[Code of Federal Regulations] [Title 10, Volume 3] [Revised as of January 1, 2001] From the U.S. Government Printing Office via GPO Access [CITE: 10CFR435.106] [Page 549-553] TITLE 10--ENERGY CHAPTER II--DEPARTMENT OF ENERGY PART 435--ENERGY CONSERVATION VOLUNTARY PERFORMANCE STANDARDS FOR NEW BUILDINGS; MANDATORY FOR FEDERAL BUILDINGS--Table of Contents Subpart A--Voluntary Performance Standards for New Commercial and Multi- Family High Rise Residential Buildings; Mandatory for Federal Buildings Sec. 435.106 Electric power and distribution. 6.1 General 6.1.1 This section contains minimum requirements for all building electrical systems, except required emergency systems. 6.1.2 A building shall be considered in compliance with this section if the minimum requirements of section 6.3 are met. 6.2 Principles of Design 6.2.1 Electric Distribution Systems 6.2.1.1 Transformers and generating units shall be sized as close as possible to the actual anticipated load (i.e., oversizing is to be avoided so that fixed thermal losses are minimized). 6.2.1.2 Distribution of electric power at the highest practical voltage and load selection at the maximum power factor consistent with safety shall be considered. The use of distribution system transformers shall be minimized. 6.2.1.3 Tenant submetering can be one of the most cost-effective energy conservation measures available. A large portion of the energy use in tenant facilities occurs simply because there is no economic incentive to conserve. 6.3 Minimum Requirements 6.3.1 Electrical Distribution System 6.3.1.1 All commercial or multi-family high rise residential buildings, having designed connected electric service over 250 kVA, shall have electrical energy consumption check metered on the basis of usage category or tenant occupancy, depending on conditions defined below. For buildings that are occupied by multiple tenants, the metering shall be per tenant, if the tenant has a connected load of 100 kVA or more. HVAC and service hot water systems, shared among tenants, need not meet this requirement but shall be separately metered. 6.3.1.2 The electrical power feeders for each facility for which check-metering is required shall be by tenant and shall be subdivided in accordance with the following categories: 6.3.1.2.1 Lighting and receptacle outlets; 6.3.1.2.2 HVAC and service water heating systems and equipment; and 6.3.1.2.3 Special occupant equipment or systems of more than 20 kW, such as elevators, computer rooms, kitchens, printing equipment, and baling presses. 6.3.1.2.4 Exception to Section 6.3.1.2: (a) 10% or less of the loads on a feeder may be from another usage category. 6.3.1.3 The power feeders for each category shall contain portable or permanent submetering prior to or within any primary or secondary distribution panels. Such provisions shall include a separate compartment or panel of adequate size and design to house the necessary voltage and current transformers. An accessible means of attaching clamp-on meters or split-core current transformers shall be provided. 6.3.1.4 The locations of these points of measurement may be central or distributed throughout the building, as [[Page 550]] appropriate to the layout of the building. A minimum arrangement shall provide a safe method for access to the enclosures through which feeder conductors pass, and have sufficient space to attach clamp-on or split- core current transformers. These enclosures may be separate compartments or combined with electrical cabinets serving another function. Enclosures so furnished shall be identified by available measuring function. A preferred arrangement would include kWh meters and demand registers, or a means to transmit such information to a building energy management control system. 6.3.1.5 In multiple-tenant buildings, where designed connected electrical service is over 250 kVA, each tenant space having a total connected load of more than 100 kVA shall have provision made to permit check-metering of the total tenant load. If the building is served by a common HVAC system, the HVAC loads need not be check metered for each tenant. 6.3.2 Transformers 6.3.2.1 All permanently wired transformers, that are part of the building electrical distribution system, except utility-owned transformers, shall be selected to minimize the combination of no-load, part-load, and full-load losses, without compromising the electrical system operating and reliability requirements. 6.3.2.2 If the total capacity of the transformers exceeds 300 kVA, a calculation of total estimated annual operating costs of the transformer losses shall be made. This calculation shall be based on estimated hours of transformer operation at projected part-load and full-load conditions, and the associated transformer core and coil losses. If appropriate data for projecting this calculation is unavailable, use Form 6.3-1 ``Transformer Loss Calculation Estimate'' as a basis for making the estimate. The calculations made in accordance with this section shall be used to compare among types of transformers and configurations available to the designer to balance energy costs with necessary operating flexibility, reliability (redundancy), and safety. The projected annual energy costs for the losses of the selected arrangement shall be retained as part of the electrical design documentation. [[Page 551]] [GRAPHIC] [TIFF OMITTED] TC04OC91.207 6.3.3 Electric Motors 6.3.3.1 All permanently wired polyphase motors of 1 hp or more serving the building, shall meet the requirements of this section. Motors expected to operate more than 500 hours per year shall have a minimum acceptable nominal full-load motor efficiency no less than that shown in Table 6.3-1. 6.3.3.1.1 Table 6.3-1 applies to motors having nominal 1200, 1800, or 3600 RPM; with open, drip-proof, or TEFC enclosures. Other motor types are exempted from the minimum efficiency requirements of these standards. 6.3.3.1.2 Motor efficiency ratings shall be based on a statistically valid quality control procedure conforming [[Page 552]] with ANSI/IEEE 112-1984, Test Method B (Dynamometer) using NEMA MG 1- 1987 (MG 1-12.54 and MG 1-12.55) for motors below 500 hp. For motors 500 hp and above, ANSI/IEEE 112-1984, Test Method B or Method F (Equivalent Circuit Calculation), shall be used. 6.3.3.1.3 Values listed in Table 6.3-1 are nominal efficiencies. Minimum motor efficiencies shall not be less than the corresponding values provided in NEMA MG 1-12.54. [GRAPHIC] [TIFF OMITTED] TC04OC91.208 6.3.3.1.4 Motor efficiency shall be tested using a statistically valid quality control procedure conforming with the IEEE 112A, Test Method B (1978) (Dynmometer) fan motors E below 500 hp, or Test Method F (1978) (Equivalent Circuit Calculation) based on no-load measurements for motors 500 hp and larger. 6.3.3.2 Motor nameplates shall list the minimum and the nominal full-load motor efficiencies and the full-load power factor. 6.3.3.3 Full-load motor power factor for three-phase motors can be calculated from nameplate data by Equation 6.3-1: % Power Factor=(hp x 745 x 100)/(nominal efficiency x full-load amps x rated voltage x 30.5). Equation 6.3-1 6.3.3.4 Motor horsepower rating shall not exceed 125% of the calculated maximum load being served, or the next larger standard motor size if a [[Page 553]] standard rating does not fall within this range. 6.3.4 Operation and Maintenance of Electrical Systems 6.3.4.1 The designer shall specify that building owners be provided with written information that provides basic data relating to the design, operation, and maintenance of the electrical distribution system for the building. This shall include: 6.3.4.1.1 a single-line diagram of the ``as-built'' building electrical system; 6.3.4.1.2 schematic diagrams of electrical control systems (other than HVAC, covered elsewhere); 6.3.4.1.3 manufacturers' operating and maintenance manuals on active electrical equipment; and 6.3.4.1.4 the Transformer Loss Calculation Estimate if required by Section 6.3.2.2.