Okay, this is a wood building without sprinklers. The water was brought in and distributed with plastic lines. The hot water heater has copper inlets but not to accept ground clamps without adding copper nipples. Where should we derive the secondary ground? I think we are going to face this more and more with new "cheaper" construction. Another ground rod is contra indicated per code. The inspector wants another ground rod for a ground. This inspector has already required things that are not code, ie extra EM lights and fire strobes in every room (small rental offices (10' X 10'). Give me some good news
Grounding new service with plastic water lines
- Thread starter rwood3444
- Start date
- Status
John120/240
Senior Member
- Location
- Olathe, Kansas
Drive a second ground rod. At least 6 ft from the first one.
- Location
- Connecticut
- Occupation
- Engineer
Where metal underground water pipe, metal structural frame and concrete-encased electrodes are not available, NEC 250.50 requires that one or more of the electrodes specified in 250.52(A)(4) thru (A)(8) be installed in used. This electrodes are ground rings, rod and pipe electrodes, other listed electrodes, plate electrodes and other local metal underground systems or structures.
I don't see where a secondary ground would be required by 250.50, unless your first ground is a single rod, pipe or plate with a resistance of more than 25 ohms to ground (250.56.) Then you could install another rod, pipe or plate, etc.
The description of what you have is not very clear. You talk about deriving a "secondary ground". I'm not sure what you mean by that. What do you have as a grounding electrode? If your only grounding electrode is a single ground rod, then unless you can show that it has a resistance to ground of 25 ohms or less, then 250.56 requires the addition of another electrode, usually another ground rod.
Is there not at least 20' of rebar in the footings? If so, then 250.50 and 250.52(3) require that it be used as a grounding electrode. If you have this, and other electrodes are not present, you don't have to add any. You don't even need one ground rod.
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