Field tools
Electrical calculators and references
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Electrical Calculations
Solve electrical quantities and check circuit performance with field-focused calculations.
Control Transformer Load CalculatorCompare continuous and startup control VA with transformer capacity.Ohm’s Law and Power CalculatorCalculate electrical values and AC power.AC Power and Current CalculatorCalculate AC current from real power, voltage, phase, and power factor.Capacitor Bank Capacitance CalculatorEstimate power-factor correction kVAR and capacitance.Fundamental Neutral Current CalculatorPhasor-sum fundamental phase currents for supported split-phase and three-phase wye systems.Harmonic Distortion CalculatorCalculate THD and total RMS from fundamental and harmonic measurements.Transformer Current and Overcurrent Protection CalculatorCalculate winding current and review primary/secondary device limits.Transformer kVA Sizing CalculatorAdd user-selected headroom to an entered load demand and compare a selected transformer rating.Buck-Boost Transformer CalculatorEstimate correction voltage, winding current, and transformed VA for buck-boost applications.Transformer Turns Ratio CalculatorCalculate ideal winding voltage, turns, and current relationships from winding values.Transformer Tap Voltage CalculatorEstimate secondary voltage from actual supply voltage and a selected primary nameplate tap.Transformer Voltage Regulation CalculatorCalculate measured voltage regulation or estimate it from resistance, reactance, and load power factor.Transformer Efficiency and Loss CalculatorEstimate load-dependent losses, efficiency, annual loss energy, and energy cost from entered test data.Open-Delta Transformer Capacity CalculatorEstimate balanced-bank capacity for two equal transformer units in an open-delta arrangement.Electrical Unit ConverterConvert electrical quantities and conductor area.Series and Parallel Resistance CalculatorCalculate equivalent resistance, source current, and branch values for simple resistive circuits.Voltage Divider CalculatorEstimate divider output, including the effect of an optional resistive load.Current Divider CalculatorCalculate equivalent resistance and branch currents for parallel resistive branches.Resistive Load Bank CalculatorCalculate element voltage, line current, and total power for single-phase or balanced three-phase resistive load banks.Resistive Load Voltage Change CalculatorCompare current and power when a fixed-resistance load operates at a different voltage.Power Factor Correction CalculatorEstimate the reactive-power compensation needed to raise a lagging displacement power factor.Three-Phase Voltage Unbalance CalculatorCalculate maximum deviation from average using three measured line-to-line voltages.Three-Phase Current Imbalance CalculatorCalculate average phase current and maximum percent deviation across three readings.AC Impedance and Reactance CalculatorEstimate reactance, impedance magnitude, and phase angle for a simple series RLC circuit.RLC Resonant Frequency CalculatorCalculate ideal LC resonant frequency from inductance and capacitance.Current Transformer Ratio CalculatorConvert measured CT secondary current to estimated primary current using entered nameplate ratings.Instrument Transformer Meter Multiplier CalculatorCombine CT and PT ratios and adjust a register value for an existing meter multiplier.4–20 mA Signal Scaling CalculatorConvert loop current to an engineering value or calculate current from a configured range.Current Loop Load Resistance CalculatorEstimate the remaining allowable loop resistance from supply voltage and entered device voltage drops.
Conductors & Raceway
Check conductor, grounding, raceway, box, and wiring installation tasks.
