READOS / Engineering / KEVOS® original book
Industrial Electric Heating by the Numbers
Joule heating, conductors, cables and fuses, heating elements, ovens, furnaces, induction, control and cost, from the 1895 handbook to the modern workshop
Design, size and run electric process heating from first principles: Joule heating, conductor and cable temperatures, fuses, elements, ovens, furnaces, induction, control and cost.
Start readingAbout this book
Electric heat is everywhere in industry: the oven that cures powder coating, the furnace that tempers springs, the induction coil that hardens a shaft, the heater that keeps an oil tank fluid, the band heaters on an injection moulding barrel. Every one of them turns electrical energy into heat in a resistance, and every one of them can be understood, sized and checked with a handful of relationships that were already well understood in 1895.
This book is for manufacturing and maintenance engineers, plant managers, technicians and students who specify, size, run or troubleshoot electric heating equipment. It assumes basic electricity, heat and algebra in SI units. It does not teach electrical installation work, which in Australia must be done by licensed electricians to the Wiring Rules, and it does not replace equipment makers’ data. It explains, with numbers, where the heat comes from, where it goes, and what it costs.
An 1895 handbook as a starting point
Electric Heating, by Edwin J. Houston and A. E. Kennelly, was published in New York in 1895 as part of their Elementary Electro-Technical Series, written to give the general public reliable information about electricity. Kennelly went on to become one of the leading electrical engineers of his generation. Their small book covered the principles of electrical heating, the heating of bare and covered wires, fuses, electric heaters and cooking, electric welding and electric furnaces, at a time when most of these were new.
Their numbers can be checked, and most of them hold. Their resistivity for copper, their temperature coefficient for pure metals, their electric kettle and their estimates of the energy to heat a steel bar are all close to modern values. Each chapter of this book takes one of their themes, checks it and applies it to a modern case.
The running case
This is an illustration. A fabrication and coating business is installing an electric batch oven to cure powder coating on steel frames and brackets, and a small electric furnace for tempering springs and tool steel parts. Through the book, its engineer works out the oven’s heaters, supply, warm-up and running costs, checks its cables and protection, designs a heating element, sizes the tempering furnace, looks at induction and infrared alternatives, sets up the control, and compares electric heat with gas.
The business, the oven, the furnace, their dimensions, settings and costs are invented for teaching. They are not KEVOS® work, and they are not designs for any equipment. Real equipment is designed by its makers to the applicable standards and installed by licensed electricians.
How to use the book
Chapters 1 to 4 cover the electrical side: Joule heating and energy, resistance and temperature, how conductors heat and cool, and cables and fuses. Chapters 5 to 8 cover the equipment: heating elements, ovens, furnaces, and induction and infrared heating. Chapter 9 deals with control and Chapter 10 with safety, cost and the choice between electric and gas heat. Every chapter ends with an exercise and its worked answer.
Limits and professional responsibility
This book is educational. Electrical installation and repair work must be done by licensed electricians in accordance with AS/NZS 3000 and the regulator’s requirements, and electrical risks must be managed in line with Safe Work Australia’s model code of practice on managing electrical risks in the workplace as adopted in each jurisdiction. Ovens and furnaces present burn, fire and, with some coatings and processes, fume and explosion hazards that their makers’ instructions and the work’s risk assessment must address. The 1895 practices are described as history, not practice.
An original treatment
READOS covers heating of buildings in its HVAC collection and resistance welding in Resistance Welding by the Numbers. This book covers electric heating of materials and processes. The explanations, the oven and furnace case, the calculations, figures and exercises are original KEVOS® writing. The 1895 handbook is a public-domain work in the United States; its facts are summarised, checked and corrected in new words, and none of its text, tables or illustrations is reproduced.
Who this book is for
Manufacturing and maintenance engineers, plant managers, technicians and students who specify, size, run or troubleshoot electric ovens, furnaces, heaters and induction equipment.
What you will learn
- Calculate the heat produced by a current in a resistance and the temperature a conductor reaches as it loses heat to its surroundings.
- Explain why cables and fuses are sized as they are, and estimate the heat in a conductor or a busbar.
- Size a resistance heating element from its power, voltage, alloy and surface loading.
- Build the heat balance of an electric oven or furnace and size its heaters and warm-up time.
- Compare resistance, induction and infrared heating, control them sensibly and cost electric heat against gas.
Inside this book
Chapters
- 01Joule heating, power and energyUse P = VI = I²R = V²/R for single- and three-phase heaters, check the 1895 electric kettle, and turn an oven's power into energy, demand and cost per day.
- 02Resistance and temperatureCalculate a conductor's resistance from its resistivity and size, see how much copper's resistance rises when it heats, and why heating elements are made from nickel-chromium alloys instead.
- 03How conductors heat and coolBalance the heat a conductor makes against the heat it loses by convection and radiation, find its steady temperature and time constant, and see why a heating element needs its surroundings.
- 04Cables, fuses and protectionSee why a cable's current rating is really a temperature limit, estimate how hot a conductor gets during a short circuit, and understand how fuses and circuit breakers protect the wiring of a heater.
- 05Designing heating elementsSize a resistance heating element from its power and voltage: resistance, wire length, diameter and surface loading, and why a thicker wire runs so much cooler and lasts longer.
- 06The oven heat balanceAccount for every kilowatt an electric curing oven uses: product, racks, walls, exhaust, doors and warm-up, then work out how long the thickest part takes to reach curing temperature.
- 07Furnaces and radiationSee why radiation takes over as furnaces get hotter, size a small electric tempering furnace, check the 1895 figures for heating steel bars, and place the thermocouple where it tells the truth.
- 08Induction and infrared heatingHeat steel inside itself with induction, choose a frequency from the depth of penetration, size the power to heat a bar end, and use infrared emitters to heat surfaces by radiation.
- 09Controlling electric heatHold an oven at temperature with on/off, time-proportioning and PID control, keep an independent over-temperature limit, and stage heaters to limit peak demand.
- 10Safety, cost and choosing electric heatManage the electrical, burn and fire hazards of electric heating, cost a year of oven operation including demand charges, and weigh electric heat against gas on more than the price per megajoule.
References and source notes
The manuscript and worked examples are original KEVOS® writing. References inform particular concepts; their authors do not endorse this book. Web references were consulted on 25 October 2026.
- Edwin J. Houston and A. E. Kennelly (W. J. Johnston Company, New York). Electric Heating (Elementary Electro-Technical Series) (1895). Historical source for the 1895 treatment of the conversion of electrical energy to heat, resistivity and its temperature coefficient, heating of bare and covered conductors, fuse wires, electric heaters and cooking, electric welding and furnaces, including the electric kettle and bar-heating examples. Summarised and checked in new words; no text, tables or illustrations are reproduced.
- Kanthal. Nickel-chromium (NiCr) resistance wire alloys, including Nikrothal 80 (manufacturer data). Source for the resistivity of an 80/20 nickel-chromium heating alloy at 20 °C (1.09 Ω·mm²/m), its maximum continuous operating temperature in air (1,200 °C), its small temperature factor of resistivity, density and melting point, used in Chapters 2 and 5 as one maker's data.
- Safe Work Australia. Model Code of Practice: Managing electrical risks in the workplace (model code). Cited in Chapters 4 and 10 as the national model guidance on electrical risk. Check which version applies in your jurisdiction.
- Standards Australia and Standards New Zealand. AS/NZS 3000, Electrical installations (Wiring Rules); AS/NZS 3008.1.1, Electrical installations, selection of cables (current editions). Named in Chapters 4 and 10 by number and scope. No content or values are reproduced; electrical installation work must be done by licensed electricians to these standards.
