Requirements for electrical wiring in hazardous (classified) locations are more restrictive than for wiring in general occupancy types. Sealing is required for conduits and cables installed in Class I, Division 1 and 2...
A review of protection techniques for hazardous (classified) locations reveals descriptive information about each under the “division” and “zone” classification systems. The type of protection technique permitted in a...
In agricultural facilities, voltage gradients can be present in the earth. Neutral-to-earth stray current can affect farm animals and cause significant behavior problems, loss of production and death. These stray currents, or...
Premises electrical distribution systems in outside buildings, structures or facilities are often delivered at high- or medium-voltage levels by the serving utility, depending on the area. The purpose of transformers is to...
In last month’s column, “Dedicated IT Rooms,” I explored the code rules for IT equipment facilities, where isolated grounding circuits and receptacles are often installed to reduce electromagnetic interference in grounding...
In large facilities, it is common for IT equipment to be arranged in a single room or data center. Depending on the extent of the business’ IT needs, an entire building may be constructed for this purpose and designed to meet...
The NEC rules often determine which electrical systems must be grounded, which are permitted to be grounded and which are not permitted to be grounded. The provisions are broken down for each system application. Part II of...
Electrical vehicle use is on the rise, and so is the need for charging infrastructure at residential, commercial and industrial applications. One of the most essential steps for installing electric vehicle supply equipment...
Section 250.53 of the National Electrical Code provides grounding electrode installation rules that apply to grounding electrodes that must be installed and are not typically inherent in construction. The grounding electrodes...
At a grounding class, someone asked how to determine if a standby generator is required to be grounded as a separately derived system. The key to determining this is to verify the type of transfer equipment installed...
In the construction industry, one of the important objectives, aside from completing the project within set timelines, is attaining code compliance and final approval(s). In the electrical field, there are some key factors...
NEC Chapter 5 provides requirements for special occupancies and specific rules for electrical equipment installed and operated in hazardous (classified) locations, such as fuel dispensing facilities, chemical plants and bulk...
With so many alternate (standby) power systems being installed in premises wiring systems today, it is appropriate to visit a few National Electrical Code requirements regarding signage for emergency systems, legally required...
If a large quantity of current-carrying conductors is installed in a raceway outside in an ambient temperature that can reach 125°F, what are the Code requirements regarding applied ampacities? These conductors supply...
Common grounding electrodes installed for alternating current outdoor substation grounding are concrete-encased electrodes, ground rings and ground rods. Section 250.191 requires a grounding electrode system in accordance...
May is Electrical Safety Month. As one of OSHA’s “Focus Four,” it is vital that appropriate attention is placed on attaining and maintaining electrical safety in the workplace, not just in May, but year-round. The National...
Article 100 is the keeper of national electrical code definitions. The NEC Style Manual indicates that if a word or term is used in more than two articles, then it should have a definition in Article 100. Article 100 of the...
Communications systems and equipment installed in buildings must comply with the specific rules given in Chapter 8 of the NEC . Even though these systems typically operate at lower energy levels, improper grounding and...
If circuits are intrinsically safe (IS), the energy is at a low enough level that ignition of an explosive atmosphere will not occur if the circuit is opened, shorted or faulted to ground at the same time a fault occurs at...
The National Electrical Code Section 700.10(A) requires all boxes and enclosures—including transfer switches, generators and power panels that are part of an emergency system—to be marked so they are readily identifiable as...
