Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!


Electrical engineering with units, amps and electrical wiring. Wire gauges, electrical formulas, motors and more.

12 Volt - Electric Automotive Wiring

Maximum wire lengths vs. currents in the 12 volt electrical system of a car.

12 Volt - Maximum Wire Length vs. Current

Maximum length of copper wire with 2% voltage drop.

12 Volt - Wire Gauge vs. Amps

Maximum current (amps) in a 12V electrical circuit vs. size (AWG) and length of wire.

AC - Active, Reactive and Apparent Power

Real, imaginary and apparent power in AC circuits.

AC Circuits - Power vs. Voltage and Current

The alternating current In an AC circuit is generated by a sinusoidal voltage source.

Aluminum and Copper Wires - Electrical Resistance vs. Cross-Sectional Area

Electrical resistance in plain copper or aluminum wires.

Aluminum Conductor Characteristics

Characteristics of all-aluminum conductors (AAC).

Asynchronous Induction Motors - Electrical Properties

Typical electrical motor data like nominal current, fuse, start ampere, size of contactor and circuit breaker - for asynchronous induction motors.

AWG - American Wire Gauge Converting Chart

American Wire Gauge (AWG) vs. cross sectional area converter.

AWG - American Wire Gauge Current Ratings

Amp ratings vs. US AWG wire gauges.

AWG - American Wire Gauge vs. Circular Mils

AWG vs. diameter mil, circular mil, diameter in mm and area in mm2.


Capacitors and capacitance - charge and unit of charge.

Capacitors - Parallel and Serial Circuits

Parallel and serial connected capacitor circuits.

Capacitors - Stored Energy

Potential power and energy stored in capacitors.

CE Marking

Verifies that a product is designed to the appropriate standards according the European Machine Directive.

Circles within a Rectangle - Calculator

Calculate the maximum number of circles within a rectangle - can be used to calculate the numbers of pipes or wires in a conduit or similar.

CM - Circular Mil Area

The circular mil area (CM) unit denotes the cross-sectional size of a wire or a cable.

Copper and Aluminum Wire - Max Amps vs. Gauge

Maximum current in copper and aluminum wire.

Copper Wire - Electrical Resistance vs. Gauge

Gauge, weight, circular mils and electrical resistance in copper wire.

Coulomb's Law

The electric force acting on a point charge.

Current Divider - Online Calculator

An electric current divider outputs a current that is a fraction of the input current.

Dielectric Strength of Insulating Materials

The dielectric strength of a material is the ability to the material to act as an insulator.

Electric Cable Size vs. Current Rating

Amps vs. cable size for fixed installations in buildings.

Electric Circuit Diagram - Drawing Template

Online shareable electric circuit diagram.

Electric Circuits Voltage Drop

Ohm's law and voltage drop in electric circuits.

Electric Heating of Mass

Electric heating of an object or mass - temperature change vs. energy supplied.

Electric Motor Calculator

Calculate amps, hp and kVA for electrical motors.

Electric Motors - 230 & 460V Three Phase Circuits Wiring

Sizing of copper wire and transformers for three phase 230 & 460V electrical motors.

Electric Motors - 480 Volt Wiring

480V electrical motor wiring data - NEMA amps, starter size, HMCP size for motors ranging 1/2 to 500 hp.

Electric Motors - Efficiency

Calculate electric motor efficiency.

Electric Motors - IEC and NEMA Standard Torques

IEC and NEMA torque classifications of electrical motors.

Electric Motors - Torque vs. Power and Speed

Electric motor output power and torque vs. rotation speed.

Electric Shocks

The physiological effects of electric shocks.

Electric Wire - Calculating Cross-Section Areas

Calculate single and bunched electric wire cross-section area and diameter.

Electric Wire - Maximum Length with 240 Volts Single-Phase Power

Maximum length of 240 V single phase electric wire with max. 2% voltage drop.

Electric Wire - Resistance

Electric resistance in wire made of Copper, Aluminum, Brass, Constantan, Nichrome, Platinum, Silver or Tungsten.

