Electrical demand changes as production shifts, new lines start up, or seasons change. Nameplate math and old drawings cannot show how your system behaves in real life. A load study gives you measured data on how power flows through services, transformers, and feeders. With that information, you can prevent overloads, reduce nuisance trips, and plan safe capacity growth with confidence.
A load study records power and current over time at key points in your electrical system. Typical values include kilowatts (kW), kilovolt-amperes (kVA), current, voltage, and power factor (PF). Many studies also record harmonics and brief voltage dips.
- A clear picture of peaks and patterns by shift and season
- A list of circuits or transformers at risk of overload
- Practical fixes to balance loads, adjust settings, or schedule large equipment at better times
- A simple capacity map that shows where you have headroom
- Real power (kW) and apparent power (kVA)
- Current and voltage on each phase
- Power factor to spot waste and heating
- Short intervals, for example 1 to 15 minutes
- Enough time to cover busy shifts, weekends, and at least one weather change if loads are seasonal
- Harmonics from drives and IT gear can heat neutrals and transformers
- Voltage dips can cause motors or controls to trip at the worst time
Measurement Point | What you Learn | Why it Matters |
Service main | Site peak and coincident peaks | Confirms safe headroom and demand charges |
Transformer secondary | Loading percent, phase balance, neutral current | Protects insulation life and reduces overheating risk |
Critical feeder | Local peaks and motor start dips | Prevents nuisance trips and process interruptions |
Panel with VFDs or IT loads | Harmonics and neutral loading | Flags hidden heating and early failure risks |
Find feeders and transformers trending toward overload so you can correct issues before heat damage or unexpected outages.
Rebalance phases and panels to cut extra heating and reduce neutral current in harmonic-heavy areas.
Identify feeders that need soft starts, staggered starts, or larger conductors to avoid voltage dips that shut down nearby equipment.
Use measured demand and inrush to set protective devices so they protect equipment and avoid needless trips.
A desktop load study uses your one-line diagram, panel schedules, nameplates, and utility bills to estimate demand. It is great for early planning, but it cannot see real coincident peaks, motor starting dips, or harmonics. Use the desktop pass to plan meter placements, then validate with measured data.
Read the overview: How to Do a Load Study (Desktop Calculation)
- Transformers and feeders run within their ratings with a safety margin
- Continuous loads follow the 125 percent design intent from the National Electrical Code (NEC)
- Phase balance is improved and neutral current stays within limits
- Voltage drop at critical loads stays within target values
- Protective device settings match measured demand and inrush, with as-found and as-left recorded
Update the one-line diagram and panel schedules after any changes so teams can isolate safely during future work.
If settings or system layout change, re-run short-circuit, coordination, and arc-flash studies, then update labels.
Follow Electrically Safe Work Condition (ESWC) and Lockout or Tagout (LOTO) rules from NFPA 70E when installing meters or making corrections. Store logs, settings, and photos in your Computerized Maintenance Management System (CMMS).
If it is not on the one-line and in the CMMS, it did not happen. Capture the record before you close the job.
- NFPA 70B (2023) supports using measured data inside your Electrical Maintenance Program (EMP) to set priorities and intervals
- NFPA 70E guides safe work planning, ESWC, and LOTO during installs and corrections
- OSHA 1910.303 requires equipment to operate within ratings. OSHA 1910.333 and 1910.147 require de-energized work when feasible and control of hazardous energy
- NEC Articles 215, 220, 230 help validate feeder and service sizing, continuous load at 125 percent, and acceptable voltage drop
- Fewer unplanned outages and nuisance trips
- Mean Time Between Failures (MTBF) trending up
- Peak and coincident demand by shift and season
- Phase and neutral balance within targets
- Documentation and label currency during audits
Get an Electrical Load Study Readiness Assessment
Make capacity and protection decisions with real data. Avoid overloads, protect equipment life, and plan upgrades with confidence.
References
- National Fire Protection Association. (2023). NFPA 70B: Standard for Electrical Equipment Maintenance (2023 ed.). NFPA.
- National Fire Protection Association. (2024). NFPA 70E: Standard for Electrical Safety in the Workplace (latest ed.). NFPA.
- Occupational Safety and Health Administration. (n.d.). General requirements, 29 CFR 1910.303; The control of hazardous energy, 29 CFR 1910.147; Selection and use of work practices, 29 CFR 1910.333. U.S. Department of Labor.
- National Fire Protection Association. (2023). NFPA 70: National Electrical Code (NEC). Selected Articles 215, 220, 230. NFPA.
- IEEE. (2010). IEEE 3007.2-2010: Recommended Practice for the Maintenance of Industrial and Commercial Power Systems. IEEE.