NEC 250

Grounding electrodes of bare or electrically conductive coated iron or steel plates shall be at least _____ in. thick.

1/4

One or more metal in-ground support structure(s) in direct contact with the earth vertically for _____ ft or more, with or without concrete encasement is permitted to be a grounding electrode in accordance with 250.52.

10

Each tap conductor to a common grounding electrode conductor for multiple separately derived systems shall be sized in accordance with _____, based on the derived ungrounded conductors of the separately derived system it serves.

250.66

A(An) _____ AWG or larger copper or aluminum grounding electrode conductor exposed to physical damage shall be protected in rigid metal conduit, IMC, Schedule 80 PVC conduit, reinforced thermosetting resin conduit Type XW (RTRC-XW), EMT, or cable armor.

6

Where a metal underground water pipe is used as a grounding electrode, the continuity of the grounding path or the bonding connection to interior piping shall not rely on _____ and similar equipment.

All of these: bonding jumpers/ water meters/ grounding clamps

Equipment grounding conductors, grounding electrode conductors, and bonding jumpers shall be connected by _____.

Any of these: listed pressure connectors/ terminal bars/exothermic welding

Where practicable, rod, pipe, and plate electrodes shall be installed _____.

Below permanent moisture level

Bare or covered aluminum or copper-clad aluminum grounding electrode conductors without an extruded polymeric covering shall not be installed where subject to corrosive conditions or be installed in direct contact with _____.

Concrete

The frame of a vehicle-mounted generator shall not be required to be connected to a(an) _____ if the generator only supplies equipment mounted on the vehicle or cord-and-plug-connected equipment, using receptacles mounted on the vehicle.

Grounding electrode

If a building or structure is supplied by a feeder from an outdoor separately derived system, a system bonding jumper at both the source and the first disconnecting means shall be permitted if doing so does not establish a(an) _____ path for the grounded conductor.

Parallel

A grounding electrode conductor shall be permitted to be run to any convenient grounding electrode available in the grounding electrode system where the other electrode(s), if any, is connected by bonding jumpers that are installed in accordance with 250.53(C).

True

A grounding electrode conductor, sized in accordance with 250.66, shall be used to connect the equipment grounding conductors, the service-equipment enclosures, and, where the system is grounded, the grounded service conductor to the grounding electrode(s).

True

A grounding electrode shall be required if a building or structure is supplied by a feeder.

True

Alternating-current systems of 50V to 1,000V that supply premises wiring systems shall be grounded where the system is three-phase, 4-wire, wye-connected, with the neutral conductor used as a circuit conductor.

True

Where more than one concrete-encased electrode is present at a building or structure, it shall be permitted to bond only one into the grounding electrode system.

True

If a building or structure is supplied by a service or feeder with _____ or more disconnecting means in separate enclosures, the grounding electrode connections shall be made in accordance with 250.64(D)(1), 250.64(D)(2), or 250.64(D)(3).

Two

For a separate building or structure supplied by a separately derived system when overcurrent protection is provided where the conductors originate, the supply conductors shall contain _____.

an equipment grounding conductor

Grounded electrical systems shall be connected to earth in a manner that will _____.

limit voltages due to lightning, line surges, or unintentional contact with higher-voltage lines and stabilize the voltage-to-ground during normal operation

Where an ac system operating at 1,000V or less is grounded at any point, a(an) _____ shall connect the grounded conductor(s) to each service disconnecting means enclosure.

main bonding jumper

Where the supply conductors are larger than 1,100 kcmil copper or 1,750 kcmil aluminum, the main bonding jumper shall have an area that is _____ the area of the largest phase conductor when of the same material.

not less than 12 1/2 percent of

For ungrounded systems, noncurrent-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected together and to the supply system grounded equipment in a manner that creates a low-impedance path for ground-fault current that is capable of carrying _____.

the maximum fault current likely to be imposed on it

Ungrounded alternating-current systems from 50V to less than 1,000V shall be legibly marked "Caution: Ungrounded System - Operating _____ Volts Between Conductors" at _____ of the system, with sufficient durability to withstand the environment involved

the source or the first disconnecting means

In grounded systems, normally noncurrent-carrying electrically conductive materials that are likely to become energized shall be connected _____ in a manner that establishes an effective ground-fault current path.

together and to the electrical supply source

Grounding electrode conductor taps from a separately derived system to a common grounding electrode conductor are permitted when a building or structure has multiple separately derived systems, provided that the taps terminate at the same point as the system bonding jumper.

True

When installing auxiliary electrodes, the earth shall not be used as an effective ground-fault current path.

True