The newest version of NFPA 70E (2015) discusses normal operation of electrical equipment and covers five key elements of what normal means. One of those key elements is that the equipment must be properly installed and maintained (NFPA 70E 130.2(A)(4)). So what exactly does properly installed and maintained mean? How does a company ensure that electrical equipment is in fact safe to operate under normal conditions? The informational note in this same section mentions manufacturer’s instructions and applicable codes and standards as guides. Two of these guides are NFPA 70B Electrical Equipment Maintenance and the MTS/NETA Standard for Maintenance Testing Specifications for Electrical Power Equipment and Systems.
Both of these references have their strengths in making sure your organization has a thorough electrical maintenance program. The key to such a program is that all equipment is being properly maintained in accordance with the equipment manufacturer’s instructions. Well-maintained equipment has a direct effect on the safety of personnel who are tasked to operate electrical equipment. A big piece of the electrical safety pie is an accurate arc flash study, based on the engineering department’s arc-flash studies, which are in turn based upon reliable and appropriately-set protective device tripping times. And do not forget, proper electrical maintenance is imperative for ensuring personnel are in proper PPE when working on or around electrical equipment.
In older facilities, electrical equipment manufacturers may have gone out of business, and older equipment manuals may no longer be available. In cases like these, resources are available outside of manufacturer’s instructions. Two of these resources, mentioned earlier, are NFPA 70B, and the NETA MTS Manual. Your organization can choose which guideline to follow, and in your internal procedures, can include how to practically apply the chosen standard’s guidelines. Your maintenance and inspection process could, and possible should, include a variety of available electrical resources to have a well-rounded, thorough approach. The two standards previously mentioned cover many types of electrical equipment, and describe testing, inspection processes, and in some cases, active monitoring for each type. Both standards do that from different points of view. We’ll look at just two topics to show what each standard offers.
NFPA 70B (2013 edition) does a great job covering the topic of grounding in Chapter 14. Section 14.1 defines the myriad of words used when discussing grounding and/or bonding, such as “counterpoise,” “down conductor,” and “grounded” vs “grounding” conductor. Anyone familiar with the National Electrical Code’s Article 250 should be very familiar with these often confused terms. The chapter continues in 14.2 to provide symptoms and even causes of inadequate grounding. Section 14.3 addresses grounding system inspections, testing, and monitoring, and finally Section 14.4 ends with “Solutions to Inadequate Grounding.” In the final section, 14.4.1 provides four basic ideas for improving grounding at a jobsite, covering basic tasks such as cleaning, tightening, and testing connections, replacing or repairing damaged parts, using the correct size grounding conductor(s), and even using soil enhancement material if necessary, which is often applied at cell antenna sites for lightning protection.
In comparison, the NETA/MTS 2015 guide on grounding starts in section 7 – Inspection and Test Procedures. This section includes visual and mechanical testing of grounds, and provides specific guidance on which tests to follow. The section goes on to recommend using the manufacturer’s torque requirements or the provided torque requirement table in the latter section of the NETA standard. It continues by addressing a series of electrical tests to perform, with guidelines of when to dig deeper when questionable results arise. One specific test shows when it is necessary to investigate point-to-point resistance values during bolted connection resistance testing.
Similar comparisons can be made in the breaker testing procedures in each manual. For example, the NETA-MTS book gives a step-by-step reference for molded-case breakers. First on the testing list is bolted connection impedance testing, followed by insulation-resistance testing; long-time, short-time, and ground-fault pickup testing; and time delay testing via current injection. The procedure continues with a comprehensive circuit breaker program, including reference charts to follow for specifications that may be missing from manufacturers who may have gone out of business. The end result of the NETA testing method is a well-maintained and documented molded-case breaker maintenance program.
Section 11.10 of NFPA 70B addresses Low Voltage circuit breakers, both molded-case and power circuit breakers. 70B gives excellent documentation of the testing program, referencing many industry standards that are commonly accepted as Best-Practice. The references include NEMA AB4 Guidelines for Inspection and Preventive Maintenance of Molded-Case Circuit Breakers Used in Commercial and Industrial Applications, as well as ANSI/IEEE C37.13, ANSI/NETA ATS, and ANSI/NETA MTS. NFPA 70B gives detailed guidance on trip test times, coil pickup tolerances, and more, but one may get lost in the manual’s wordy guidelines, unlike the step-by-step approach of NETA/MTS-2015. If you are one who needs an education on what all is involved in a typical circuit breaker testing program, NFPA 70B is definitely the book to provide this knowledge. It covers almost four full pages in small print of the Low Voltage Circuit Breaker testing process.
Either manual will certainly enhance your system’s electrical maintenance program. E-Hazard suggests that you look at both books, along with other resources from IEEE and ASTM to be certain that “normal” operation of electrical equipment has the highest possible chance of being “normal.” With that said, we at e-Hazard still suggest, at a minimum, a base layer of PPE any time you or your staff are interacting with electrical equipment. These electrical safety training tips are provided in detail in our Low Voltage, High Voltage, and OSHA 1910.269 classes.