NFPA 70B Maintenance Intervals and Frequencies

NFPA 70B Maintenance Interval PDF

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It’s important to be redundant in the objective of NFPA 70B; “the objective of an equipment maintenance program is to maintain safe operation and production while reducing or eliminating system interruptions and equipment breakdowns”.  Breaking-down means lost time of production or, even worse, injury or loss of life.  With that said, NFPA 70B identifies three types of monitoring the health of the devices; one, the application of testing/inspection maintenance (we’ll get to that), two, continuous monitoring, which is based-upon actual conditions as they happen, and three, predictive monitoring, which is the use of software or “advisors [to] analyze and interpret data and provide recommended maintenance actions before alarm set points are reached”.  (NFPA 70B A.9.1.1). Continuous monitoring and predictive technologies are obviously advanced methods of overseeing the health of an electrical system and potentially involve a lot more than internal/third party testing individuals.  As an example, consider the following:

How much does Continuous Monitoring cost?

For basic dynamic monitoring of electrical devices that merely detect faults, a basic system would cost approximately $50 to $200 per device per year.  This would involve hardware installation of the devices that will vary from $200 to $5,000 per device, depending on the device type, such as vibration sensors, CTs, etc).  For the software that monitors the integrated hardware on the devices, the cost can range from $5,000 to $50,000 per year, depending on how it’s displayed, integrated, how many users have access and other factors.  For advanced monitoring, which would have predictive abilities, one can be expected to spent a bit more.  In the end, with a site with 400 electrical devices, you might spend around $80,000 per year in addition to the hardware integration.  For advanced predictive monitoring, one can expect to spent well over $1,000,000, depending on sophistication.  Obviously, this is well-beyond the capabilities, and cost-benefit, of most entities.

NFPA recognizes these continuous monitoring and predictive methods and are permitted to be used when determining maintenance intervals.  In the end, maintenance intervals are used to approach the upkeep and monitoring of electrical devices in a standardized manner.  Therefore, when one has dynamic (real-time), especially when combined with predictive maintenance, is the highest level of maintenance.  That being said, there still needs to be a maintenance plan, because the dynamic information supplied by these systems can change the intervals, but not replace them.

NFPA 70B Maintenance Intervals & Inspections

Maintenance Intervals are used to plan the testing/inspections of critical equipment and need to be based-upon some sort of time-system; that is, a calendar method (most common) or cycle count, hours of operation (like an engine) or similar counting methods.  The intervals, in general, are also modified, as stated, based-upon the importance of the device, the condition rating of the device, and of course, the type.

Is an IR scan every year all you need?

Many times, especially when I’m engaged with an electrical contractor that has received a request from the customer to be NFPA 70B compliant, I hear that you just have to “IR scan the equipment every year and you’re ‘good to go”.  Not only is this incomplete, it is erroneous.  Thermographic surveys (IR scans) are a requirement of NFPA 70B, but is one of over one hundred and a brief moment should probably stated on IR scans.  We know why an IR scan is favored by end-users and contractors alike; it doesn’t require an outage.  However, besides the fact that it’s not complete compliance to NFPA 70B, the following issues are noted:

1. External or natural internal temperatures interfere with any analysis, such as a transformer,
2. Some electrical faults don’t show a material difference in temperature,
3. Polished metal can distort IR measurements, and
4. There is no direct quantitative information to give direction if there is a deficiency. 

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How to Keep Track of Maintenance Intervals?

It should be obvious now that keeping track of what devices are included in a particular condition, environment and inspection state requires a tremendous amount of platform organization.  Additionally, when an audit does occur, the simple task of reporting on what was done, by whom and when is quite daunting.  This is were the unwritten rule of an EEOS software system comes into play.  High quality systems, such as Gimba or customized IBM Maximo, hold the information cleanly and, in some cases, are made for the field technician to easily make corrections as they are seen in the field.

