The Function and Importance of Earth Grounding Systems – Part Two
In part one, we took a look at what earth grounding systems are and why they are so vitally important. We also briefly noted how as home inspectors, thorough home inspector training can help you better serve your clients and grow your business by fully understanding systems like these.
In this post, we are turning our attention toward some common issues with earth grounding systems.
What Goes Wrong with Earth Grounding Systems
Let’s look at what goes wrong with earth grounding systems. The implications are the same throughout. An ineffective or missing earth grounding system cannot perform its safety functions. There is greater risk of electrical shock, fire, and equipment damage in houses where the earth grounding system is not effective.
Things that can go wrong include:
- No grounding
- Ground wire is attached to plastic pipe
- Ground wire is after (downstream of) meters and valves, with no jumper
- Spliced ground wire
- Ground wire is attached to abandoned pipe
- Poor connections
- Ground connections are not accessible
- Ground rod is cut off
- Corroded ground wire
- Undersized ground wire
Next, we’ll discuss three of the most common conditions with earth grounding systems.
A missing earth grounding conductor (wire) is a result of improper installation. If it is missing, recommend immediate improvements. Clients, real estate agents, and homeowners may have a tough time understanding how this is important since the house has been operating this way for a long time. Explain that this is an emergency safety system and houses can operate for years without it, but the one time they need it, they won’t have the protection they should. The good news is it is typically not an expensive improvement.
There is no ground wire coming out of the main disconnect part of this panel.
Ground Wire Downstream of Meters and Valves with No Jumper
Make sure the ground wire is connected as close as possible to the plumbing service entry, and upstream of (before) any devices that might interrupt it. Where there are devices such as meters or pressure regulators upstream, a jumper should be added around the devices, or the ground wire should be moved upstream of these. The jumper should be the same size as the ground wire and clamped securely to the metal pipe.
Metal natural gas piping must be bonded to the grounding system. This applies to new installations as well as updates involving gas piping or electrical service work. It is common to find this bonding wire connected to the plumbing system at the water heater, where the gas and water pipes are close together. In this case, a jumper may be needed around the water meter to maintain continuity of bonding for the gas piping (although the electrical system may be properly grounded without this jumper).
A jumper wire is needed here.
Loose or Poor Connections
Loose or poor connections are caused by a few things, such as:
- Poor installation
The ground wire (earth grounding electrode) is typically connected to the service box at one end and to a pipe and/or ground rod(s) at the other. Make sure the wire is securely fastened at both ends. Where ground wires are attached to pipes, it’s not adequate to just wrap the wire around the pipe. The wire must be secured with a clamp approved for that purpose.
The wire should be tight in the clamp, and the clamp should be tight on the pipe. Corrosion of the wire, clamp, or pipe can result in poor connections. Where you see this, recommend further investigation or improvement as appropriate.
Electrical tape is not a proper way to connect a ground wire to the electrode.
We have introduced earth grounding systems in this discussion, and touched on some of the common issues. More information regarding other conditions, their causes, implications and strategies for inspection can be found in our high-quality home inspector training program.