The project is a 3,000 square foot 1-story new office building. The requirements of this prerequisite are to comply with the mandatory provisions (sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4) of ASHRAE/IESNA Standard 90.1-2004 and the prescriptive requirements (sections 5.5, 6.5, 7.5, and 9.5) of ASHRAE/IESNA Standard 90.1-2004. ASHRAE/IESNA Standard 90.1 2004 Section 8.4.1.1 states "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The exception we would like to take is as follows: We meet all the other requirements of this prerequisite for minimum energy efficiency requirements. Our design is approximately a 2.9% voltage drop, which meets the latest edition of the National Electric Code 215-2(A)(2) FPN#2 which allows between 3-5% voltage drop. The cable size is parallel 500 MCM. To meet the 2% requirement, the cable size would be increased to parallel 750 MCM. This is a significant cost increase to the project without gaining any energy savings. Will the 2.9% voltage drop be acceptable to use?
The project is requesting a relaxed voltage drop requirement for feeder conductors. ASHRAE/IESNA Standard 90.1-2004 is the referenced standard for EAp2 for LEED. The purpose of this standard is to provide minimum requirements for the energy-efficient design of buildings except low-rise residential buildings. This Standard is explicit in the requirement as stated in Section 8.4.1.1: "Feeder conductors shall be sized for a maximum voltage drop of 2% at design load." The fundamental purpose of the National Electrical Code (Section 90.1(A) and (B)) is to provide for practical safeguarding of persons and property, and contains provisions that are necessary for safety. In keeping with the purpose of the ASHRAE/IESNA Standard 90.1-2004, its requirements are more stringent than the allowances in the National Electrical Code. Therefore, the project must meet the requirement per Section 8.4.1.1 of the Standard in order to comply with this prerequisite. Applicable Internationally.