EMC Question of the Week: April 9, 2018
Which of the following statements about earth ground is generally true?
- all current ultimately flows to earth ground
- for safety reasons, all electronic systems require an earth ground
- ground conductors in a building's power distribution are connected to the earth
- all of the above
Answer
The correct answer is "c." The ground conductors in a building's power distribution system are electrically connected to the earth around the building. Residential buildings typically have a metal rod that is driven into the ground near the electrical service entrance to the building. A wire connects the rod to the building ground at the breaker box. Metal plumbing is also connected to ground at the breaker box.
The other choices are incorrect. Currents typically return to their source. They do not flow to earth ground unless they were drawn from earth ground. Many electronic systems have an earth ground connection for safety reasons; but many others don't. Specifically double-insulated products and low-voltage systems are unlikely to have an earth ground connection.
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