Conductor Ampacity CalculatorApply ambient and conductor-count corrections.Bonding Jumper Sizing ReferenceLook up main, system, and supply-side bonding jumper size.Box Fill CalculatorEstimate box volume from conductors and devices.Branch Circuit Conductor and Breaker CheckCompare general-load requirements with a conductor and breaker.Cable Pull Tension and Sidewall Pressure CalculatorEstimate tension and bend pressure along a cable-pull route.Cable Tray Fill and Ampacity WorksheetCompare cable area and apply an entered ampacity factor.Cable Minimum Bend Radius CalculatorCalculate pulling and installed bend-radius limits from cable outside diameter and manufacturer multipliers.Cable Reel Capacity CalculatorEstimate cable length from reel flange, barrel, width, cable diameter, and packing factor.Copper vs Aluminum Wire Cost CalculatorCompare user-entered material and termination costs for two conductor alternatives.Conduit Bend CalculatorLay out stub-ups, offsets, and saddle bends.Conduit Offset CalculatorCalculate offset bend marks, spacing, and shrink from obstacle clearance and bender data.Three-Point Saddle CalculatorLay out center and return marks around a conduit obstruction.Four-Point Saddle CalculatorLay out four marks using the selected bender table values and reference convention.Stub-Up Bend CalculatorCalculate a 90-degree stub-up mark from desired height and bender take-up.Rolling Offset CalculatorResolve horizontal and vertical offsets into true offset, rotation, shrink, and marks.Back-to-Back Conduit Bend CalculatorCalculate opposite-end stub marks and remaining spacing from conduit length and take-up.Kick Bend CalculatorCalculate horizontal run and sloped conduit length from required rise and kick angle.Parallel Conduit Offset CalculatorCalculate staggered bend marks for multiple parallel conduit offset runs.Segmented Conduit Bend CalculatorCalculate segment angle, chord, and arc length for a large-radius segmented bend.Conduit Fill CalculatorEstimate raceway fill from conductor count and size.Dwelling Receptacle and Circuit Quick ReferenceReview outlet placement and required branch circuits by room.Equipment Grounding Conductor CalculatorLook up minimum EGC size by overcurrent-device rating.Feeder Conductor Sizing and Voltage Drop CalculatorFind the smallest listed feeder conductor meeting ampacity and voltage-drop targets.Grounding Electrode Conductor Size CalculatorLook up a grounding electrode conductor from service-conductor size.NM Cable Support and Protection ReferenceCheck cable support, framing protection, and floor passages.Pull Box and Junction Box Sizing CalculatorEstimate box dimensions for straight, angle, U, and splice pulls.Raceway Fill and Ampacity CalculatorCheck mixed-conductor raceway fill and ampacity adjustments.Receptacle and Plug Identification ReferenceLook up common NEMA markings, ratings, and grounding contacts.Voltage Drop and Wire Size CalculatorEstimate circuit voltage loss and compare listed conductor sizes.Wire Resistance CalculatorEstimate one-conductor and current-path resistance from material, conductor size, length, and temperature.Wire Power Loss CalculatorEstimate I-squared-R conductor losses and annual energy cost for single-phase or balanced three-phase circuits.Parallel Conductor Sizing CalculatorEstimate per-set current and voltage drop for identical parallel conductors.Feeder and Branch Circuit Voltage Drop CalculatorSum estimated voltage drop through feeder and branch-circuit segments using separate load and conductor inputs.
Loads & Services
Plan service loads, feeders, jobsite power, and connected energy systems.
Battery Runtime CalculatorEstimate runtime from battery energy and a steady load.EV Charging Energy Cost CalculatorEstimate grid energy, session cost, annual charging cost, and cost per mile from user inputs.Lighting Retrofit Savings CalculatorEstimate energy and maintenance savings, net project cost, and simple payback for a lighting replacement.Commercial Material and Labor EstimateBuild a rough estimate from user-entered quantities and prices.Commercial Feeder and Service Load CalculatorEstimate non-dwelling load and review a separate conductor-sizing basis.Multifamily Dwelling Load CalculatorEstimate connected and diversified load for repeated dwelling units.Household Range Demand CalculatorEstimate cooking appliance demand from count and nameplate rating.Household Dryer Demand CalculatorEstimate clothes dryer demand from count and nameplate rating.Fixed Appliance Demand CalculatorEstimate demand for qualifying fixed appliances.Heating and Cooling Noncoincident Load CalculatorSelect the larger heating or cooling load when systems cannot operate together.Commercial Kitchen Equipment Demand CalculatorEstimate diversified demand from connected commercial kitchen equipment.Commercial Receptacle Load CalculatorEstimate connected and demanded load from commercial receptacle yokes.Commercial Lighting Load CalculatorCalculate connected and continuous sizing load from area and unit load.Panel Phase Load Balance CalculatorCompare phase loads and quantify maximum imbalance from average.Continuous Load Circuit Capacity CalculatorApply continuous-load sizing treatment and calculate required current.EV Charging Load Management CalculatorCompare EV charging demand with available service capacity.PV Array and Inverter Ratio CalculatorCalculate DC array to inverter size ratio.PV Interconnection Busbar CalculatorCompare main and PV breaker contributions with a bus rating.Battery Storage Capacity CalculatorEstimate required storage energy for load, duration, usable capacity, and efficiency.Temporary Power Load CalculatorSum temporary loads and calculate source current.Conductor and Raceway Quantity CalculatorEstimate conductor counts, total length, and average loading across raceways.Generator Fuel Runtime CalculatorEstimate runtime from tank volume and fuel consumption.UPS Capacity CalculatorEstimate UPS kVA from load, power factor, and headroom.Dwelling Load CalculatorCalculate one-family service load using standard or optional methods.EV Charging Time CalculatorEstimate battery charging time from charge level and EVSE output.EVSE Circuit and Service Load PlannerCheck one charger circuit and its added dwelling service load.Generator Load and Motor Start EstimatorCompare steady and motor-start loads with generator ratings.Lighting Fixture Count and Spacing EstimatorEstimate fixture count and even-row layout spacing.PV String and DC Wiring CalculatorEstimate cold string voltage, inverter limits, and DC wire drop.Residential Material Takeoff EstimatorEstimate device, box, cable, raceway, and conductor quantities.Existing Service Capacity CalculatorCheck proposed loads against an existing dwelling service.Temporary Power Cord Screening ToolCheck cord current and voltage drop from jobsite inputs.