As an aside, when one considers all the methods employed for maintaining all the different equipment within an electrical distribution system or transmission system, there always seems to be an impressive library of binders in the office of the facility manager.  This is due to the various manufacturers’ specific maintenance protocols and the changes in a facility’s compliance.  Again, without the presence of an EEOS system or some sort of CMMS system that is custom designed, it is a daunting task to organize all the various tasks; from meter reading to inspection records to engine manuals.

Chapter 9.2.2 – The Intervals

As it pertains to adjustments to Table 9.2.2 Frequency of Maintenance, NFPA 70B has a few added notes as follows:

9.2.2.1

“The intervals in Table 9.2.2 shall only be required if referenced by a specific section in another chapter.”

9.2.2.2

“The maintenance interval for electrical equipment shall be permitted to be altered based on the potential risk to personnel or facility operations due to a failure of the equipment to operate as expected”

9.2.2.3

“Any deviations from the maintenance intervals described in Table 9.2.2.2 to extend the maintenance interval and the justification for the deviation shall be documented in the EMP”

Although I wasn’t present at the discussion-table when this was written, it seems to be that 9.2.2.3 is the only point in this small section that creates an allotment for equipment that is potentially not energized and in storage, specially manufactured devices that do not quite fit into the categories noted by NFPA 70B or was an exception created to allow for unknown circumstances.  Regardless, it is clear that denoting the exception in the EMP is the cover-all.  Again, any divergence from the NFPA 70B maintenance intervals must be justified within the EMP.

In summary, Chapter 9 gives fairly clear guidance on maintenance intervals, with the caveat of failures, manufacturers recommendations and environmental notations that can adjust the intervals.  With this being said, the EMP being properly maintained is point that cannot be ignored.  Most importantly, especially with the view of all the different types of devices and maintenance activities, the central theme is having a system that will manage all these protocols, documents and revisions, especially the ability to enact changes and edits to conditions in the field, all the while being able to audit historical changes.  This, of course, lends itself to having a robust EEOS like a customized IBM Maximo or Gimba Technology platform to track all these various activities.  It would simply be impossible to do so with ‘paper and pen’ ledgers, Excel spreadsheets or other former methods that reflected a time that was less complicated. 

Why NFPA 70B, Why Now?

A question that often arises is ‘how did this become so complicated and why wasn’t this complexity addressed decades ago’.  The reason is simple; devices and distribution/transmission systems have become more complicated.  From transformers to relays, we have seen a massive increase in the complexity and variety of device types as the years move forward.  Additionally, devices that were manufactured in the 1950s are still in service today (and in some cases, even further back).  Therefore, individuals who are responsible for the management and upkeep of said inspections, maintenance and inventory management have the task of making sure who did what, what was done and what equipment was it done to, must have an EEOS or auditing and tracking is near impossible.

NFPA 70B Physical Condition of Equipment 9.3.1

The condition of equipment, in addition to its environment, type and where it is on its maintenance interval, is of utmost importance.  There are three main categories of physical condition of equipment cited by NFPA 70B.  They are Condition 1, 2, and 3.  It is rare to have a category of this nature expressed within a software environment or physical, manual method, so choosing the correct application for evaluation is important.  As it pertains to Condition 1, the following criteria are noted by NFPA 70B 9.3.1.1, and I quote:

1.     The equipment appears in like new condition,
2.     The enclosure is clean, free from moisture intrusion, and light,
3.     No unaddressed notification from the continuous monitoring system has occurred,
4.     There are no active recommendations from predictive techniques, and
5.     Previous maintenance has been performed in accordance with the EMP.

Again, the EMP is the guiding document that all other factors fall into.  This section also refers back to continuous monitoring systems and predictive maintenance guidance; a very costly integration with limited cost-benefit, unless the supported facility has such a high revenue that demands integration and upkeep of said system, as well as the unavailability of individuals and their cost to physically and electromechanically test the equipment.  Lastly, although vague, the standard of “appears in like new condition” as well as “enclosure is clean, free from moisture intrusion, and light”, can be understood as environmental considerations.  There are breakers that are fifty years old that “look like new”, but some that are less than one year, due to the environment, look quite dirty.  This is a preventative measure that NFPA 70B stresses, but is redundant from environmental concerns.

