The state of the electrical equipment considering the manufacturers’ instructions, manufacturers’ recommendations, and applicable industry codes, standards and recommended practices.
Another term that is cited in NFPA 70E is “Properly Maintained” —these two words often will have people scratching their heads. And often, developing a legal disclaimer. The term is often a hot topic (pun intended) when discussing the arc flash hazard. Why? Because protective devices such as circuit breakers and relays that have not been properly maintained may not operate as quickly as they should. This means that during an arc flash, a longer duration will result in a greater total incident energy, creating an even greater arc flash hazard.
Calculating the prospective incident energy from an arc flash depends on many variables including the available short-circuit current and the time it takes an upstream protective device to clear the fault. IEEE 1584 – IEEE Guide for Performing Arc-Flash Hazard Calculations provides equations that can be used for this calculation. Graphs of the protective device’s tripping characteristic, known as time-current curves (TCC), are used to predict the time it takes a device to interrupt the arcing short-circuit current.
This may seem like a simple concept, but the question is whether the protective device actually operates as expected. The TCC indicates how fast a device should operate. Operation can depend on other factors, such as whether it was installed correctly, calbirated and maintained properly.
Properly maintained—NFPA 70E
Language about properly maintained electrical equipment can be found in the 2018 NFPA 70E 130.2(A)(4) Normal Operating Conditions. Six criteria must be met for normal operation to be permitted where a normal operating condtion exists.
Normal Operating Condition: Normal operation of electric equipment shall be permitted where a normal operating condition exists. A normal operating condition exists where all of the following conditions are staisfied:
(1) The equipment is properly installed.
(2) The equipment is properly maintained.
(3) The equipment is used in accordance with instructions included in the listing and labeling and in accrodance with manufacturer’s instructions.
(4) The equipment doors are closed and secured.
(5) All equipment covers are in place and secured.
(6) There is no evidence of impending failure.
An informational note also states that the phrase “properly maintained” means the equipment has been maintained in accordance with the manufacturer’s recommendations and applicable industry codes and standards.
Chapter 2 further discusses maintenance requirements for electrical equipment.
“205.3 General Maintenance Requirements: Electrical equipment shall be maintained in accordance with manufacturers’ instructions or industry consensus standards to reduce the risk associated with failure. The equipment owner or owner’s designated representative shall be responsible for maintenance of the electrical equipment and documentation.”
Applicable Codes and Standards
NFPA 70B, Recommended Practice for Electrical Equipment Maintenance, provides details about preventive maintenance for electrical, electronic and communication systems and equipment to prevent equipment failures and worker injuries. In addition, the InterNational Electrical Testing Association (NETA) publishes standards for acceptance and maintenance testing of electrical power equipment.
Caveats and Disclaimers
Some companies have qualified electrical maintenance personnel on staff and may be able to properly maintain electrical equipment. However, many companies don’t have that staffing luxury.
During economic downturns, electrical maintenance can often be a target of budget cuts. Companies may defer maintenance in an attempt to reduce costs. From a financial perspective, this may seem like a good idea. However, from a safety perspective, if an accident occurs due to lack of maintenance, it can become a nightmare.
When performing incident-energy calculations as part of an arc flash risk assessment, the maintenance and condition of protective devices can introduce some uncertainty. Will the devices operate according to their TCCs? To account for this uncertainty, a caveat or disclaimer will almost always be included. The language may be something like: “The results of this arc flash risk assessment are based on the equipment owner or the owner’s designated representative having maintained the electrical equipment in accordance with manufacturers’ instructions or industry consensus standards and that the protective devices operate in accordance with their respective time-current curves.”
Note that the above language is only an example. Consult legal council to develop such a disclaimer.
Don’t Ignore The Elephant in the Room
Proper maintenance and testing of electrical power equipment is important for many reasons. However, when it comes to arc flash and electrical safety, proper maintenance of protective devices can make the difference between minimal or no injuries and the horrific alternative.
If your customer’s electrical system’s maintenance and testing has been ignored or is not up to date, it’s time to catch up. This is something that you cannot afford to ignore.
Based on an article previously published in Electrical Contractor Magazine – September 2015 – Updated for the 2018 Edition
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