A grounding inspection is designed to ensure the electrical system is properly grounded as a safety precaution. This means that a portion of the wiring in the main panel box must be connected to the ground. An electrical ground system is done by connecting the wiring to a grounding wire, that in turn is clamped to a metallic inlet water pipe or to a rod driven into the ground.
During an inspection of the grounding, check to see if the electrical ground has been properly connected. There should be a wire coming out of the main panel box that runs to the inlet water pipe. If the wire is not visible, go directly to the inlet water pipe. This pipe is located by the water meter, if there is one, and it usually protrudes through the foundation wall or lower-level floor slab.
The electrical ground wire should be clamped to the water pipe on the street side of the water meter. Sometimes, you may find it connected on the house side, but in such cases there should also be a jumper cable running around the meter to the street side.
Hazards and Safe Grounding System – How to Spot Improper Ground Connections
An incredibly large number of houses have loose clamps on the water pipes, resulting in an improperly grounded electrical system. Many homeowners are not aware that the wire clamped to the water pipe is a grounding wire for the electrical system and they often loosen the clamp when making a repair or finishing the basement. Because nothing obvious happens when the wire is disconnected, homeowners often forget to re-clamp it when they’re done with the repair.
During the grounding inspection, look at the clamp and check if it’s loose. If it is, it must be re-secured. This is easy to do, and generally all you need is a screwdriver. In some cases, however, the clamp or screws have corroded and must be replaced. If there is no clamp or ground wire visible, the integrity of the ground system might have been compromised.
Sometimes, the ground wire is clamped to a water pipe other than the inlet pipe, but this can only give a false sense of security because a section of the pipe can be removed, causing an open circuit in the electrical ground. In some states, a jumper wire is required between the hot- and cold-water pipes that are connected to the tank-type water heater. This provides electrical bonding between the two pipes and prevents an interruption in the ground circuit when the water heater is being replaced. In addition, some states may also require a jumper wire around the water meter, if any, and also around a plastic water filter in the main water line, if there is one. These requirements can be checked with local authorities.
It is essential that the inlet pipe to which the electrical ground is connected is a functioning water pipe. This ensures that the pipe extends a considerable distance into the ground – according to the electrical code it should extend at least ten feet into the ground. If a new inlet water pipe has been installed, the ground wire should be moved to the new pipe. Usually, when replacing an old water pipe, the portion outside the structure is cut off at the foundation wall.
If the inlet water pipe is plastic, as it often is the case with a well, the electrical ground system is achieved by connecting the grounding wire to a rod driven into the ground. If this is the case, during your inspection of the grounding you should check the clamp connection and the rod. If wither the clamp or rod is loose, the integrity of the electrical ground system may be compromised.