Assessing replacement of electrical systems
Replacement of electrical systems is a study of economics and risk. Factors including age, safety, reliability, efficiency, and energy costs must be weighed in conjunction with replacement costs and liability risk to formulate and prioritize upgrade plans. A comprehensive cost-benefit analysis study for each electrical subsystem will allow facilities to plan short-term and long-term expenditures for maintenance and upgrade programs for prudent facility reinvestments, replacements, and growth.
- Illustrate the reasons that electrical engineers should conduct studies of electrical and power systems
- Summarize the types of electrical equipment that should be reviewed for replacement
- Analyze the codes and standards that dictate equipment design.
Facilities’ needs and their aging electrical systems change over time. Aging systems and newer technologies constantly challenge facilities managers in repair and replacement considerations. Systems retro-commissioning, assessments, and master planning analyses are all methods to understand whether electrical systems are safe and operating correctly and efficiently to meet performance goals.
Such studies can indicate if systems can put the facility at risk, how systems are currently performing, can provide measurements, and set priorities for improvements. Balance scope, schedule, and cost of these improvements so business budgets, operations, and schedules can then be prudently planned.
Why and when to analyze
The performance of systems, operation, and users tend to drive the economy of the business world. Goals drive performance metrics that, in turn, will drive programs and action as well as associated operating costs. Performance measures must be communicated to deliver expected results and drive the systems analyses. Typical goals of an electrical system analysis may include age and condition, safety and security, code compliance, capacity for growth, reliability and redundancy, energy efficiency, physical distribution, ease of operation, and maintainability.
Facilities and their systems should be evaluated every 10 years to realign with current business strategies. Planning may include spaces to be repurposed, technology changes, and systems that operate less efficiently as they age. As most electrical distribution equipment have a 20-year expected life, 10-year status investigation increments are adequate to cover new, mid-life, and end-of-life evaluation.
It also becomes time to analyze electrical systems when facility growth or renovation is anticipated, associated affecting systems are due for replacement, failures begin to regularly occur, operating or energy costs unexpectedly rise, or when third-party funding opportunities (e.g., energy grants, utility incentives) become available for a known upgrade or need.
What to analyze
Professional design, service, and contracting organizations offer varying methods and analysis tools. Firms with the wide or narrow focus of systems expertise specific to the needs of the facility assessment should be chosen. For instance, infrared electrical inspections quickly find hot spots caused by defects in connections and components. Specific overall assessment personnel should have a minimum of 15 to 20 years of expertise and are knowledgeable in long-term building systems care and applicable codes and standards. They must be knowledgeable in the nuances of older and newer technologies, retrofits, and lifecycle costs and be sensitive to the overall goals of the facility such that they can help to prioritize any needs of these systems. The facility’s own staff will tend to focus on what they are used to or what is in need of repair; therefore, they may lack the flexibility for change or global insight necessary in both short- and long-term cost-benefit solutions.
Many factors come into play when analyzing and prioritizing electrical equipment needs. Life safety hazards should be prioritized first to maximize human safety and minimize potential high legal and operational risks.
Electrical equipment deterioration may be due to daily temperature cycles, collection of dust, condensation, mechanical wear of circuit breaker contacts and contactors, weakening of operating springs, deterioration of insulating materials, and rusting enclosures. The industry life expectancy for commercial-grade electrical systems in buildings is generally 20 to 30 years, if maintained properly, outlined as follows:
Electrical equipment ages at different rates based upon the quality of equipment, maintenance, and environment. Enhanced preventive maintenance care, regular duty-cycle operation, and lower operating temperatures will extend the equipment’s useful life. Aging electrical components are potential hazards, as their failure is unpredictable and can cause arcing, fires, failures, and associated human-safety issues.
Low-voltage cabling materials that should be considered for replacement include pre-1960s conductors having asbestos insulation and pre-2000 aluminum compression lugs, which may be subject to arcing conditions. Aging equipment will eventually reach a condition in which its reliability becomes questionable.
Code and safety issues
Fault-current rating: Electrical equipment fault-current ratings are based on the highest electrical current the equipment can withstand in the event of a short-circuit condition. Calculating the fault-current rating entails identifying the available fault current, which originates from the utility, generators, and running motors. If the available fault current exceeds the equipment’s rating and a fault occurs in the system, then a catastrophic failure of the equipment could occur. A system can become unsafe due to remodeling and expansion projects that add additional fault current without updating or maintaining an accurate fault current study.
Selective coordination: Electrical system coordination is required by NFPA 70: National Electrical Code, Articles 517, 700, and 701, and NFPA 99: Health Care Facilities Code. It assures that each overcurrent device trips in sequential order, isolates the problem condition, and does not cause unnecessary disruption of power upstream. Many times, interpretation prudently enforces the same coordination on normal power systems and is considered good practice.
Ground-fault protection is handled similarly in larger health care facilities. These facilities require two levels of protection, the main service overcurrent protective device (OCPD) and the second level OCPD to assure a feeder breaker opens on a fault condition prior to tripping the main circuit breaker. Large health care emergency systems also are required to have ground-fault alarm indication, not tripping, as the system is a facility’s last opportunity to maintain power in an emergency.
