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Free transformer tools
Calculators and lookups for the numbers that come up when specifying a pad mounted transformer. Free, no sign up, free to cite.
kVA to amps calculator
Three phase full load current at 480Y/277, 208Y/120, 240, 600 and medium voltage primary, plus a printed table for every standard rating.
Transformer sizing calculator
What size transformer a service needs. Enter amps and voltage and get the kVA, the smallest standard rating that covers it, and the 80 percent continuous figure.
Transformer scrap value calculator
How much copper or aluminium is actually in a decommissioned unit and what it is worth, with the winding, core, tank and oil split out by weight.
Copper wire scrap calculator
Copper pounds in Romex, THHN and bare wire by the foot or the pound, recovery from spec sheet weights, yard grades and whether stripping pays.
Three phase transformer formulas
Full load current, kVA from amps, kW, turns ratio, primary current and fault current, each with a worked example, plus a kVA to amps chart.
kVA to kW calculator
Convert apparent power to real power using power factor, with full load current alongside, and why transformers are rated in kVA rather than kW.
Grow light circuit calculator
How many grow lights fit on a 15 to 50 A circuit at 120, 208, 240 and 277 V, amps per HPS, CMH and LED fixture, and the monthly kWh and cost.
kW to amps calculator
kW to amps and amps to kW for three phase, single phase and DC at any voltage and power factor, with amps per kW and charts from 1 to 2500 kW.
HP to kVA calculator
Motor horsepower to kVA, kW, kVAR and amps from efficiency and power factor, with a chart from 1 to 500 HP and the transformer size for a running motor.
kW to MW converter
kW to MW, kWh to MWh and kVA to MVA, the difference between power and energy, and a table of common transformer ratings in MVA.
Buck boost transformer calculator
Size a buck boost transformer from supply voltage, load voltage and load amps, with sizing charts for 208 to 240, 208 to 230, 240 to 208, 240 to 277 and 480 to 440 volts.
Reference tables
Well pump amps, wire size and breaker size
Amps by horsepower at 115, 230 and 460 V, breaker and wire sizes, and run lengths computed for 3 percent drop.
Wire ampacity chart
NEC Table 310.16 for copper and aluminum at 60, 75 and 90°C, with correction factors and the terminal rule.
NEMA enclosure ratings
Types 1, 3R, 4, 4X and 12 compared, with the IP codes three published charts give.
MVA transformer sizes
Full load amps from 1 to 100 MVA at 4.16 to 138 kV, with price and lead time benchmarks.
Motor full load amps chart
NEC Table 430.250 and 430.248 amps from 1/2 to 500 HP, with wire, breaker and kVA by horsepower.
Breaker size chart
Every standard breaker size from 10 to 6000 A with copper and aluminum wire sizes and the 125 percent rule.
Wire size by amps
The wire size for every rating from 15 to 4000 A, the 83 percent dwelling rule and parallel sets, with a calculator.
Primary distribution voltages
4.16 to 34.5 kV with phase to ground values, insulation class and BIL.
Power transformer prices
Price per MVA benchmarks from 5 to 300 MVA, price moves since 2020 and lead times.
Charts library
Every lookup table on the site in one index, from wire ampacity to service sizes.
Data center power equipment
Padmount transformers and the gear around them for server halls and colocation sites.
Buying used transformers
What to check before buying a secondhand or surplus unit.
Buying used switchgear
What to check on secondhand and surplus switchgear before it goes on a pad.