{"openapi":"3.1.0","info":{"title":"Electrical Calculators","version":"1.0.0","description":"Voltage drop, three-phase power, power factor correction, transformer sizing, wire resistance, energy cost, AC impedance and battery banks. One call, one computed answer, no accounts or API keys. Machine-payable over x402.","x-guidance":"Electrical Calculators: Voltage drop, three-phase power, power factor correction, transformer sizing, wire resistance, energy cost, AC impedance and battery banks. Use /voltage-drop for conductor drop, /three-phase-power for kW kVA kVAR and current, /power-factor-correction for capacitor kVAR, /transformer-sizing for kVA and full-load current, /wire-resistance for resistance and temperature correction, /energy-cost for kWh and tariff cost, /ohms-law-ac for series RLC impedance and resonance and /battery-bank for bank layout and runtime. Ampacity tables are not included: consult the electrical code. Each paid GET returns a computed verdict with the reasons, the source and what was NOT checked. A verdict of UNVERIFIED means a lookup failed: treat it as unknown. No account or key: pay per call in USDC over x402."},"servers":[{"url":"https://electrical-calc.x402tookit.com"}],"paths":{"/battery-bank":{"get":{"operationId":"battery_bank","summary":"Battery bank layout (series and parallel counts) and runtime from load, voltage, Ah, depth of discharge and efficiency.","description":"Battery bank layout (series and parallel counts) and runtime from load, voltage, Ah, depth of discharge and efficiency.","tags":["battery","runtime","bank","inverter"],"parameters":[{"name":"loadW","in":"query","required":true,"description":"Constant load in watts","schema":{"type":"number"}},{"name":"systemVoltageV","in":"query","required":true,"description":"Bank (DC system) voltage in volts, a whole multiple of batteryVoltageV","schema":{"type":"number"}},{"name":"batteryVoltageV","in":"query","required":true,"description":"Nominal voltage of one battery in volts","schema":{"type":"number"}},{"name":"batteryAh","in":"query","required":true,"description":"Capacity of one battery in amp-hours at its rating","schema":{"type":"number"}},{"name":"depthOfDischargePct","in":"query","required":false,"description":"Usable fraction of capacity in percent (default 50; 80 typical for lithium)","schema":{"type":"number"}},{"name":"efficiencyPct","in":"query","required":false,"description":"Inverter and wiring efficiency in percent (default 90; use 100 for a DC load)","schema":{"type":"number"}},{"name":"runtimeHours","in":"query","required":false,"description":"Target runtime in hours, to size the parallel strings","schema":{"type":"number"}},{"name":"parallelStrings","in":"query","required":false,"description":"Parallel strings you have, to get the runtime (default 1; ignored if runtimeHours is sent)","schema":{"type":"integer"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"batteriesInSeries":{"type":["null","number"]},"parallelStrings":{"type":["null","number"]},"totalBatteries":{"type":["null","number"]},"bankVoltageV":{"type":["null","number"]},"bankAh":{"type":["null","number"]},"bankWh":{"type":["null","number"]},"usableWh":{"type":["null","number"]},"usableWhPerString":{"type":["null","number"]},"runtimeHours":{"type":["null","number"]},"runtimeMinutes":{"type":["null","number"]},"batteryDrawCurrentA":{"type":["null","number"]},"loadWattHoursNeeded":{"type":["null","number"]},"dischargeRateC":{"type":["null","number"]},"depthOfDischargePct":{"type":["null","number"]},"efficiencyPct":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"BANK_SIZED","summary":"2 in series x 3 parallel = 6 batteries (7200 Wh); runs 500 W for about 6.48 hours at 50% depth of discharge.","reasons":["Series count = 24 V / 12 V = 2; bank amp-hours = 100 x 3 parallel = 300 Ah at 24 V.","Runtime = bank Wh x depth of discharge x efficiency / load.","…1 more"],"batteriesInSeries":2,"parallelStrings":3,"totalBatteries":6,"bankVoltageV":24,"bankAh":300,"bankWh":7200,"usableWh":3600,"usableWhPerString":1200,"runtimeHours":6.48,"runtimeMinutes":388.8,"batteryDrawCurrentA":23.14815,"loadWattHoursNeeded":2500,"dischargeRateC":0.07716,"depthOfDischargePct":50,"efficiencyPct":90,"degraded":false,"notChecked":["Peukert effect (high discharge rates reduce usable capacity)","temperature, ageing and charge-rate limits","…2 more"],"source":"computed locally (Wh = V x Ah; usable = Wh x DoD; runtime = usable x efficiency / load)","asOf":"2026-10-21T06:22:27.940Z","disclaimer":"Screening signal computed from the named public source. 