虽然照明制造商和独立测试实验室通常遵循IES发布的程序，在受控实验室条件下测试灯具，但在现场进行的用于确认预测性能的测量可能会受到多种因素的影响。在实验室条件下，应注意控制光度测量条件的精度和准确度，包括灯具方向、测试距离、环境温度、电源和调节，以及选择最佳稳定性和电弧管几何形状的灯具。在现场，在操作和测量条件下，这种水平的控制和精度几乎是不可能的，对安装的光度性能进行的测量可能会偏离预测的性能水平。 本文件确定了适用于户外HID灯具（汞蒸气、金属卤化物和高压钠）和低压钠照明设备的许多潜在因素，这些设备使用芯线和线圈镇流器，用于当代灯具瓦数指定。本文件概述了可能导致室外HID和低压钠灯及灯具的计算和测量照度及亮度值之间存在差异的因素。它没有提供解决方案，也没有量化可能遇到的所有可能变量。

While lighting manufacturers and independent testing laboratories generally follow IES published procedures for testing luminaires under controlled laboratory conditions, measurements made in the field to confirm predicted performance can be influenced by a variety of factors. Under laboratory conditions, care is exercised in the control of the precision and accuracy of the photometric measurement conditions, including luminaire orientation, test distances, ambient temperature, electrical supply and regulation, and selection of lamps for optimal stability and arc tube geometry. In the field, this level of control and accuracy in operating and measurement conditions is seldom possible, and measurements made of installed photometric performance can deviate from predicted performance levels. This document identifies many of the potential factors that apply to outdoor HID luminaires (mercury vapor, metal halide, and high pressure sodium) and low pressure sodium lighting equipment utilizing core and coil ballasts for contemporary lamp wattage designations. This document outlines factors that can cause differences between calculated and measured illuminance and luminance values of outdoor HID and low pressure sodium lamps and luminaires. It does not offer solutions, nor does it quantify all of the possible variables that might be encountered.