Grounding to Water Pipes- Electrical Inspections- Wenatchee and Quincy Home Inspections
When performing a home inspection and evaluating the electrical system I am always trying to confirm if a grounding system is proper.
The Washington State Home Inspector Standards of Practice states (WAC 308-408C-110 Electrical system.)-
A home Inspector must:
(b) Report (i) The existence of a connected service-grounding conductor and service-grounding electrode when same can be determined. (ii) When no connection to a service grounding electrode can be confirmed.
The purpose of the grounding electrode is to be connected to earth and to the electrical equipment so it establishes a zero difference of potential between the earth and the electrical equipment. This zero difference of potential helps stabilize voltage for the electrical system.
In addition the grounding electrode system is used to limit the voltage imposed on the electrical system by lightning, line surges, or unintentional contact with higher-voltage lines.
Now during a home inspection it may not be easy to locate and I may not find it. Grounding electrodes can be buried and often not visible.
In many older homes it is common to use the water pipe as the primary grounding electrode. But often not within 5 feet of the entrance of the home.
The National Electrical Code states (per 2005/2008 NEC)-
250.52 Grounding Electrodes. (A) Electrodes Permitted for Grounding.
(1) Metal Underground Water Pipe. A metal underground water pipe in direct contact with the earth for 3.0 m (10 ft) or more (including any metal well casing bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Interior metal water piping located more than 1.52 m (5 ft) from the point of entrance to the building shall not be used as a part of the grounding electrode system or as a conductor to interconnect electrodes that are part of the grounding electrode system.
There is a good reason for the 5 foot rule. Often in these older homes the plumbing has been modified and replaced with materials that are not conductive such as plastics. Also you want to make sure that if you have a removable component such as a pressure reducing valve or meter etc… that you do not lose ground during replacement or servicing.
Here we have a perfect example of why this rule is so important. On this home inspection I found the ground has been severed when re-piping was performed. This home is now without a ground and is a safety issue.
Being “Grounded” is always a good thing.
“A shocking occurrence ceases to be shocking when it occurs daily. “
NCW Home Inspections, LLC is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…
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