Ground Resistance Measurement [250.53(A)(2), 2020 NEC]

[marktheunitedstatescitezen]

And can my grounding rod for my inverter be about 15-20 feet away using 4 AWG copper wire ?

[eliaschico]

for the sub panel what size to put, I am going to put a sub panel that is 150 ft. away.

[dominicdoesit_tv]

So should a mobile home have two grounding rods?

[RICARDO]

One big inspector confusion on this matter is, if you have a water pipe electrode on site, do you have to add one ground rod only? Or should you drive 2 ground rods?
From what I read in the NEC, the requirements for a supplemental electrode are, if in the premises you have a single rod, pipe, water service pipe or plate electrode and your resistance to earth on that electrode is higher than 25ohms

[izzyperez]

When installing two rods what’s the max distance from each other and is it wrong to drive them both on 45

[thomast]

If all you have is a multimeter, where do you attach the leads to test the resistance?

Edit: Nevermind. Just saw your answer to similar question below.

[shanec]

Is the utility service power already referenced to earth by grounding rod at the transformer/utility pole? I am just trying to understand if there is some other reference to earth besides the electrode that you are taking the measurement of current flowing to earth. The reason I am asking is I am not 100% familiar with NEC and how the utility companies transformers are set up, but I am marine electrician and work on large ships that are normally I.T. type and what I have been taught is because the transformer is not tied to ground that when 1 of the 3 phase conductors suffers a earth fault no current will flow, no shut down of system only alarm in the insulation monitoring, however if a earth fault occurs on either of the other 2 conductors then there will be a fault current flow.

[TodKarlson]

Where is this 25 ohms being measured between? The ground conductor on one lead & just stab the dirt with the other lead?
Obviously the ground conductor to the ground rod would be about ZERO ohms, unless the acorn nut was detached or badly corroded.

[marktheunitedstatescitezen]

My house is already grounded, I’m adding a 5KVA Solar Inverter 230v Pure Sine Wave Inverter Charge Controller 48v at 5 KW is 86A x 1 Phase “ I drove a 7/8” Zinc Plated Ground Rod in Straight Down with 1 of those construction driving hammers a 8 Foot Ground Rod I hit Bedrock with 22” of the Ground Rod out of the ground 22” out of 8 Feet = 8x12”= 96”s Rod with 74”in the Ground it will not go deeper ! I had a hose flooding it w/ H2O & I’m 265 LBS with my weight on it ! Will not move ! “ is that good enough 74” inch’s underground ?

[prestonlatham]

The mobile home comment was irrelevant to the lesson and the other guy needs an ohmmeter, Mike you need a new panel these guys are chirping just to hear themselves talk and it’s interfering at least.