ARTICLE 250: Grounding & Bonding

Article 250, covers general requirements for grounding and bonding of electrical installations, and the specific requirements of...

1. Systems, circuits, and equipment required, permitted, or not permitted to be grounded 2. Circuit conductor to be grounded on grounded systems 3. Location of grounding connections 4. Types and sizes of grounding and bonding conductors and electrodes 5. Methods of grounding and bonding 6. Conditions under which guards, isolation, or insulation may be substituted for grounding

alterations to stop objectionable current...if the use of multiple grounding connections results in objectionable current and the requirement of 250.4(A)(5) or (B)(4) are met, then the following alterations can be permitted...

1. discontinue one or more but not all grounding connections 2. change the locations of the grounding connections 3. interupt the continuity of the conductor or conductive path causing the objectionable current 4. take other suitable remedial and approved actions

Bonding jumper, supply side

a conductor installaed on the supply side of a service or within a service equipment enclosure, or for a seperately derived system, that ensures that the required electrical conductivity between metal parts required to be electrically connected

Effective ground fault current path

electrical equipment and wiring and other electrically conductive materials likely to become energized shall be installed in a manner that creates a low impedance circuit facilitating the operation of the overcurrent device or ground detector for high impedance grounded systems. It shall be capable of safely carrying the maximum ground fault current likely to be imposed on it from any point on the wiring system where a ground fault may occur.

Path for fault current for ungrounded systems

electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a low impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a different phase occur on the wiring system.

Bonding of electrically conductive materials and other equipment for ungrounded systems

electrically conductive materials that are likely to become energized shall be connected together and to the supply system grounding equipment in a manner that creates a low impedance path for groundfault current that is capable of carrying the maximum fault current likely to be imposed on it

Grounding electrical equipment for ungrounded systems

non-current carrying conductive materials enclosing conductors or equipment, or forming part of such equipment, shall be connected to earth in a mannner that will limit the voltage imposed by lightning or unintentional contact with higher-voltage lines and limit the voltage to ground on these materials

Bonding of electrical equipment for ungrounded systems

non-current carrying conductive materials enclosing conductors or equipment, or forming part of such equipment, shall be connected together and to the supply system grounding equipment in a manner that creates a low impedance path for a ground fault current that is capable of carrying the maximum fault current likely to be imposed on it

Grounding of electrical equipment for grounded systems

normally non-current carrying conductive materials enclosing electrical conductors or equipment, or forming parts with such equipment, shall be connected to earth so as to limit the voltage to ground on these materials

Bonding of electrical equipment for grounded systems

normally non-current carrying conductive materials enclosing electrical conductors or equipment, or forming parts with such equipment, shall be connected together ant to the electrical supply source in a manner that establishes an effective ground fault current path.

Bonding of electrically conductive materials and other equipment for a grounded system

normally non-current carrying conductive materials that are likely to become energized shall be connected together and to the electrical supply source in a manner that establishes and effective ground fault current path.

Electrical system grounding for grounded systems

shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize voltage to earth under normal operation

additional grouding and bonding requirements are locted in..

table 250.3