Sheet E-001
Engineering Tools
Free calculators and viewers our engineers use on real projects. Each one runs in your browser and sends nothing to us. Bookmark the ones you use.
Bus ACables and raceways
MV Cable Ampacity CalculatorMedium-voltage cables to 35 kV, buried or in air, with a conduit size and type for each duct. Steady-state and emergency ratings in amperes and MVA, several cases per project, and a heat map of the duct bank.IEC 60287, Neher-McGrathLV Cable Ampacity CalculatorCables from 600 V to 2 kV in duct banks, direct buried, in conduit in air or in free air, from the NEC tables or by Neher-McGrath.NEC 2023, Neher-McGrathCable Pulling CalculatorPulling tension and sidewall bearing pressure along a conduit route, in both directions, for cable to 35 kV.IEEE 1185, Southwire guideConduit Fill CalculatorFill for building wire, medium-voltage cable to 35 kV, Ethernet and fiber, with jam ratio and clearance checks.NEC Chapter 9Cable Testing LabHow power cable field tests work: insulation resistance, PI and DAR, sheath, VLF, tan delta, partial discharge and TDR. Each test has a connection diagram, a live result to explore with sliders, and what it shows and misses.IEEE 400 series (concepts), IEC 60287 capacitance
Bus BShort circuit and arc flash
Fault Current CalculatorSingle- and three-phase bolted fault current from the utility source to the end of the cable.Ohmic methodShort Circuit and Arc FlashDraw a low-voltage one-line to 480 V ac or 1500 V dc, or build it from an ETAP project, then get fault currents, device coordination and arc flash labels.IEEE 1584, NFPA 70ESequence Fault VisualizerHow a fault's currents split into positive, negative and zero sequence across a transformer, including ground faults on ungrounded systems through cable capacitance and on 12.47 kV multigrounded, unigrounded and hybrid lines, with voltage rise and arrester checks.Symmetrical components, IEEE C62.92.1, C62.22
Bus CBuilding circuits and equipment
Circuit CalculatorBranch circuits and feeders of 1000 V and less: protection, conductors, grounding, raceways and voltage drop.NEC 2023Transformer CalculatorProtection, conductors, grounding and raceways for transformers of 1000 V and less.NEC 2023Motor CalculatorBranch circuits for motors of 1000 V and less: protection, conductors, grounding, raceway and control.NEC 2023Panel Schedule CalculatorPanelboard and switchboard schedules, branch-circuit sizing and load calculations.NEC 2023
Bus DOverhead distribution
Bus EPower system models
SKM ViewerOpen an SKM PowerTools project in your browser: the one-line diagram, load flow, short circuit and cable ampacity, with each cable's construction, its duct bank and conduit fill, and a printable report. Nothing is uploaded.SKM PowerTools projects, IEC 60287ETAP ViewerOpen an ETAP project in your browser: the one-line, load flow, short circuit and arc flash, with clearing times from SEL relays. Nothing is uploaded.ETAP projects, IEEE 1584PSLF ViewerOpen GE PSLF EPC, DYD and DRW files: one-line, power flow, short circuit, dynamics and WECC data checks. Nothing is uploaded.GE PSLF, WECC checks
Bus FDrawings
Bus GGrounding
Bus HEngineering economics
Loan Amortization CalculatorLoan payments and the full payoff schedule, with extra payments, interest-only and balloon terms, and a side-by-side refinance comparison.Time value of moneyInvestment Growth CalculatorSavings growth with regular contributions, or the contribution, return or time needed to reach a goal, with inflation and interest factors.Time value of moneyProject Economics CalculatorNet present value, IRR, payback and levelized cost of energy for capital projects such as solar, battery storage and efficiency upgrades.NPV, IRR, LCOE
Bus IProtection and relaying
Protection LabHow protective relays measure, decide and trip: 31 ANSI device functions, a feeder coordination lab and a transformer differential and inrush lab, with the reason behind every trip and every restraint.IEEE C37.2, C37.112, C37.91Transformer Fusing LabPrimary fusing for pad-mounted transformers: internal Bay-O-Net and backup current-limiting fuses, external S&C SM-4 and SM-5 power fuses, or both, coordinated from the manufacturer's curves, with transformer protection for every fault type, loading requirements and secondary arc flash, and the status and reason behind every result.IEEE C57.12.00, IEEE 1584
Bus JDrones and mapping
Aerial3D WaypointsPlan waypoint missions for photogrammetry and 3D models with the DJI Mini 5 Pro: nadir grids, oblique cross-grids, orbits, facade scans and free waypoint paths, exported as DJI Fly KMZ files.DJI WPML (KMZ)Aerial3D ModelTurn drone photos and ground-level 360 photos and video (including Insta360 .insp and .insv originals) from one or more folders into an orthophoto, elevation models, a point cloud and a textured 3D mesh, with or without GPS, and add new photos to a finished model. The page is the front end; the processing runs on your own PC with the free Aerial3D Engine.COLMAP and OpenMVS; GeoTIFF, LAZ, GLB and OBJView360Scroll through a folder of photos, 360 photos and 360 videos, including unstitched Insta360 .insp and .insv originals, stitched and leveled in your browser from the camera's own lens and tilt data. Mark up photos with clouds, callouts, text, arrows and crop, export a 360 JPG, and see where each photo was taken on a map linked to Google Maps and Google Earth. Nothing is uploaded.Insta360 X5; equirectangular JPG with GPano XMP