INSTALL GROUNDING ELECTRODES
Critical Task: 051-246-1104
In this lesson, you will learn to describe the procedures used to install grounding electrodes.
TERMINAL LEARNING OBJECTIVE:
You will learn to describe the procedures used to install grounding electrodes.
You will be given the material contained in this lesson. You will work at your own
pace and in your own selected environment with no supervision.
You will correctly answer the practice exercise questions at the end of this lesson.
REFERENCES: The material contained in this lesson was derived from STP 5-51R12-SM-TG and
Section 250 of the NEC.
An electrician's most important concern is to ensure that all electrical circuits are grounded. In this
lesson, you will be shown how to properly select and place grounding electrodes. As an electrician, you
must be able to install and test electrical circuits to ensure that you have a proper ground.
1-1. Systems. Grounding systems are installed using grounding rods, conductors, or plates. Grounding
rods must be copper, steel, or iron/steel (galvanized) pipe that is at least 8 feet long. Ground resistance
must be less than 25 ohms to ground (earth). In order to get resistance below 25 ohms to ground, you
may need to drive a ground rod deeper than 8 feet, install additional rods, or add chemicals to the soil.
Metal water pipes can be used to supplement a grounding system. One of the most important parts of
electrical installation is the grounding rod (Figure 1-1, page 1-2).