CODE CITATIONS Article 110 Requirements for Electrical Installations Article 230 Services Article 240 Overcurrent Protection Article 310 Conductors for General Wiring Article 430 Motors, Motor Circuits, and Controllers Article 450 Transformers and Transformer Vaults Article 695 Fire Pumps Warning si
A voltage sag originates at the startup of a motor. if the voltage drops quickly and steadily increases, you have sag. Some signatures of power quality (PQ) phenomena are difficult to discern from the megabytes of data that PQ monitors can produce in a relatively short time.
(Please refer to ELECTRICAL CONTRACTOR magazine for referenced figures). On a single-phase circuit, the origin of a voltage sag is usually downstream if the neutral-to-ground voltage significantly increased during the sag.
For the past three years, this column has covered a different power quality-related topic each month. Now that most of the major areas have been covered, it seems as though it is time to use a different approach.
*Please see Electrical Contractor magazine for figure references.* 210.52(A) General Provisions Provisions stipulating the placement of receptacle outlets for dwelling units are covered in 210.52(A) through (H). Last month’s “In Focus” covered both paragraphs and the fine print note in 210.52.
Whenever energized electrical equipment is being examined, serviced, maintained or adjusted in any way, there is always the potential for an electrical explosion to occur, resulting in injury to the electrical worker and damage to the equipment.
• Please refer to ELECTRICAL CONTRACTOR magazine for referenced illustrations. 210.8(A) Dwelling Units Receptacles installed in certain locations must have ground-fault circuit-interrupter (GFCI) protection for personnel.
In a recent discussion about the virtues of power quality (PQ) monitoring with some less-than-knowledgeable business people, the point was raised that, “Why bother to figure out whose fault it is if you can’t fix it?” I responded to this comment by showing them some of the latest software tools avai
The upstream sags and interruptions caused by faults on the electric utility system are often blamed for being the root of all evil, yet studies have shown that most power quality (PQ) problems originate within the facility itself, as indicated from the following sources: