A friend called me recently with some intriguing questions about some electrical work that he was having done at his newly purchased home. The home was built in the mid-to-late 1950s with some electrical work done in various...
Recently, I was asked to explain the reason for the ferrous metal raceway bonding requirements in 250.64(E). Although the National Electrical Code never uses the term “choke effect,” many in the business understand its...
To understand the purpose of ground-detection equipment installed for ungrounded systems, it is best to have a fundamental understanding of ungrounded system performance and the rules that apply to them. Section 250.4(B)...
In the late 1950s and early 1960s, Kodak, then the largest manufacturer of film and cameras, began a product promotion with a series of Christmas-themed advertisements with the tagline “Open me first.” The ad encouraged...
While researching grounding and power quality, the information was divided between how to design the grounding systems of an electrical infrastructure that was optimized to maximize the quality of the electrical power, and...
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...
Jim Dollard has an extensive background in codes and standards. Send questions about the National Electrical Code (NEC) to Jim at codefaqs@gmail.com. Answers are based on the 2020 NEC . NEC arrangement Why are swimming pools...
An electrical contractor emailed me a photo of a feed-through all-in-one 200A 120/240V, single-phase, eight-circuit panelboard with 200A main circuit breaker. It had an auxiliary 2-pole circuit breaker position where up to a...
Communications systems and equipment installed in buildings must comply with the specific rules provided in Article 770 and Chapter 8 of the National Electrical Code (NEC) . Even though these systems typically operate at...
For example, has a limited amount of NM cable been installed in outside locations, such as inside a Type 3R enclosure or inside electrical metallic tubing (EMT) where the EMT has been installed exposed on an outside wall, and...
I recently received a message on LinkedIn from an attorney. That always gets my attention. Many consultants gravitate toward special expert witness work, but I have no interest in it. In court, your client’s attorney will try...
When I was an electrician, I tried to ensure the location and sequence of switches made sense, especially when there were several installed in one location. My goal was that homeowners could understand the installations and...
The grounded conductor at the service provides two essential functions for the premises wiring system. The first is to serve as a current-carrying conductor for the load supplied. Second, it functions as the intentionally...
MAY IS NATIONAL ELECTRICAL SAFETY MONTH The theme for this year’s National Electrical Safety Month is Smart Home. This month, the Electrical Safety Foundation International (ESFI) showcases resources focusing on the...
More efficient lighting within buildings oftentimes doesn’t need as much electricity current flowing to it—and now, the 2020 National Electrical Code reflects that. The list of commercial occupancies within Table 220.12 of...
Requirements that help remove hazards The National Electrical Code includes more than 60 requirements to install a disconnecting means within sight from equipment. These requirements are safety-driven and ensure that workers...
Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC) , Jim will help you solve it. Send questions to codefaqs@gmail.com. Answers are based on the 2020...
I have been asked many times over the years what electrical code other countries use. Does IEC stand for International Electrical Code? Does this affect electrical professionals who only work domestically? I will answer the...
Splices and taps of conductors have been in the National Electrical Code for a long time. The 2020 NEC contains major changes involving distribution blocks, splices and taps, and to understand the reasons for these changes...