NFPA 70B Conditions

As it pertains to Condition 2, the following are noted from 9.3.1.2 and I quote:

1. Maintenance results deviate from past results or have indicated more frequent maintenance in accordance with manufacturer’s published data.
2. The previous maintenance cycle has revealed issues requiring the repair or replacement of major equipment components,
3. There have been notifications form the continuous monitoring system since the prior assessment, and
4. There are active recommendations from predictive techniques.

Condition 2 has a focus on the testing results (or results from mechanical or visual inspections) that deviate from accepted norms.  In other words, if the handle on a switch is exercised and it’s “a little rough and clicks oddly when moved”, in contract to the last time, this would be an example.  Additionally, if the oil sample pulled from a transformer shows contents that are beyond the tolerances, this would be an additional example.  There is no reference to a missed testing/inspection interval; that is, if a visual inspection was missed, or your doing it late, this does not move the device into Condition 2, if it was at Condition 1.  Frankly, most advisors place devices into Condition 1 or 2, as Condition 3 points towards failure and who is going to allow a critical device to sit in an “unmaintained condition for two successive maintenance cycles” condition?  Lastly, the points 3 and 4 again refer to predictive techniques or continuous monitoring systems, leading someone to wonder if one of the contributors to NFPA 70B sits on the board of a predictive maintenance integration company.  However, the use of an EEOS that would give access to manufacturers’ recommendations and the management of all these aspects mentioned, is the clear path to having active data; a necessity, frankly.

With respect to Condition 3, the following are noted in NFPA 70B 9.3.1.3 and I quote:

1. The equipment has missed the last two successive maintenance cycles in accordance with the EMP,
2. The previous two maintenance cycles have revealed issues requiring the repair or replacement of major equipment components,
3. There is an active or unaddressed notification from the continuous monitoring system, and
4. There are urgent actions identified from predictive techniques.

Condition 3 is meant to be an alert for the facility manager and other supervisory roles.  Ignoring the “unaddressed notification from the continuous monitoring system” and “urgent actions identified form predictive techniques”, it is a “call to action” for the maintenance department.  Point 4 is especially vague, due to the fact that “predictive techniques” also includes advisors, whom, due to incentives, may recommend urgently replacement, repair, reconditioning, etc of equipment that may or may not have to do with imminent failure or personal safety.  However, this does mean, for example, if visual inspections are identified as a monthly interval by the internal EMP and three months go by without the visual inspection taking place, this device should be placed into Condition 3.  Therefore, I cannot stress enough the importance of a well-crafted EMP, as well as the considerations of labor that it implies, especially when third-party vendors are a part of the equation.  Lastly, having an EEOS like Neptune or Gimba Technology will allow the party to avoid redundant activities, as one can include other regulations, such as OSHA-mandated operational checks on eye wash stations, etc to be included in the visual inspections.

Non-Serviceable Equipment – Chapter 9.3.1.4

Referring back to NFPA 70B 8.7.1.3 Non-Serviceable, NFPA 70B 9.3.1.4 discusses equipment that “has a problem that is detrimental to the proper electrical or mechanical operation of the equipment”.  This means that if there is a breaker that is stuck or a relay that is not responding, this is non-serviceable.  Does this mean that a transformer that is leaking oil is “detrimental”?  The section is not clear, but we advise on the side of caution.  However, there is most certainly some room to become more specific in this standard, understanding that the variety of issues that the wide-array of electrical equipment would make NFPA 70B rather cumbersome. 

NFPA 70B notes that said equipment, exhibiting these “detrimental” characteristics be corrected before returning to use and that no person who is unqualified should not be allowed access to said equipment.  This, of course, is entirely reasonable and understandable.

