COMAR finding on radiofrequency safety and utility smart meters

Abstract

This Technical Information Statement describes Smart Meter technology as used with modern electric power metering systems and focuses on the radio frequency (RF) emissions associatedwith their operation relative to human RF exposure limits. Smart Meters typically employ lowpower (~1 W or less) transmitters that wirelessly send electric energy usage data to the utilitycompany several times per day in the form of brief, pulsed emissions in the unlicensed frequencybands of 902-928 MHz and 2.4-2.48 GHz or on other nearby frequencies. Most Smart Metersoperate as wireless mesh networks where each Smart Meter can communicate with otherneighboring meters to relay data to a data collection point in the region. This communicationprocess includes RF emissions from Smart Meters representing energy usage as well as therelaying of data from other meters and emissions associated with maintaining the meter'shierarchy within the wireless network. As a consequence, most Smart Meters emit RF pulsesthroughout the day, more at certain times and less at others. However, the duty cycle associatedwith all of these emissions is very small, typically less than 1%, and most of the time far lessthan 1%, meaning that most Smart Meters actually transmit RF fields for only a few minutes perday at most. The low peak power of Smart Meters and the very low duty cycles lead to the factthat accessible RF fields near Smart Meters are far below both U.S. and international RF safe-tylimits whether judged on the basis of instantaneous peak power densities or time-averaged exposures. This conclusion holds for Smart Meters alone or installed in large banks of meters.