Chapter 21 Electrical Test and Measurement Equipment 417 Calibration labs are accredited by various organiza- tions. Th ey have calibration standards that must peri- odically be calibrated against standards maintained by NIST (National Institute of Standards and Technology). Th e calibration standards used by a calibration lab, when so calibrated, are considered to be traceable to NIST. When a piece of test equipment has been calibrated, the company receives a certifi cate of calibration. Addi- tionally, each device that has been calibrated receives a sticker indicating the date it was calibrated, who cali- brated it, and when it is next due for calibration. Always check the calibration date before using test equipment. Do not use equipment that is past due for calibration. Th e measurements provided by the equip- ment could be inaccurate. CHAPTER WRAP-UP Whether you are fi eld testing or bench testing, safe prac- tices are critically important when working with elec- tricity. Safety should be a top priority for any electrical technician or responsible employer. Take time to famil- iarize yourself with the safety standards and practices required for a particular system before you start working on it. Electrical technicians must be able to use many elec- trical measurement and testing tools. Learning how to use a variety of testing equipment in a careful and cor- rect manner makes you invaluable for in-house trouble- shooting. Keep your tools properly calibrated to ensure you are taking accurate measurements. Copyright Goodheart-Willcox Co., Inc.