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Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/battery-bank"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/battery-bank"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/battery-bank"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/battery-bank"}}]}}},"/energy-cost":{"get":{"operationId":"energy_cost","summary":"Energy use in kWh and its cost from a flat rate or tiered blocks, plus an optional demand charge and fixed fee.","description":"Energy use in kWh and its cost from a flat rate or tiered blocks, plus an optional demand charge and fixed fee.","tags":["energy","kwh","tariff","cost"],"parameters":[{"name":"powerKw","in":"query","required":true,"description":"Average running load in kilowatts (or send kwh to override)","schema":{"type":"number"}},{"name":"hoursPerDay","in":"query","required":false,"description":"Hours of use per day, 0 to 24 (default 24)","schema":{"type":"number"}},{"name":"days","in":"query","required":false,"description":"Number of days in the period (default 30)","schema":{"type":"number"}},{"name":"kwh","in":"query","required":false,"description":"Energy in kWh for the period; overrides powerKw x hours x days","schema":{"type":"number"}},{"name":"flatRatePerKwh","in":"query","required":false,"description":"Price per kWh in your currency (use this or tiers)","schema":{"type":"number"}},{"name":"tiers","in":"query","required":false,"description":"Blocks as size:rate pairs separated by semicolons, e.g. 100:0.10;200:0.15;inf:0.20 (kWh per block : price per kWh)","schema":{"type":"string"}},{"name":"peakKw","in":"query","required":false,"description":"Peak demand in kW for the demand charge (default powerKw)","schema":{"type":"number"}},{"name":"demandRatePerKw","in":"query","required":false,"description":"Demand charge per kW of peak per period (default 0)","schema":{"type":"number"}},{"name":"fixedCharge","in":"query","required":false,"description":"Fixed charge for the period in your currency (default 0)","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"kwh":{"type":["null","number"]},"averageKw":{"type":["null","number"]},"hoursPerDay":{"type":["null","number"]},"days":{"type":["null","number"]},"energyCost":{"type":["null","number"]},"demandCost":{"type":["null","number"]},"fixedCharge":{"type":["null","number"]},"totalCost":{"type":["null","number"]},"effectiveRatePerKwh":{"type":["null","number"]},"blocks":{"type":["array","null"],"items":{"type":"object","properties":{"kwh":{"type":["null","number"]},"ratePerKwh":{"type":["null","number"]},"cost":{"type":["null","number"]}}}},"unpricedKwh":{"type":["null","number"]},"peakKw":{"type":["null","number"]},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"COMPUTED","summary":"300 kWh over 30 day(s) costs 71 (energy 45, demand 16, fixed 10).","reasons":["kWh = kW x hours per day x days, unless kwh is given.","Each tier is a block of kWh priced at its rate; later blocks start where earlier ones end."],"kwh":300,"averageKw":2,"hoursPerDay":5,"days":30,"energyCost":45,"demandCost":16,"fixedCharge":10,"totalCost":71,"effectiveRatePerKwh":0.2366667,"blocks":[{"kwh":100,"ratePerKwh":0.1,"cost":10},{"kwh":100,"ratePerKwh":0.15,"cost":15}],"unpricedKwh":0,"peakKw":2,"degraded":false,"notChecked":["time-of-use rates, taxes, riders and fuel adjustments","power factor penalties and ratchet demand clauses","…1 more"],"source":"computed locally (kWh = kW x h; cost = sum of block kWh x rate + demand kW x rate + fixed)","asOf":"2026-10-21T06:22:28.206Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. 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Not financial, legal or investment advice; provided as is. 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Wye load: phase current = line current and phase voltage = line voltage / sqrt(3)."],"lineVoltageV":400,"lineCurrentA":100,"kw":55.42563,"kva":69.28203,"kvar":41.56922,"powerFactor":0.8,"phaseAngleDeg":36.8699,"deltaPhaseCurrentA":57.73503,"wyePhaseVoltageV":230.9401,"kwPerPhase":18.47521,"inputMode":"currentA","degraded":false,"notChecked":["unbalanced loads, harmonics or distortion power factor","leading versus lagging sign (Q is given as a magnitude)","…1 more"],"source":"computed locally (S = sqrt(3) V I; P = S cos phi; Q = S sin phi)","asOf":"2026-10-21T06:22:28.988Z","disclaimer":"Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting."