Energy use reduction and management are common in electrical systems of today. Automatic or even manual control of utilization equipment, managed energy storage, and renewable power production are a few additional ways to remove load from the grid and reduce energy use and handle demand. Electrical appliances and other products are often manufacturered with energy efficiency ratings. Building heating and cooling equipment is available in energy efficient models, and this equipment is often the specification of designers and owners. As the efforts to reduce energy increase through government mandates and incentives, a careful approach to integrating energy management systems and energy controls must be taken by those installing energy management systems. Emergency and essential electrical safety systems must not be impacted. Often the quest to reduce power consumption and qualify as “Green” results in challenges in meeting minimum requirements in the National Electrical Code and, in some cases, the Life Safety Code, or others. It is important to realize that any energy management system, load control, green building construction, LEED building certification, and so forth, cannot supersede minimum safety rules for the electrical installations. Essential life safety and emergency system requirements always take precedence. Safety for persons and property depends on it. However, are inspectors verifying it?
Energy management installation and use is significantly growing in the short term and will impact electrical systems in residential occupancies and more commonly will be applied in commercial and industrial facilities. When buildings and electrical systems are constructed initially, most inspection jurisdictions have a process that manages a plan review process, construction inspection processes, and final issuance of occupancy certificates. Energy management systems and wiring are typically installed and commissioned long after the final inspection and certificate of occupancy are complete, unless the installation is part of the original construction. Today this is often the case. Many existing buildings and systems provide tremendous opportunities for owners to reduce energy consumption. Conscientious owners and facility managers are requiring that their facilities be retrofitted with simple or complex energy management systems that allow building systems to be controlled in a fashion that reduces and manages energy use. The interesting question is, Are those retrofits inspected for compliance and to ensure that the energy management system does not override or defeat any emergency or essential system loads? Chances are this work is being performed without permits and not inspected. After all, permits and inspections of these systems may not be required. The administrative regulations in many inspection jurisdictions clarify which installations that require permits and inspections, and those that do not. In either case, the jurisdiction usually has a general requirement that whether an installation requires a permit and inspection or not, compliance with applicable codes is required. Final compliance with codes and standards always rests with the owner, even for existing building retrofits. Those performing energy audits and performing energy solutions services should verify with the authority having jurisdiction what permits and inspections are required, if any.
In all the efforts to reduce energy use in buildings, various continuous duty loads such as lighting, power, HVAC, and others must be carefully analyzed during energy audits to determine which loads can be controlled to reduce energy use and which loads can not. Usually large loads are targeted first, especially large lighting loads. One of the first loads to be adjusted in large commercial office buildings is the lighting load. The lighting loads can be automatically controlled centrally to reduce energy use as one method of energy management. Lighting loads can also be controlled locally by using occupancy sensors to switch the lighting on while occupied and off when vacant. Another popular technique used to reduce energy use is to change the type of lighting to more modern and energy efficient technology. As an example, many of the standard core-and-coil ballasted fluorescent style luminaires are being retrofitted with LED conversion kits. This retrofit requires removal of the ballast, sockets and wiring to allow for installation of the new LEDs, power supply, and associated wiring harness. The 2014 edition of the NEC includes a new definition of the term Retrofit Kit and indicates that it is a “complete subassembly of parts and devices for field conversion of utilization equipment.” The term retrofit kit appears in two NEC rules. Section 410.6 requires retrofit kits used for this purpose to be certified (listed) by a qualified electrical testing laboratory. The same requirement is also now applicable to electric signs and outline lighting systems as provided in 600.3. This requirement means that the retrofit kits installed must be listed and there must be compatibility between the kit and the luminaire or sign that is being retrofitted. Again, this is no longer an anything goes situation. Additional information about listed retrofit kits for luminaires is included in product category (IEUQ) in the Guide Information for Electrical Equipment (UL White Book) published by Underwriters Laboratories (UL). Product category (UYWU) includes information about listed retrofit kits for sign conversions. Those involved in providing these energy solutions for customers should understand the requirements for listing and that it is one aspect of attaining approval from the authority having jurisdiction. That is — if the project is permitted and inspected. Even if it is not, building owners should require this.
