WiremanWireman · Ground rod or electrode problems: troubleshooting for electricians · 2023 NEC ·
Ground rod or electrode problems
Bad clamps, short rods, one rod or two, and what the 25 Ω rule really means.
Before you start
How much electrical experience do you have?
This sets how much detail each step shows. You can change it any time.
Showing detail
How it works
The grounding electrode connects the system to the earth. It limits voltage from lightning, utility surges and contact with higher-voltage lines. It does not clear faults: the earth has far too much resistance to trip a breaker, which is the job of the equipment grounding conductor and the neutral-to-ground bond at the service. A rod is one kind of electrode; footing steel, metal water pipe and ground rings are others, and every one present must be bonded together.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What’s the problem?
- Connection is loose, corroded or brokenTest: Clamp it, then inspect itExpect: Near 0 A, a tight listed clamp and an unbroken conductor.
- Clamp loose, corroded or the wrong typeBad clamp or connection
- Conductor cut, broken or missingGrounding electrode conductor broken or missing
- Connection looks goodHow many rods are there?
- Two rods at least 6 ft apart, bonded togetherTwo rods meet the code
- Two rods closer than 6 ftRods too close together
- One rodTest: Measure the rod’s resistance to earthExpect: 25 Ω or less means one rod meets the code by itself.
- 25 Ω or lessOne rod is enough
- More than 25 ΩSingle rod over 25 Ω
- Readings jump aroundProbe placement or interference
- Is one rod good enough?How many rods are there?
- Two rods at least 6 ft apart, bonded togetherTwo rods meet the code
- Two rods closer than 6 ftRods too close together
- One rodTest: Measure the rod’s resistance to earthExpect: 25 Ω or less means one rod meets the code by itself.
- 25 Ω or lessOne rod is enough
- More than 25 ΩSingle rod over 25 Ω
- Readings jump aroundProbe placement or interference
- Rod sticks out or wasn’t driven all the wayCan the rod be driven the rest of the way?
- Yes, it just wasn’t finishedRod not fully driven
- It hits rockRock bottom
- A fault didn’t trip; it only has a ground rodEarth is not a fault path
- Connection is loose, corroded or brokenTest: Clamp it, then inspect itExpect: Near 0 A, a tight listed clamp and an unbroken conductor.