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Illustrated Changes to the NEC, 2002 Edition - Part 1

Article 250


250.4 General Requirements for Grounding and Bonding

Section 250-2 in the 1999 NEC was revised and relocated to 250.4. It now reads:

To ensure a safe electrical system, the following requirements identify the purpose of grounding and bonding of electrical systems. The requirements contained in other sections of Article 250 must be followed so that the electrical system will be safe from dangerous voltage.
(A) Grounded Systems.
(1) Electrical System Grounding.

Grounded electrical systems (transformer, generators, etc) must be connected to earth for the purpose of limiting the voltage imposed by lightning, line surges, or unintentional contact with higher voltage lines, by shunting the energy to the earth. In addition, electrical systems (power supplies) are grounded to the earth for the purpose of stabilizing the voltage to earth during normal operation. Figure 250–3

Author’s Comment: An “electrical system” as used in this subsection refers to the “source” such as the transformer/generator.

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