Electrical Conductivity - Elements and other Materials

Electric conductance is the ability of a element to conduct an electric current.

Electrical DC Motors - Full-load Currents

Full load amps in 120 and 240 volts electrical DC motors.

Electrical Distribution Systems

Electrical distribution systems commonly used in Europe and USA

Electrical Enclosure Types by NEMA

Description of NEMA electrical enclosures types.

Electrical Formulas

Commonly used electrical formulas like Ohms Law and more.

Electrical Inductance - Serial and Parallel Connections

Electrical inductance in serial and parallel connected inductors.

Electrical Induction Motors - Slip

Slip is the difference between an electrical induction motor's synchronous and asynchronous speed.

Electrical Induction Motors - Synchronous Speed

Operating speed of an induction motor depends on the input power frequency and the number of magnetic poles in the motor.

Electrical Induction Motors - Torque vs. Speed

Full load operating torque vs. break down, pull up and locked rotor torque.

Electrical Metal Tubing (EMT) - Conduits

Trade sizes and max. distance between conduit supports.

Electrical Motors - Frame Dimensions

Electrical motors NEMA frame dimensions.

Electrical Motors - Full Load Amps

Full load amps for single and 3-phase 460 volts, 230 volts and 115 volts electric motors.

Electrical Motors - Heat Loss

Heat loss from an electrical motor to the surroundings.

Electrical Motors - Horsepower vs. Voltage and Amps

Electrical motors horsepower rating vs. their ampere rating.

Electrical Motors - Insulation Classes

Electrical motors NEMA temperature and insulation classes.

Electrical Motors - Locked Rotor Design Code Letters

NEMA locked rotor indicating code letters for electrical motors.

Electrical Motors - Maximum Cable Size and Length vs. Power

Maximum electrical motor cable length vs. power.

Electrical Motors - NEMA Frame Assignments

NEMA frame assignments.

Electrical Motors - Service Factors

Service factor - SF - is a measure of periodically overload capacity at which a motor can operate without beeing damaged.

Electrical Motors - Shaft Power vs. Voltage and Current

Calculate electric motors shaft power.

Electrical Motors - Single Phase 230 V Circuit Wiring

Copper wire gage and transformer size for single phase 230 volts electrical motors.

Electrical Motors - Speed at Operating vs. Synchronous Load

Speed of an operating electrical motor with load is lower than the synchronous speed (no load) of the motor.

Electrical Motors - Speed vs. No. of Poles and Frequency

The speed of electrical motors with 2, 4, 6 or 8 poles at 50 Hz and 60 Hz.

Electrical Motors Efficiency Ratings

NEMA - electrical motor efficiency ratings.

Electrical Parallel Circuits

Resistance, voltage and current in electrical parallel circuits.

Electrical Resistance in Serial and Parallel Networks

Resistors in parallel and serial connections.

Electrical Series Circuits

Voltage and current in electrical series circuits.

Electrical Units

Definition of common electrical units - like Ampere, Volt, Ohm, Siemens.

Electrical Vehicle Charging - Power vs. Voltage and Amps

EV Charging - AC vs. DC, single phase vs. three phase and power vs. voltage and amps.

Electrical Voltage and Frequency Standards by Country

Typical voltages and frequencies used for domestic appliances in different countries.

Electromotive Force - e.m.f

Change in electrical potential between two points.

Electrotechnical Abbreviations

Abbreviations according the International Electrotechnical Commission (IEC).

Extension Cords - Load Rating vs. Wire Gauge and Length

Size of extension cords - full load ratings with 115 V.

Galvanic Corrosion vs. Electrode Potential

Introduction to electro chemical series and corrosion of metals.

IEC Electric Motor Duty Cycles

The eight - S1 - S8 - IEC duty cycles of operating electrical motors.


The Electro Magnetic Field - EMF - induced into a electric circuit.

Induction Motors - No. of Poles and Synchronous vs. Full Load Speed

Synchronous and full load speed of amplitude current (AC) induction motors.

Inductors - Stored Energy

Energy stored in a magnetic field.