Criticality Condition of Equipment – Chapter 9.3.2

To add to the details of equipment assessment and issues that may arise, NFPA 70B lends direction to the Code A.9.3.2 when addressing equipment that poses the risk of failure.  A significant amount of direction is given to the persons that should conduct, or be responsible, for assessment.  Below is the details of said assessment team from the Code A.9.3.2:

“A criticality assessment team should be comprised of personnel who are familiar with the electrical equipment, safety requirements, operational capabilities, potential impact of downtime, required maintenance activities, and business priorities.  The team can include external expertise when needed. Some examples of the type of personnel to include in a criticality assessment include the following:

1. The electrical foreman or superintendent,
2. Production personnel thoroughly familiar with the operation capabilities of the equipment and the effect its loss will have on quality and productivity,
3. The senior maintenance individual who is generally familiar with the maintenance and repair history of the equipment or process,
4. A technical individual knowledgeable in the theoretical fundamentals of the process and its hazards (e.g. in a chemical plant, a chemist; in a mine, a geologist),
5. A safety engineer or the individual responsible for the overall security of the plant and its personnel against fire and accidents of all kinds.

The team should review the entire plant or each of its operating segments in detail, considering each unit of equipment as related to the entire operation and the effect of its loss on safety and production.  The purpose of the review is to identify failure modes and their cause and effect.

There should be objective criteria consistently used to evaluate all equipment to make a clear determination in establishing whether a system is critical and in having the proper amount of emphasis placed on its maintenance.  The determination of critical parts should be the responsibility of the electrical foreman or superintendent on the team.

The entire team should consider each alarm in the system with the same thoroughness with which they have considered the shutdown circuits.  A critical alarm should be characterized by its separate sensing device, a separate readout device, and separate circuitry and power source.  The maintenance department should thoroughly understand the critical level of each alarm.  The critical alarms and their significance should be distinctly marked on drawings, in records, and on the operating unit.  For an alarm to be critical does not necessarily mean that it is complex or related to complex action.  A simple valve position indicator can be one of the most critical alarms in an operating unit.”

Understandably, there is a tremendous amount of compliance in this section that may seem daunting at first.  However, you will find that most people operating in an electrical maintenance role understand that when a relay is flashing “error” or a valve position is out of order, there is an issue to address.  The main point in this area is that the EMP addresses clearly the role and hierarchy that is to deal with said issues.  It is also made clear in 9.3.2.1 that Criticality Condition 1 and 2 are assigned when there is an issue that may cause failure, but personal injury is not probable.  Criticality Condition 3 is assigned when the failure of the device or system could cause injury to individuals.  In one’s mind, although not clearly stated, a nuisance tripping breaker within a lineup that has an incident energy rating of 120 Cal/cm2.  In this case, I wouldn’t want to be around it either.  

Operating Environment Condition of Equipment Chapter 9.3.3

This section pertains to the environment in which the equipment is placed.  Condition 1 and 2 pertain to equipment that is operating in the environment that it was meant for; think outdoor-rated pad-mounted transformer.  The Condition 3 refers to “harsh” environments, such as chemicals or extreme conditions.  Both environment and criticality considerations lend oneself to believe that further notations will be issued by NFPA, as Conditions 1 and 2 in both categories have little details on what separates the two. 

NFPA 70B Maintenance Intervals Summary 

The importance of Chapter 9 cannot be understated; it is the cornerstone of proper compliance to NFPA 70B as well as the health of the equipment and the individuals working in the environment.  With a properly formed EMP (Electrical Maintenance Plan), the protocols, testing intervals and individuals responsible for the periodic maintenance (and types of maintenance) are clearly stated.  Mostly importantly, the organizational format of all these various documents and procedures lend oneself to also carefully consider a proper EEOS (Electrical Equipment Organizational System) or similar software.  There should be careful considerations of safety, conditions of equipment and the environment of said equipment.  As long as a strong foundation is build in the beginning, maintaining compliance will be much simpler and lead to better equipment management, outages and minimize the risk to the electrical maintenance personnel.

References

Stallcup’s Electrical Equipment Maintenance, 2018

NFPA 70B Electrical Maintenance Standards, Chapter 9 – Maintenance Intervals, 2023

ISO 31000, Risk Management – Principles and Guidelines, 2022

Annex F of NFPA 70E

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