The 22nd edition of the Canadian Electrical Code, which has been extensively updated to improve safety and address changes in new technology, contains over 180 new requirements and revisions. Some of the most notable changes include:
- revisions made to the conductor ampacity tablesand ampacity calculation methods
- new requirements to facilitate maintenanceof roof top equipment
- updated requirements for receptacles indwelling units and child care facilities
- new requirements for electrical vehiclecharging equipment
- changes to the requirements for the installation of solar photovoltaic systems, and
- a completely new Section to address emerging technologies associated with renewable energy systems such as wind and micro-hydro
Fuel cell power plant at Sierra Nevada Brewery. Permission by Fuel Cell Energy.
These changes will enable Code users to keep pace with emerging technologies and will provide positive benefits to the entire industry. As noted, the 2012 CEC will introduce Code users to several important changes; however, the development of the new Section 64 which covers the installation requirements for renewable energy systems is truly significant. The focus of this article will be to provide an overview of the background and development of this innovative Section, as well as a snapshot of several of the new “General” requirements.
Section 64which is titled“Renewable energy systems”was added to the Code in order to keep pace with technological change and promote the benefits of renewable energy systems which include:
- reducing global warming
- conservation of natural resources
- protecting air, land and water
- improving health, and reducing health carecosts, and
- creating jobs
The increased promotion and installation of renewable energy systems resulted in a need to create a standard which would cover the requirements for the safe installation of electrical systems related to these renewable energies. The development of Section 64 was by no means an easy undertaking. CSA realized they needed an individual with exceptional leadership skills, as well as a solid understanding of codes and standards pertaining to renewable energy systems, and appointed Shawn Paulsen to take on the formidable task of developing this much needed new Section. Shawn is a past president of the Canadian Section of the International Association of Electrical Inspectors and a member of the International Board of Directors. Shawn established a diverse subcommittee with members representing regulators, various industry experts, utilities, and consumers. The project required extensive research of existing documents for relative installation requirements such as those found in the NEC and the IEC. The subcommittee’s efforts resulted in a comprehensive new section which includes 75 rules, 52 definitions and 65 Appendix B notes that identify the installation requirements for fuel cells, small and large wind systems, micro-hydro and hydro-kinetic systems, inverters, and batteries.
As with other sections in the CEC, Section 64 is carefully subdivided and provides a scope, special terminology, and the following subsections:
- Stationary fuel cell systems
- Small wind systems
- Large wind systems
- Micro-hydropower systems
- Hydrokinetic power systems
- Storage batteries
The scope indicates that Section 64 applies to the installation of renewable energy systems except where the voltage and current are limited in accordance with the Class 2 circuit requirements as outlined in Section 16, Rule 16-200(1)(a) and (b) or solar photovoltaic systems within the scope of Section 50.
Many people have questioned why solar PV systems were not included in Section 64. The reason for this was primarily due to the short time line for the project; however, it is hoped that the requirements for solar PV will be amalgamated into Section 64 sometime in the near future. In addition, it should be noted that Section 50 which identifies the requirements for solar photovoltaic systems has been revised to direct Code users to consult Section 64 for requirements such as grounding and power conditioning units.
Photo 1. Free Flow Power testing their proprietary 3-meter SmarTurbine(TM) in the USGS Conte water flume in Turner Falls, MA. Courtesy of Free Flow Power.
The Special Terminology Subsection contains 52 definitions which have been added to provide Code users with an understanding of the new terms associated with renewable energy systems. For example, the following terms have been used throughout Section 64:
Interactive system – which is defined as a power production system such as micro-hydro or wind that operates in parallel with and can deliver power to a supply authority system.
Utility Interactive Inverter– is an inverter that is intended for use in parallel with an electric utility and uses the prevailing line voltage frequency on the utility line as a control parameter to ensure that the renewable energy system’s output is fully synchronized with the utility power. It must be noted that only invertersspecifically approvedfor the purpose, and identified as interactive, shall be permitted in interactive systems.
The General Subsection for Section 64 identifies requirements that apply to all renewable energy systems and includes new rules for overcurrent protection, disconnecting means, wiring methods, grounding and bonding, marking, interconnection methods, etc. Although there are numerous new requirements in the General Subsection, particular attention should be given to the following rules:
Rule 64-010 – Overcurrent protection
A typical renewable energy system can have several sources of supply, each of which could supply electrical energy under a fault condition. As a result, Subrule 64-010(1) requires circuits connected to more than one electrical source to have overcurrent devices located so as to provide overcurrent protection from all sources.
Many renewable energy systems have DC source circuits which can supply fault currents that are more difficult to interrupt than AC fault currents. Consequently, Subrule 64-010(3) requires that overcurrent devices used in any DC portion of a renewable energy power system be specifically approved for the purpose and so marked. As noted in Appendix B, overcurrent devices marked or listed only for AC use should not be used in DC circuits. This note also indicates that equipment used in DC systems such as automotive, marine, and telecommunications is not suitable for use in permanent renewable energy systems.
The output of a utility interactive inverter may be connected to the utility grid by back-feeding a circuit breaker located on the load side of the main service disconnecting means. When overcurrent devices such as circuit breakers are used in this manner, Subrule 64-010(4) requires that the circuit breaker be suitable for back-feed operation. As noted in Appendix B, circuit breakers that are marked “Line and Load” have been evaluated for connection only in the direction marked and as a result are not suitable for back-feed operation.
