NATE Gas Heating Practice Exam

Approximately how many volts create a spark in a spark ignition system?

1. 240 volts

2. 5,000 volts

3. 15,000 volts

4. 25,000 volts

The correct answer is: 15,000 volts

In a spark ignition system, the voltage required to create a spark is typically around 15,000 volts. This high voltage is essential because it needs to overcome the insulation resistance of the air gap in the spark plug to ionize the air and create a conductive path, allowing the electricity to jump across to generate a spark. This spark ignites the air-fuel mixture in the combustion chamber, facilitating the engine's operation. The choice of 15,000 volts accurately reflects the standard operating conditions in many residential and commercial gas heating applications where effective and reliable ignition is crucial. While lower voltages exist in some ignition systems, they usually do not provide sufficient energy to create a reliable spark, which can lead to ignition failure or incomplete combustion. Higher voltages, like 25,000 volts, although used in some specialized applications, are not the standard for typical residential systems. Understanding this voltage range is important for technicians to ensure proper functioning of gas heating systems.