The safety and economic benefit of reduced power design densities permitted in the 2014 National Electrical Code

Abstract

This paper describes the effect of a revision to Table 220.12 of the 2014 National Electrical Code which asserts requirements for specifying power chain elements for lighting load that addresses the growing divergence between lighting circuit capacity and the actual load measured. For the first time, the NEC will now permit designers to size in conformity with power density limits in energy codes. This NEC change will result in transformers with lower kVA, reducing arc flash hazard, infrastructure and energy waste. This paper is the first paper to report the significant gains in safety and economy of this code change with two common occupancy applications: a classroom building and a commercial building. This paper also documents the rightsizing opportunity for the other transformers in the building when they are lightly loaded and approaching end of life. Right-sized ultra-efficient transformers reduce electrical infrastructure costs and deliver significant energy savings.