Rule 64-012 – Disconnecting means
For safety and maintenance purposes, it is essential that a means be provided to disconnect the output of a renewable energy source. As a result, Subrule 64-012(1) requires a disconnecting means be provided to simultaneously disconnect all ungrounded conductors supplied from a renewable energy power supply source from all other conductors in a building or structure. Subrule 64-012(2) requires the disconnecting means be in accordance with Rule 84-024 which specifies the disconnecting means shall:
- be capable of being energized from both sides
- have provision for being locked in the openposition
- be capable of being opened at rated loadbe readily accessible
- etc. (refer to rule for complete list of requirements)
Subrule 64-012(2) also requires the disconnecting means to be located within sight of and within 9 m of the equipment or be integral to the equipment.
In order to provide isolation for safety and maintenance purposes, Subrule 64-012(4) requires a disconnecting means be installed to disconnect equipment such as inverters, batteries, and charge controllers from all ungrounded conductors of all sources.
One of the serious safety concerns associated with interactive, also known as grid tied systems, is the possibility of shock hazards resulting from having two or more sources of supply operating in tandem. In order to address this concern, Subrule 64-012(8) requires that a disconnecting means be provided to disconnect a fuse from all sources of supply if the fuse is energized from both directions. In addition, Subrule 64-012(10) requires that the disconnecting means installed to disconnect the conductors supplied from a renewable energy power source from other conductors of an interactive system, must bear a warning indicating that the terminals on both the line and load sides may be energized when the disconnecting means is open.
Rule 64-014 – Wiring methods
It is essential that the conductors for dc renewable energy sources or supply circuits of a utility interactive inverter installed inside a building or structure have adequate physical protection. As a result, Subrule 64-014(1)(b) requires that these conductors be contained in metal raceways, metal enclosures, or cables with a metal armour or metal sheath. As noted in Subrule 64-014(2), this wiring method shall be provided from the point of penetration of the surface of the building to the first readily accessible disconnecting means.
Rules 64-016, 64-018, 64-020 and 64-022
These rules identify the grounding and bonding requirements for renewable energy systems. As noted in Rule 50-026, these rules also pertain to solar photovoltaic systems. Rule 64-016 indicates which systems are required to be grounded and where the connection to ground shall be located.
Rule 64-018 identifies the requirements that must be satisfied when an ungrounded renewable energy system is installed. It is important to note that Subrule 64-018(e) requires that all ungrounded systems be provided with a ground-fault protection device.
Rule 64-020 indicates that the requirements for grounding electrodes and grounding conductors associated with renewable energy systems shall be in accordance with Section 10. For example, as noted in Subrule 64-020(2)(a) the dc and ac grounding conductors for renewable energy systems shall be sized as required by Rules 10-810 and 10-812. Particular attention should be given to Subrule 10-810(2) which has been revised to allow the dc grounding conductor for a renewable energy system to be sized in accordance with Rule 10-812. As a result, a 6 AWG grounding conductor is permitted for a dc renewable energy system provided it is connected to a grounding electrode conforming to Rule 10-700. Rule 64-020 also outlines the methods that are permitted for connecting the ac and dc renewable energy systems to the grounding conductor. Three very informative diagrams have been added to Appendix B to clarify the intent of these requirements.
Rule 64-022 states that in situations where the bonding connection between the grounding conductor and exposed conductive surfaces is made in the inverter there is the possibility of interrupting the bonding continuity during removal of the inverter or other equipment. Interruption of the bonding continuity could create shock and fire hazards, therefore, Rule 64-022 requires the bonding connection to be made in such a manner that disconnection or removal of equipment will not interrupt the bonding continuity.
Rule 64-026 – Warning notice and diagram
The importance of proper marking for renewable energy systems is critical for the safety of those who are required to work on the premises wiring system as well as first responders. Rule 64-026 identifies the marking requirements for renewable energy systems. For example, where a building or structure with a renewable energy power system is not connected to the grid and is a stand-alone system, Subrule 64-026(1) requires that marking be provided to indicate the location of the disconnecting means and that the structure contains a stand-alone power source. For buildings and structures with both a utility supply service and a renewable energy system, Subrule 64-026(2) requires that the disconnecting means for the two systems be grouped where practicable. In situations where this is not possible, a permanent plaque must be posted on or near each disconnecting means indicating the location of all other service boxes supplying power to the building.
Rule 64-030 –Interconnected system connection
This rule outlines the requirements for the interconnection between the utility interactive inverter and the supply authority. As noted in Subrules 64-030(1) and (3)(a), the interconnection must be in accordance with Section 84 which identifies the requirements for the interconnection of electric power production sources. One of the key requirements for the interconnection to the grid is noted in Rule 84-002 which states that the interconnection arrangements shall be in accordance with the requirements of the supply authority. Further information on this requirement is located in Appendix B. In addition to requiring compliance with Section 84, Subrule 64-030(1) indicates that the output of a utility interactive inverter shall be connected to the supply side of the service disconnecting means. This method of interconnection is recognized by the NEC and will now be permitted by the CEC. Subrule 64-030(3) also permits the output of a utility interactive inverter to be connected to the load side of the service disconnecting means, provided the interconnection is in accordance with Section 84 and is made at a dedicated circuit breaker or a fusible disconnecting means.
The use of renewable energy systems as stand-alone or utility-interactive power systems has steadily increased as the technology and availability of the renewable energy equipment has evolved. The introduction of Section 64 to the CEC will now provide a set of requirements for the safe installation of the electrical systems related to these renewable energies and should further promote their use.
This is only a snapshot of a few of the requirements contained in the General Subsection. I look forward to reviewing Section 64 in further detail in future articles.