Arc flash hazard: Arc flash ratings are based on the equipment’s ability under a fault condition to cause an explosion, or arc fault. The rating defines the equipment’s ability to deliver energy and correlates to the personal protective equipment (PPE) gear an electrician is required to wear to be safe when working on or around energized equipment. Safety parameters are defined in NFPA 70E: Standard for Electrical Safety in the Workplace.
The incident energy level is directly proportional to the available fault current level available at the equipment and the time it takes to clear a fault condition. Older equipment may take more time to clear, which makes for increased concern.
Although the arc-flash-hazard level of electrical equipment is not a specific code requirement, except to OSHA, it is often a determining factor in the decision to replace existing equipment. The electrical system of many occupancies must remain energized during maintenance procedures, and the lower the arc flash hazard of the equipment, the safer the personnel who are working on that equipment.
Seismic provisions: Essential electrical equipment bracing is now required in seismic zones for essential buildings, such as health care facilities. Essential buildings, themselves, are also now similarly required to be structurally seismically braced.
Lightning protection: A lightning-protection risk analyses should be performed per NFPA 780: Standard for the Installation of Lightning Protection Systems to evaluate the need for building protection. Older systems should be reviewed for condition and connectivity conformance with this standard. Protection of buildings’ electronic equipment and associated insurance carrier requirements and rates also should be integral to the evaluation.
Grounding and bonding: Bonding of metallic components and earth grounding for electrical systems is commonly misunderstood, and human safety and equipment protection may be compromised if not properly accomplished. Independent-source grounding methods at services, transformers and generator systems, exposed equipment grounding, corrosion of grounding electrodes, and patient-care grounding systems should be properly evaluated.
Harmonics ratings: Overheating of electrical equipment may be caused by nonlinear electronic sources. Proper harmonic equipment ratings or harmonic-mitigation techniques should be reviewed.
Testing reports: Equipment testing reports per the InterNational Electrical Testing Association‘s acceptance testing specifications are valuable for outlining equipment conditions, duty cycles, and loading. Frequency and time-of-day parameters of the testing provide additional insights on the validity of the data.
Prolonged utility-loss impacts: The likelihood and impact of a prolonged outage to the safety and operation should be considered in an assessment. Standby systems, if available, should be reviewed as to their ratings and capabilities to sustain life safety and business-critical functions. A utility outage report should be reviewed for the frequency of their outages.
Component weak links: Critical and aging electrical components that are key to system operation must be analyzed for reliability. Bypass or backup opportunities should be considered. Critical equipment may consider N+1 redundancies as a minimum. Ratings of older equipment should be reviewed as to their adequacy given system adjustments or renovations over the years of operation and facility updates.
Physical locations: Critical electrical equipment should not be located where susceptible to floods, moisture, other natural disasters, or impediments caused by normal operations. Backup systems equipment should not be co-located so an incident could potentially take out both.
Power quality: Power sources, distribution systems, and loads should be analyzed as to voltage drop, voltage regulation, surges, spikes, brownouts, and harmonics. Utility-voltage regulation and the need for service tap changers or power conditioning should be reviewed. Sensitive electronic equipment should be reviewed for power quality needs including uninterruptible power supply (UPS) systems’ abilities to ride through or provide proper power conditioning. Harmonic impacts from nonlinear loads may require harmonic mitigation or more robust distribution systems to accommodate their inherent system heating effects. Elevator regeneration into the electrical distribution system may also cause power-quality issues.
Capacity: The ability of the electrical systems to handle the existing or potential increased load, perhaps for building expansion, should be reviewed. Normal power, generator backup, and UPS systems should be studied. Generator systems should be evaluated for block-load capacity and under loading conditions that cause diesel generator wet stack, which can reduce generator performance and life.
Ratings: Existing electrical equipment backfed from new higher-capacity sources may require additional costs for installation of current-limiting protective devices, higher-impedance transformers, or high-resistance grounding systems to minimize energy let-through due to the older equipment’s lower fault-current ratings.
Equipment expansion capability: Though the ratings of the existing equipment are capable of handling additional loading, physical limitations may prevent the system’s ability to service new loads.
Physical distribution: Voltage-drop limitations may impede system expansion and require the additional cost of higher-voltage distribution equipment.
Code compliance: Older electrical systems were installed under less stringent code requirements. Touching these systems for growth or renovation may require updating to meet the current authority having jurisdiction’s (AHJ) code requirements, such as generator distribution branch separations, protective device coordination updates, clearances around electrical equipment, disconnects, etc.
Efficiency: High-efficiency LED lighting, motors, and transformers should be evaluated on a cost-benefit basis for replacement. Similar analyses should be performed for the installation of power factor correction capacitors on older systems to reduce operation and utility cost.
Controls: The best way to save energy is to turn electrical equipment off. Evaluation of lighting, generator, and HVAC systems controls to reduce energy usage should be considered. New energy guidelines and codes also focus on receptacle and phantom loads that are left on when not required (e.g., computers, copiers, water coolers, etc.).