Intermediate Metal Conduit - IMC

Lighter and lower cost metal conduits.

IP - Ingress Protection Ratings

IP - Ingress Protection rating is used to specify the environmental protection - or electrical enclosure - of electrical equipment.

Kirchhoff's Voltage and Current Laws

Kirchhoff's current and voltage laws.

LENI - Lighting Energy Numeric Indicator

Energy consumption of lighting systems

Lights vs. Power Installation

Lights vs. power installations in common types of buildings and rooms.

Ligths - Color Temperatures

Light sources and their color irradiation in degrees Kelvin.

Luminous Efficacy

The visible light produced by light sources.

NEMA - National Electrical Manufacturers Association

National Electrical Manufacturers Association.

NEMA A, B, C and D Electrical Motor Design

NEMA has established the four different designs A, B, C and D for electrical induction motors.

NEMA and IEC Enclosure Classifications

NEMA enclosure classifications versus IEC enclosure classifications.

NEMA Enclosure Standards for Electric Motors

NEMA enclosure standard for electrical motors.

NEMA Insulation Classes

Electrical insulation systems rated by standard NEMA classifications to maximize allowable operating temperatures.

Nema Starters

Nema sized contactors or starters.

Nickel-Chromium Heater Wire - Temperature Rise vs. Amps

Electric resistance vs. temperature rise for Nickel-Chromium electrical heater wire.

Ohm's Law

The relation between voltage, current and electrical resistance.

Online Wire Gauge - AWG - Calculator

Calculate AWG, mil, mm, CM or square mm.


Electromagnetism and formation of magnetic fields.

Polyphase Motors - Voltage Imbalance vs. Derating Factor

Increased voltage imbalance and decreased efficiency.

Power Installations - DIN VDE Standards

DIN VDE power installation standards.

Power Wiring - Color Codes

Color codes used in power wiring.

Rechargeable Batteries - Properties and Life Calculator

Properties of rechargeable batteries and accumulators.

Relative Permittivity - the Dielectric Constant

Common materials and their relative permittivity.

Relative vs. Absolute Voltage

Electric circuits and voltage at any point.

Resistance vs. Conductance

The reciprocal of electrical resistance is conductance.

Resistance vs. Resistivity

Electrical resistance and resistivity.

Resistivity and Conductivity - Temperature Coefficients Common Materials

Resistivity, conductivity and temperature coefficients for common materials like silver, gold, platinum, iron and more..

Resistors - Color Codes Calculator

Color codes for fixed resistors - values and tolerances - online calculator.

Resistors - Letters and Digit Codes

Letter and digit codes to indicating resistor values.

Resistors - Standard Values

Preferred number series for resistors.

Rigid Aluminum Conduit - RAC

Rigid Aluminum Conduit dimensions.

Single and Three Phase AC - Electric Current vs. Power

Convert between single phase (120, 240 and 480 Voltage) and three phase (240 and 480 Voltage).

Single Phase Power Equations

Power equations for single phased electrical systems.

Smaller Circles within a Large Circle - Calculator

Calculate the number of small circles that fits into an outer larger circle - ex. how many pipes or wires fits into a larger pipe or conduit.

Soil - Electrical Resistivity

Types of soil and resistivity.

SWG - Standard Wire Gauge

Imperial Standard Wire Gauge used with wire and sheet metal.

Three-Phase Electrical Motors - Power vs. Amps and Voltage

Full load amps, wire and conduit sizes for three phase electrical motors.

Three-Phase Electrtical Motors - Power Factor vs. Inductive Load

Inductive loads and power factors with electrical three-phase motors.

Three-Phase Power - Equations

Electrical 3-phase equations.

Transformers - kVA Ratings vs. Volt and Amps

Alternating voltage and induced electro magnetic field - e.m.f. - in a transformer.

Transient Spikes

A transient is a high voltage spike caused by an external or internal transient source

Voltage Dividers - Online Calculator

Output voltage potential divider.

Voltage Sources vs. Current Sources

Voltage and Current Sources

Wire Size - Area to Diameter Converter

Convert wire area from square mm to diameter mm.


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