https://elec.webpenson.com/en/ Recent content in Electrical Toolbox — Free Online Electrical Calculators on Electrical Toolbox Hugo en-US Sun, 19 Jul 2026 00:00:00 +0000 https://elec.webpenson.com/en/tools/transformer-capacity-selection/ Sun, 19 Jul 2026 00:00:00 +0000 https://elec.webpenson.com/en/tools/transformer-capacity-selection/ Online transformer capacity selection calculator. Enter power kW, power factor cosφ, efficiency η, and load factor β to quickly estimate required transformer kVA capacity. Recommends GB/T 17468 R10 standard ratings. Supports single-equipment / multi-equipment diversity factor / motor starting current correction. For engineering design, factory distribution, and design institute calculation sheets. https://elec.webpenson.com/en/tools/cable-current-carrying-capacity-lookup/ Sat, 18 Jul 2026 21:05:00 +0000 https://elec.webpenson.com/en/tools/cable-current-carrying-capacity-lookup/ Online cable ampacity lookup tool supporting YJV / YJLV / VV / VLV / BVR / BLVR and other cable types. Covers 5 installation methods: free-air, conduit, tray, direct burial, and duct. Automatically applies GB 50217 temperature, grouping, and altitude correction factors. For electrical engineering design, on-site construction, and factory maintenance. https://elec.webpenson.com/en/about/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/about/ About Electrical Toolbox — free online electrical calculation tools for engineers and EV owners https://elec.webpenson.com/en/tools/charging-time-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/charging-time-calculator/ Free online charging time calculator. Enter battery capacity kWh, charging power kW, and efficiency to estimate 0–100% / 50–80% / 0–80% charging duration. Covers 13 EV charger presets (7/11/22/43kW AC + 30/60/80/100/120/160/240/400/480kW DC). https://elec.webpenson.com/en/tools/circuit-breaker-sizing-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/circuit-breaker-sizing-calculator/ Free NEC-aware circuit breaker calculator. Enter amps or kW, get the OCPD per NEC 240.6(A) + 240.4(B) + 125% rule. EV, subpanel, motor presets. No signup. https://elec.webpenson.com/en/tools/electricity-cost-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/electricity-cost-calculator/ Free online electricity cost estimator. Enter appliance wattage W and daily usage hours (or monthly kWh) plus electricity rate ¥/kWh to calculate daily/monthly/annual costs. Includes presets for LED lights, refrigerators, air conditioners, and water heaters. Assists with household energy savings. https://elec.webpenson.com/en/tools/charging-power-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/charging-power-calculator/ Free online EV charger power calculator. Enter voltage V, current A, and power factor cosΦ to calculate active power kW, reactive power kVar, and apparent power kVA. Supports single-phase 220V and three-phase 380V, assisting with charger sizing. https://elec.webpenson.com/en/tools/three-phase-power-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/three-phase-power-calculator/ Online three-phase power and power factor calculator. Enter line voltage V, line current A, and power factor cosφ to calculate active power P(kW), apparent power S(kVA), and reactive power Q(kvar). Supports unit switching (W↔kW, VAr↔kVAr) and recommends reactive power compensation capacitors to correct to 0.95. For factory distribution, motor sizing, transformer capacity verification, and reactive power penalty calculations. https://elec.webpenson.com/en/tools/wire-size-calculator/ Mon, 01 Jan 0001 00:00:00 +0000 https://elec.webpenson.com/en/tools/wire-size-calculator/ Free NEC-aware wire size calculator. Enter amps, voltage, distance & material — get AWG/kcmil with ampacity + 75 °C correction in seconds. No signup.