}}}},"400":{"description":"A parameter was missing or out of range."},"402":{"description":"Payment Required"},"502":{"description":"The upstream source failed or timed out."}},"x-payment-info":{"price":{"mode":"fixed","currency":"USD","amount":"0.0200"},"protocols":[{"x402":{"network":"eip155:8453","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/three-phase-power"}},{"x402":{"network":"solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/three-phase-power"}},{"x402":{"network":"eip155:137","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/three-phase-power"}},{"x402":{"network":"eip155:42161","scheme":"exact","currency":"USDC","endpoint":"https://electrical-calc.x402tookit.com/three-phase-power"}}]}}},"/transformer-sizing":{"get":{"operationId":"transformer_sizing","summary":"Transformer kVA for a load with a stated margin, next common standard size, and primary and secondary full-load current.","description":"Transformer kVA for a load with a stated margin, next common standard size, and primary and secondary full-load current.","tags":["transformer","kva","sizing","electrical"],"parameters":[{"name":"loadKw","in":"query","required":true,"description":"Connected load in kilowatts","schema":{"type":"number"}},{"name":"secondaryVoltageV","in":"query","required":true,"description":"Secondary (line-to-line if three phase) voltage in volts","schema":{"type":"number"}},{"name":"powerFactor","in":"query","required":false,"description":"Load power factor above 0 to 1 (default 0.9)","schema":{"type":"number"}},{"name":"marginPct","in":"query","required":false,"description":"Spare capacity margin in percent (default 25, 0 to 200)","schema":{"type":"number"}},{"name":"phase","in":"query","required":false,"description":"single or three (default three)","schema":{"type":"string"}},{"name":"primaryVoltageV","in":"query","required":false,"description":"Primary (line-to-line if three phase) voltage in volts, for primary current","schema":{"type":"number"}}],"responses":{"200":{"description":"The answer.","content":{"application/json":{"schema":{"type":"object","properties":{"verdict":{"type":["null","string"]},"summary":{"type":["null","string"]},"reasons":{"type":["array","null"],"items":{"type":"string"}},"loadKva":{"type":["null","number"]},"requiredKva":{"type":["null","number"]},"selectedStandardKva":{"type":["null","number"]},"spareAtSelectedPct":{"type":["null","number"]},"phase":{"type":["null","string"]},"secondaryFullLoadCurrentA":{"type":["null","number"]},"secondaryCurrentAtRequiredKvaA":{"type":["null","number"]},"secondaryCurrentAtLoadA":{"type":["null","number"]},"primaryFullLoadCurrentA":{"type":["null","number"]},"turnsRatio":{"type":["null","number"]},"commonSizesKva":{"type":["array","null"],"items":{"type":"number"}},"degraded":{"type":["boolean","null"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"source":{"type":["null","string"]},"asOf":{"type":["null","string"]},"disclaimer":{"type":["null","string"]}}},"example":{"verdict":"SIZE_FOUND","summary":"80 kW at PF 0.8 is 100 kVA; with 25% margin 125 kVA, so choose the next common size, 150 kVA.","reasons":["Required kVA = 80 / 0.8 x (1 + 25/100) = 125.","Common three-phase sizes: 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750, 1000, 1500, 2000, 2500, 3750, 5000 kVA (typical values, not an exhaustive standard).","…1 more"],"loadKva":100,"requiredKva":125,"selectedStandardKva":150,"spareAtSelectedPct":50,"phase":"three","secondaryFullLoadCurrentA":416.3584,"secondaryCurrentAtRequiredKvaA":346.9653,"secondaryCurrentAtLoadA":277.5722,"primaryFullLoadCurrentA":180.422,"turnsRatio":2.307692,"commonSizesKva":[15,30],"degraded":false,"notChecked":["inrush current and overcurrent protection sizing","harmonic (K-factor) loads, temperature and altitude derating","…2 more"],"source":"computed locally (kVA = kW / PF x (1 + margin); I = kVA x 1000 / (V or sqrt(3) V))","asOf":"2026-10-21T06:22:29.239Z","disclaimer":"Screening signal computed from the named public source. 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