How do we know if my ground is good?

The most widely used specification is that of the NEC, which mandates for residential grounds a resistance of 25 or less. This is not a particularly difficult specification to meet. Others are more demanding, and may be specified by the engineer designing an electrical system, or by a client, or may come as part of the warranty requirements for advanced equipment.

The most commonly encountered specification for industrial grounds in general is 5 or less. Computers and process control equipment may demand as little as 1 or 2 .

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