Earth ground resistance.
There is not one standard ground resistance
threshold that is recognized by all agencies.
However, the NFPA and IEEE have recommended
a ground resistance value of 5.0 ohms
or less.
The NEC has stated to "Make sure that system
impedance to ground is less than 25 ohms
specified in NEC 250.56. In facilities with sensitive
equipment it should be 5.0 ohms or less."
The Telecommunications industry has
often used 5.0 ohms or less as their value for
grounding and bonding.
The goal in ground resistance is to achieve
the lowest ground resistance value possible
that makes sense economically and physically.
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Reverse resistance should be infinite.
The maximum resistance across a switch should be infinite.
H
Insulation resistance.
YOU DO NOT "measure resistance on house current".You never measure resistance of anything that has any path to any source ofpower ... not to a wall outlet, a battery, a windmill, a solar panel, etc. You onlymeasure resistance when all power is REMOVED from the circuit or componentyou're measuring. Then, the range you choose for the ohmmeter depends onthe component or circuit you're measuring, NOT on how it's powered when it'sturned on.