For a 1,200-ampere (A), three-phase, 120/208-volt (V) service, can I run three sets of 500 kcmil underground from the transformer pad to the main 1,200A switch, or does it have to be 600 kcmil?
Article 240 in the National Electrical Code (NEC) provides general requirements for overcurrent protection and overcurrent protective devices. When sizing conductors, the rating of the overcurrent device must be considered.
There are many reasons for motor failures, such as overloading, bearing failures, rotor failures, worn shafts, and short circuits or ground faults within the motor windings, and contaminants that may enter the motor, causing short circuits or overloading.
A faithful reader of ELECTRICAL CONTRACTOR asked how to design and install high-voltage feeders according to the 2008 National Electrical Code (NEC). He requested that I write an article pertaining to such an installation.
Consider the fable about crying wolf. False alarms have the same effect in reducing the credibility of alarms. Individual experiences with home smoke alarms that keep going off from cooking develops a negative culture of response to real emergencies.
The 2008 National Electrical Code (NEC) includes a new definition covering “Intersystem Bonding Termination” and a total rewrite of Section 250.94 covering the requirements for installing a bonding connection point for communications systems.
A contracting firm I work for is bent out of shape over the new revised Section 210.4(B) and (D) in the National Electrical Code (NEC). The firm, plainly speaking, said this was going to require time to police the trimming out of a panelboard.
Article 220 Branch Circuit, Feeder, and Service Calculations; Article 240 Overcurrent Protection; Article 250 Grounding and Bonding; Article 404 Switches; Article 700 Emergency Systems; Guide Information for Electrical Equipment Directory (White Book) published by Underwriters Laboratories Inc.