2020 National Electrical Code
2020 National Electrical Code: Article 330 Metal-Clad Cable Type MC
Metal-Clad (MC) Cable is used every day in the electrical industry. The true conduit benders hate it. The value engineering people love it. MC Cable is really a great product, has a wide variety of uses, and can be installed to look good. Let’s take a closer look at this industry workhorse: Metal-Clad Cable.
MC Cable Definition
MC Cable, by most common definition, is a factory assembly of one or more insulated circuit conductors enclosed in an armor of interlocking metal tape or a smooth or corrugated metal sheath. The smaller cables should be unsheathed by using an armored cutter like the famous “Roto-Split”. The fittings must be listed and identified for use. If the manufacturer provides anti-short bushings, they can be used. The bushings are not an NEC requirement since the listed MC connectors provide the conductor protection from sharp edges.
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Why Do Some Code Sections Differ from My Copy of the NEC?
Have you ever compared your NFPA 70 book with a colleague and found that there were differences, though both books were the same edition of the NEC? We know that we receive a new edition of the NEC every three years, but how does the Code change between cycles?
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Sizing Equipment Grounding Conductors (EGC) Table 250.122: What’s New in the 2020 NEC?
If you turn to Section 250.122 in your NEC, you find information that has assisted electricians sizing equipment grounding conductors (EGC) for longer than most electricians have even been twisting wire.If you were on the job in 1968, you would have turned to Table 250.95 in your NEC for this information instead of Table 250.122, but the information was essentially the same.In 1968 you also would have found that an ungrounded (hot) branch circuit conductor protected by a 6000-amp overcurrent device required no less than a 1200 kcmil aluminum equipment grounding conductor… assuming you were using an aluminum equipment grounding conductor. That information remained unchanged for 50 years. But as the saying goes, “All good things must come to an end.”
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Electrical Burial Depths and Procedures
Underground electrical installations can save labor hours, material costs, and provide protection to the installation. Sometimes going underground is the only logical path to get service from one point to another whether new construction or remodel work. Overall, there are not many electrical projects that don’t require a little digging in the dirt at some point. Let’s dust off the National Electrical Code (NEC) and review some Code pertaining to burial depths and standard operating procedures.
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Service Disconnects: How Many and Where to Put Them. What’s New For 2020?
NEC Section 230.71. Six Switches or Circuit Breakers in One Enclosure
Since the 1937 edition of the NEC, the service disconnecting means used to isolate a building’s premises wiring from the utility provider’s conductors has been allowed to consist of as few as one, but as many as six switches or sets of circuit breakers.A veteran electrician would tell you that requirement (or permission, depending on your perspective) means six throws of the hand can be used to control all power on the property. Our veteran electrician is correct – if there is one electrical service on the property.
