1980s. This was a long time before Article 750 was inserted into the 2014 National Electrical Code.

At the time, I specialized in electrical installations in industrial facilities, some commercial wiring for buildings and large dwellings that ranged anywhere from 5,000 to 40,000 square feet. These large homes often had electrical systems the size of small commercial buildings, with complex fire alarm, security and energy management systems.

Know what it does and how to use it

The energy management system provided control over large loads, such as air conditioning, kitchen loads, water heaters and others. For most of these early energy management systems, the owners needed minimal training to understand how to program and effectively use them. Many of the systems I installed had override capability for the owner, especially during really hot summer days. 

Most of these owners were fairly sophisticated with the energy management systems once they had instructions on how to use them. Newer energy management systems now can be programmed from a computer, tablet or cellphone, as well as the unit itself, and users are even more capable now.

Problems often occur when an original homeowner familiar with the system sells the home to someone who does not know how to use it. Energy management systems on new or existing homes can be frustrating for a new occupant. Such was the case for an owner of a large home in Mesa, Ariz., who was having problems with one or, at times, all three of the air conditioning systems shutting down every afternoon during the high summer temperatures.

When I first looked at the electrical system, I determined that the thermostats for the units were shutting down, but did not see an energy management system anywhere close to the panelboards in the house. Doing some research, I learned she has had this same problem for the last 3–4 years at about the same time every summer. She purchased the home about five years ago, and has had numerous air conditioning troubleshooters trying to fix this problem.

My grandson Steven, an awesome air conditioning technician, had previous experience with energy management systems on large homes. He located the problem within an hour or so and reset the system to bypass the three air conditioning systems, which solved the problem. No other technician had been able to do so.

NEC requirements

Section 750.1 in the 2023 NEC states that this article applies to the installation and operation of energy management systems. Most energy management systems have two basic requirements: (1) monitoring the system and (2) controlling the system. These requirements ensure that an energy management system does not overload a branch circuit, feeder or service or does not override a load-shedding system that would overload a system. 

Energy management can be listed as a complete system, a kit for field installation mounted in switches or panelboards or could consist of listed individual components assembled as a system. An electrical contractor can use the last option, especially when working in conjunction with a knowledgeable supply chain or manufacturer. With the price of power these days, an energy management system will almost sell itself, especially in hotter parts of the country. The lower cost of a system could far outweigh the higher installation costs of photovoltaic systems and provide energy savings.

When an energy management system is installed, take care to provide a directory as required in 750.50 that states as follows: A directory identifying the controlled device(s) and circuit(s) must be posted on the enclosure of the controller, disconnect or branch-circuit overcurrent device. 

Markings

The equipment that supplies the branch circuit, feeder or service loads must be field-marked with the maximum current setting, the date of calculation and setting, the identification of loads and sources associated with any current-limiting feature and with the following or equivalent wording: “The setting for the EMS current limiting feature shall not be bypassed.” 

The markings must meet the requirements in 110.21(B) and be located to be clearly visible to qualified persons before examination, adjustment, servicing or maintenance of the equipment. If these markings are installed appropriately, no one should have the problems like this homeowner experienced with frustration and possible safety issues.

stock.adobe.com / Konstantin L