Fuel sources: Generator systems’ fuel sources should be evaluated to minimize energy costs. Capital-cost replacement of generators may be overcome by reduced long-term fuel costs. Electrical power management (digital monitoring and control) systems may be used to minimize operating costs by switching to the lowest-cost alternative automatically. Optimizing mixes of demand-response and onsite supply or renewable generation in response to electric-utility company contract/rate obligations can be achieved while minimizing fuel costs and providing proactive measurement and verification of system efficiencies.
Ease of operation and maintenance
An assessment and subsequent repairs of electrical distribution equipment should assure a reliable infrastructure that is less costly to maintain, easier to operate, and offers enhanced safety to personnel. A well-structured power-monitoring system provides real-time values, trending, diagnostic, and alarms to proactively manage the system. Barcoding systems labeling also have become useful by providing quick field access to associated equipment maintenance and operating data.
As systems age, equipment becomes obsolete, workarounds and multiple manufacturers come into play, maintenance data and rating nameplates are lost, electrical drawings are lost or not updated, equipment IDs become inconsistent or missing, and design intent becomes unknown. Reliability determination, available capacities, planning for phased updates, and safety conditions, therefore, become hard to analyze. Electrician interviews, testing, and detailed surveys may need to be performed to ensure existing conditions are known, documented, and properly evaluated.
How to analyze and prioritize
Building facility groups struggle to prioritize their maintenance and upgrade budgets. They are constantly challenged to minimize expenditures and equipment downtime while maximizing human safety and system reliability. Once the conditions of the distribution system are documented, the prioritization and phasing of potential corrective measures must be systematically evaluated, categorized, and sequenced, and the costs estimated in conjunction with the overall facility goals. The electrical systems should be categorized for each facility building or area as follows:
- Service equipment
- Medium-voltage distribution
- Low-voltage distribution Generator power and distribution
- Diagnostics, metering, and monitoring Lighting and lighting controls
- Branch wiring and wiring devices
- Grounding, bonding, and lightning protection.
Each system should be scored with a good, satisfactory, or marginal rating (or numerically weighed) in each of the following system issues to come up with an overall rating:
- Remaining life Capacity
- Physical distribution
- Energy efficiency
- Ease of operation
- Expansion capability.
This approach will provide areas of focus for systems in need for each designated building area as well as provide a snapshot of potential risks. The risks will vary for each facility situation; however, they can generally be prioritized by:
Life safety/code compliance: Assessing the replacement of electrical systems must start with the identification of life safety and code-compliance issues, with associated potential failure points that affect risk and facility operation as first priority. Compliance with local code, as indicated by the AHJ, is required.
Litigation exposure: Electrical upgrades must take into account legal and business consequences that may far outweigh the financial cost of the upgrades, themselves. Any cost-benefit prioritization must start here.
Facility-operation vulnerability/occurrence likelihood: The desired electrical system’s reliability and flexibility to cost-effectively react and adapt may have been unknowingly sacrificed due to the day-to-day changes associated with the operational needs of the facility. Reliability and probability calculations may be required for critical equipment subjected to high operational stress along with an evaluation of the facility’s preparedness in dealing with unscheduled events.
Life expectancy need: Defining the life expectancy of electrical equipment will indicate how ongoing facility maintenance, growth, and master planning will affect the associated electrical system’s life extension or replacement needs.
Potential updates should be outlined to a level so they can be cost-estimated to obtain a realistic budgetary number for each need to weigh its associated update cost-benefit and priority. Use of in-house resources versus construction contractors should be included in the evaluation. There is no straight-line approach in the assessment of electrical systems, as each facility’s conditions resources and priorities are different; therefore, the facilities administration, engineering, and maintenance staff should be included in the ranking process and evaluation. Their input on concepts, design, installation, commissioning, operation, and maintenance of facility systems allows for good documentation and maintenance with sound assessment and investment approaches.
Insightful planning, management, and maintenance will create a strategic road map for safe and reliable electrical system management. Achieving a proper assessment must start with a clear understanding of the existing system and potential facility enhancements. Only then can identification of risks, key weaknesses and limitations, what financing is available, and what balance can be achieved can be weighed in a cost-benefit financial approach to prioritization and scheduling of required improvements.
The replacement of electrical systems has become a study of economics and risk. Factors such as age, safety, reliability, efficiency, and energy costs must be weighed in conjunction with replacement costs and liability risk to formulate and prioritize upgrade plans. A comprehensive cost-benefit analysis study for each electrical subsystem will allow facilities to plan short- and long-term expenditures for maintenance and upgrade programs for prudent facility reinvestments, replacements, and growth. This is essential for all corporate facilities and institutions in their financial and business planning.
Theodore Fowler is an electrical engineering principal at CannonDesign. He leads the firm-wide engineering practice strategies team, which guides how CannonDesign works collaboratively to provide integrated, high-quality solutions to meet design challenges.