One of the most important steps of achieving effective energy reduction and management is having a quality and comprehensive energy audit. An energy audit is a point-in-time report to provide a look at how an electrical system is functioning during the time of the audit. The auditor should be experienced in the minimum requirements applicable to building electrical safety systems as well as any applicable life safety codes that could be affected. They must also fully understand which loads can be controlled by energy management systems, and which loads can not be controlled. Controlling or switching essential electrical safety systems loads that must remain operational could compromise safety for building occupants. This need to remain operational is one of the reasons why fully understanding both the electrical systems and the energy management business is important. Periodic audits are needed to ensure that an installation does not exceed its original design capacity. Energy management is not an anything goes situation, it requires expertise in electrical systems and applicable codes and standards.
The process of energy management has two basic yet essential functions: monitoring the system and controlling some portions of the system or equipment. Both of these functions must be implemented concurrently in order for the energy management system to monitor and possibly restrict control that would adversely impact the electrical system or personal safety. The most important system function here is to ensure that the energy management process does not override any essential systems. Limited consideration is found in electrical installation standards in actively managing these systems as a means to reduce energy cost or support peak power needs as it relates to a broader electrical infrastructure demand. Obviously for energy management systems to be effective, a tight building envelope must be established. This work is beyond the scope of the NEC, but is an essential part of effectively reducing energy costs in existing facilities, especially older facilities.
While much of the increased energy management focus and Smart Grid initiatives in this country are often voluntary, others are mandatory because they are driven by regulations in adopted energy codes. There are other energy codes being adopted and applied in various jurisdictions across the country. These energy codes include performance requirements that directly affect the electrical installation. In simple words, the performance requirements in adopted energy codes will drive the applicable prescriptive NEC requirements that apply to the installation or system. In some instances, there are prescriptive rules in the energy code(s) that are more restrictive than those in the NEC. As an example, Section 8.4 of ASHRAE 90.1-2013 includes mandatory voltage drop rules that are requirements, not just design considerations, as they appear only as non-enforceable informational notes in the NEC. Section 8.4.1.1 indicates that feeder conductors be sized for a maximum voltage drop of 2% at design load, and Section 8.4.1.2 indicates that branch circuit conductors be sized for a maximum voltage drop of 3% at design load. Another requirement of ASHRAE 90.1 is for automatically controlled receptacles. This rule requires automatic control of not less than 50% of 125-volt, 15- and 20-ampere receptacles in all private offices, conference rooms, rooms primarily for printing and/or copying functions, break rooms and individual workstations. This rule is a performance requirement more restrictive than the minimum NEC requirements and necessitates installing additional wiring and a means of automatic control. Those involved in electrical system design, engineering, and installation must be aware of the differing requirements. When two codes apply to the same aspect of an electrical system and they differ, conflict is usually the result. Many jurisdictions understand that conflicting requirements can arise between codes adopted and enforced by the same jurisdiction. In those cases, they handle this in a fashion that renders the more restrictive of two identical requirements as the one that must be complied with. There is a rapidly developing need for standards development organizations to coordinate the requirements of safety and performance codes so correlation exists, rather than conflict. This coordination requires communication between the standards development organizations (SDOs) during the standards development processes. It’s all about communication.
The 2014 edition of the National Electrical Code contains the prescriptive electrical requirements that are widely adopted as law in the North American electrical safety system. New Article 750 titled “Energy Management Systems” resulted from work of a specifically assigned NFPA Smart Grid Task Force responsible for identifying gaps and needs in the NEC relative to energy management. The new article includes a few important definitions, information about essential alternate power systems loads that cannot be controlled, and a section that permits load shedding and disconnection of power. The rules are necessary to prohibit them from being disabled by energy management control. The new article also prohibits energy management systems from causing any branch circuit, feeder, or service to be overloaded, a very important function. Another interesting requirement applies to energy management systems that remotely control building systems. The Code requires that a directory of the controlled device(s) and circuits(s) be posted on the enclosure for the controller, disconnect, or branch circuit overcurrent device.