Equipment & Systems
Work with motors, communications, protection, and installed electrical equipment.
Arc-Flash Label Data HelperCheck that study-supplied label fields and review records are present.Available Fault Current and SCCR ScreenEstimate fault current at transformer terminals and equipment.Multiple Motor Feeder CalculatorEstimate feeder current from multiple motor currents and largest-motor adder.Motor Speed and Slip CalculatorCalculate synchronous speed and induction motor slip.Motor Starting Current CalculatorEstimate locked-rotor current from full-load current and multiplier.VFD Motor Speed CalculatorEstimate motor speed from drive frequency and slip.Protective Device Time-Current Curve Comparison CalculatorCompare interpolated clearing times from two supplied protective-device curves.Emergency Lighting Runtime ScreenCheck emergency lighting energy against a required duration.Emergency Lighting Illumination CalculatorEstimate direct illuminance at one point from fixture photometric data and geometry.Industrial DC Power Supply Sizing CalculatorCompare continuous and transient DC loads against manufacturer supply ratings.Redundant DC Power Supply Capacity CalculatorCompare normal and single-module-failure capacity with DC system load.Control Panel Heat Load CalculatorSum component losses and external heat gain for an enclosure heat-load estimate.Enclosure Ventilation Airflow CalculatorEstimate ideal ventilation airflow from enclosure heat load and allowable temperature rise.Enclosure Cooling Capacity CalculatorEstimate enclosure active cooling demand from heat load, dimensions, ambient, and target temperature.Welding Circuit Sizing CalculatorScreen welder conductor and protective-device values using entered nameplate and rule factors.Industrial Enclosure Environment ReferenceFilter NEMA type descriptions by location and exposure.Energy Control Checklist BuilderRecord energy sources and isolation points against a written procedure.Fire Alarm Battery Load WorksheetCalculate standby and alarm amp-hour demand from project inputs.GFCI and AFCI Requirement FinderCheck selected circuit-protection requirements by location and circuit details.Low-Voltage Cable Voltage Drop EstimatorEstimate two-wire DC cable drop from manufacturer resistance data.Motor Full-Load Current and Circuit Protection ReferenceLook up motor table FLC, branch-conductor ampacity, and general protection limits.Motor Overload Protection Setting ReferenceCalculate normal and conditional overload trip-current limits.Motor Energy Cost CalculatorEstimate electrical input power, annual energy, and operating cost from shaft load and efficiency.Motor Efficiency Upgrade Payback CalculatorCompare energy costs at equal shaft duty and estimate simple payback for a replacement motor.Pump and Fan Speed Energy CalculatorEstimate relative flow, head, and shaft power at a changed speed using ideal affinity laws.Motor Voltage Drop EstimatorEstimate running and starting voltage drop from motor and conductor data.Standard Overcurrent Device Rating CalculatorFind the next standard fuse or breaker ampere rating.PoE Power Budget EstimatorCompare device demand with switch and port power limits.Notification Appliance Circuit Voltage Drop CalculatorEstimate segment-by-segment DC voltage drop and appliance terminal voltage.Access Control Power Supply CalculatorEstimate controller, lock, and accessory current for standby and simultaneous activation.Security System Backup Battery CalculatorEstimate backup capacity from security system standby and alarm loads and durations.Distributed Speaker Load CalculatorSum speaker transformer taps and compare with amplifier output capacity and headroom.Equipment SCCR Comparison CalculatorCompare study-provided available fault current with assembly SCCR and voltage ratings.Ground-Fault Loop Current EstimatorEstimate grounded fault current from source voltage and complete loop impedance.Three-Phase Motor Power and Torque CalculatorEstimate motor input power, shaft horsepower, and torque.VFD and Motor Compatibility WorksheetScreen rated current and track manufacturer review items.
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