Tommy Mac Discussions › Forums › Fix-it Forum: Home Improvement & Do It Yourself Repair Forum › Grounding a portable generator? › A few things. The power coming into your house is grounded › Grounding Electrodes › Not True › And By the Way
homebildThe NEC Code requires 25 OHM system grounding resistance.
The NEC Code does NOT prescribe just how that resistance should be achieved.
It could be from 2 grounding elctrode rods.
But it could also be from a single metallic water service pipe…
It could also be achieved via bonding/grounding to rebar in footings…but there is absolutely NO requirement for rebar to be placed in most residential footings anywhere in the US regardless of soil conditions.
The bottom line is that the Code is very broad and lenient in how one can achieve a 25 ohm resistance for grounding conductors and allows a multitude of methods to achieve the single 25 ohm end.
And none which are MANDATORY.