testing water pipe ground to 25 ohms for home inspector

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Stevenfyeager

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United States, Indiana
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electrical contractor
A home inspector wrote: "Verify water pipe grounded, with 25 ohms or less at water heater" How do I measure this? Do I test resistance between the water line at water heater and the outside ground rod? or the ground bar in the panel? Thank you
 
Honestly you should ask the inspector how it should be measured. What does this ("Verify water pipe grounded, with 25 ohms or less at water heater") even mean?
 
Stevenfyeager said:
A home inspector wrote: "Verify water pipe grounded, with 25 ohms or less at water heater" How do I measure this? Do I test resistance between the water line at water heater and the outside ground rod? or the ground bar in the panel? Thank you
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As Infinity said, ask him what this testing is supposed to accomplish- he might be misunderstanding the requirements and he is one of those that believes that GE testing is necessary, just tell him you can legally pound two rods along with the pipe GE and leave- the second rod eliminates the need for the 25 or less test for a single ​rod- see 250.53(A)(2) exception in the '14.

ETA: Also see 250.52(A)(1) and 250.53(D) for water pipe electrodes requirements and note the lack of required resistance testing for that type of electrode.......
 
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Make sure there are two ground rods and the water pipe is bonded. That is all you need to do. If this is an older home then the requirement for two rods may not have even been in effect.
 
It is clear that the home inspector is not a qualified electrical inspector and is probably following a checklist provided by their company. That being the case I think that I would just bust out the multi-meter and read resistance from the ground screw at the water heater to the union at the water connection. Guaranteed to be less than 25 ohms and you will not get into the weeds with earthing or supplemental grounding or sighting code language that may go right over their head.
 
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