Sometime between the 1925 and 1933 National Electrical Codes , the maximum number of service disconnects changed from one or two disconnects to a maximum of six. I cannot verify the exact edition where the change occurred. I...
New Section 680.4 in Article 680 in the 2020 National Electrical Code enables the authority having jurisdiction (AHJ) to require periodic inspection and testing of swimming pools, fountains and similar installations such as...
Some of the most challenging electrical installations involve healthcare. From major hospitals to clinics in pharmacies, anyone who is not intimately familiar with the intricacies of medical headwalls, major electrical...
July’s article provided a preliminary discussion on cathodic action and dissimilar metal reaction with deterioration of various metals, such as steel water and gas lines. Many of the old metal underground natural gas lines...
Cathodic action and dissimilar metal interaction are phenomena with a long history of recognition in the laws of physics as well as within the National Electrical Code. I first ran across this issue back in the 1970s and ‘80s...
Periodically, a change in the National Electrical Code occurs that is long overdue, such as 2020‘s new Section 300.25. This change may have long-term consequences for electrical contractors, especially if the designer...
Even though the 2020 National Electrical Code was just issued in September 2019 and many states will not adopt the new Code until this year, electrical contractors should be aware of the major changes that will affect most...
at the 2019 NFPA Conference and Expo in San Antonio in June, we had a 17-hour marathon dealing with various code and standards that were up for adoption. I was most interested in the last NFPA document and the adoption of the...
A very knowledgeable electrical contractor in the Phoenix area recently emailed me, stating he was having a National Electrical Code (NEC) discussion with a local electrical inspector. The discussion involved the sizing of...
Electrical engineers, inspectors and contractors, and the National Electrical Code (NEC), have dealt with nonlinear loads for many years. The issue arose in the late 1970s and early 1980s with the increased use of solid-state...
Recently, I received a phone call from an electrical contractor friend who was discussing with an electrical inspector the differences of branch circuits supplying swimming pool equipment versus swimming pool equipment feeder...
Electrical contractors are becoming more involved in the design, installation and servicing of solar photovoltaic (PV) systems for residential, commercial and industrial facilities. While this may be a sideline business for...
Last month’s article covered the general requirements in the National Electrical Code for audio signal processing, amplification and sound equipment in Article 640. One of the most common mistakes many electricians and...
When I was an electrical contractor, I tried to find a specialty where there was less competition and more profit than the normal building wiring. Many ECs doing electrical wiring for dwellings, commercial and industrial...
With the advent of power over ethernet in the 2017 National Electrical Code (NEC) , in Article 393 of the 2014 NEC covering low-voltage ceiling grid power, and other applications dealing with power-limited circuits, there...
Let’s assume a 120/208-volt (V), three-phase service was installed on a building a few years ago and the new owner of the building needs a standby generator for use during power outages. The electrical contractor installs a...
National Electrical Code (NEC) Panel 3 established the new Article 728 in the 2014 NEC. It deals with fire-resistive cabling systems, and it was marginally revised for the 2017 NEC. The article covers the installation of fire...
I have always been fascinated by cables and conductors—sometimes referred to as wires in the National Electrical Code (NEC) and other standards—and the insulation for these cables and conductors, as well as their multiple...
One of my passions, other than the National Electrical Code (NEC), has been fire alarm systems, as covered by NFPA 72, National Fire Alarm and Signaling Code. When I was a licensed electrical contractor in the Phoenix area in...
Both the National Electrical Code (NEC) and NFPA 70E, Standard for Electrical Safety in the Workplace, use the phrase “arcing current.” It is located in 240.87(B)(5) and (B)(6) in the NEC and in many places within NFPA 70E...