This addition means the NEC is now equipped with basic requirements that address energy management and supports the safe and sound growth of this important aspect of most building electrical systems. The NEC is the set of rules that clearly address electrical loads that qualify for energy management and those that do not. There are abundant opportunities for qualified contractors that offer energy management solutions and smart grid services in addition to traditional electrical construction. Any energy management or energy efficiency project or service must be performed in a fashion that does not compromise any emergency or essential electrical system loads from being operational when needed. Examples of loads that should not be controlled by energy management are pressurization fans for exit stairwells, lighting systems in the path of egress, ventilation systems that run to remove or exchange air and achieve lower hazardous area classification. Other examples of loads that cannot be controlled by energy management are circuits supplying patient care areas in health care facilities. The point here is that while the adopted energy codes contain performance provisions to reduce and manage energy use, the adopted NEC contains the rules for energy management systems. The industry must be familiar with all applicable adopted codes in the jurisdictions where energy management work is performed.
So what affect does an energy management system have on electrical safety in buildings? And, what rules ensure that energy management systems do not impact minimum requirements for building systems that must remain operational? These challenges are most common among designers and engineering teams engaged in providing energy management services for existing buildings and achieving energy efficiency in new construction. There are new energy management system rules in the National Electrical Code that must be applied to electrical system designs to ensure code-compliance is maintained.
Wiring in many buildings includes a normal system and an emergency system, of some sort, depending on the occupancy and requirements in the Life Safety Code. Energy management systems are installed to improve energy efficiency by reducing load on the service. This dependency means that energy management requires electrical loads to be controlled depending on needs, time of day, and so forth. Often there are essential loads that must remain operational for building safety and safety of the occupants. For example, in a hospital, the essential electrical system also includes the critical branch, life safety branch, and an equipment branch. These loads are essential for safety of persons in the health care facility. Disconnection of power or overriding the controls of either the life safety or critical branch of an essential electrical system of a hospital by the energy management system is not permitted. Section 750.30(B)(4) applies to Article 700 emergency lighting systems in health care facilities except as amended in Article 517, and it applies to other occupancies requiring an emergency system. The process of energy management should not interfere with or defeat a required essential or emergency electrical system.
Automatic load management is also now included in a few NEC rules as an alternative to deal with service or system capacity requirement such as for electrical vehicle supply equipment (EVSE) installations. The key to properly applying these alternatives is to ensure that a feeder or service is not overloaded. Former 625.14 has been relocated to 625.41 and revised to indicate that where an automatic load management system is used, the maximum electric vehicle supply equipment load on a service or feeder must not exceed the maximum load permitted by the automatic load management system. This provision is an alternative that can be applied when the service or feeder capacity is not capable of supplying the continuous duty load of connected electric vehicle supply equipment. In new installations, the load on a service or feeder is typically calculated for sizing the service with the entire connected load and applicable demand factors. This alternative would typically recognize that the load could be managed so the capacity would not be exceeded and would usually be applied on existing services and feeders where the capacity is less than necessary to handle the EVSE load. It is important to note that the NEC does not indicate that the provisions in 625.41 apply to existing installations only. This is another example of the NEC evolving in a manner that supports the sound growth of the fast emerging electric vehicle market and required charging infrastructure needs.
Another change in the NEC relating to automatic load management is a new exception to 220.12. The new exception recognizes that where a jurisdiction adopts an energy code, lighting load calculation values need to be consistent between the NEC and any adopted energy code. Without this exception, a conflict is often created. The basic conditions of the exception are that an energy code is adopted by the jurisdiction, the power system is monitored and equipped with appropriate alarms, and the demand factors of 220.42 are not applied to the general lighting load. This exception is new ground for the NEC, but necessary as energy management incentives and mandates increase by adopted energy codes. Section 220.12 generally requires lighting load calculations for specified occupancies in accordance with Table 220.12. The exception relaxes these requirements for a building that is designed and constructed to comply with an adopted energy code under the following conditions:
- A power management system is installed that provides continuous information regarding the total general lighting load.
- The monitoring system is equipped with alarms to alert building owner or manager that the lighting load exceeds that allowed by the energy code and,
- The demand factors in 220.42 are not applied to the general lighting load.
Summary
Electrical systems controlled by energy management systems must meet all adopted regulations. The new Article 750 in the 2014 NEC contains important requirements relative to energy management systems and clarifies which systems and circuits cannot be controlled by energy management systems. Standards development organizations producing rules that address energy use and management and electrical safety must collaborate effectively to avoid conflicting requirements and reduce possibilities of compromising emergency and essential electrical system operation.
