ET1 Installation Standards.txt

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SOVT section 8

For most applications, ground rods of +++++ diameter, and length of +++++, are used where bedrock is beyond a depth of ++++++.

The metal framework of buildings may exhibit a resistance to earth of less than __ ohms, depending upon the size of the building, the type of footing, and the type of subsoil at a particular location.

Class A bond:

Class B bond

Class C bond

DC resistance across bonding and grounding junctions shall not exceed +++ ohms for electrical safety

RF impedance across bonding and grounding junctions shall not exceed ++ ohms at ++ megahertz (MHz)

The earth electrode subsystem rods are interconnected with No. +++ AWG, or larger, bare copper cable

Other structures located greater than ++++ feet, are provided with a separate earth electrode subsystem

If there is more than one earth electrode subsystem, they are interconnected with two bare No.__ AWG copper cables that use independent routes

Measure the resistance to earth every +++ months after the initial 12-month period of installation using the FALL-OF-POTENTIAL

METHOD

Determine if the resistance of the earth electrode subsystem to ground using the FALL-OF-POTENTIAL METHOD is less than

++ ohms

Determine if the wideband noise with respect to earth ground measures less than 100 mV p-p, with periodic noise burst not

exceeding+++ V p-p, and occasional bursts up to +++ V p-p or greater

Measure the resistance to earth of all equipment, structures, fences and gates that are required to be bonded to ground and meets requirements of being less than +++ ohms

MIL-STD-188-124B recommends that ++++ be installed on 120-volt, single-phase, 15- and 20-ampere receptacles of C-E facilities.

Generally, less than ___ A is acceptable within a facility fault protection subsystem.

An average lightning strike consists of about three strikes, with the first strike discharging an average of +++

Subsequent lightning strikes will discharge about ____ the current of each preceding lightning strike.

Five effects of lightning

Mechanical

Electrical

Conductor Impedance

Induced Voltage

For this reason, metal objects within +++ feet of lightning down conductors should be electrically bonded to the down

conductors.

The high voltage of a lightning strike may be high enough to cause a flashover to conducting objects located as

close as +++ inches away.

Roof and down conductors must be a separate ++++ AWG cable, continuous, un-spliced and installed in as straight a line as possible in order to provide a low-impedance path from the highest conductive surface (air terminal) to the main ground connection point

The tip of the air terminal should be at least +++ inches above the structure you are protecting.

If a building has a sloping roof then air terminal placement should be on the corners and edges where terminals that are:

Equal to or greater than 24 inches in height are spaced a maximum of 25 ft. apart

If a building has a pitched roof then air terminal placement should be within +++ feet of ridged ends

If a building has a flat roof then air terminal placement should be +++++++++++

Any critical stuctures within a ++:++ cone of protection do not require lightning protection.

Any non-critical structures within a ++:++ cone of protection do not require protection

The maximum DC resistance of a 75-foot or less copper-clad steel down conductor shall not be greater than +++++ ohms per 1000 ft.

The maximum DC resistance for a 75 foot or more, copper-clad steel down conductor shall not be greater than ++++ ohms per 1000 ft.

The conductivity of copper-clad steel shall not be less than ___ of a solid copper conductor with an equivalent cross-sectional area.

The bend radius of a down conductor should not be less than ++++ inches.

The angle of any down conductor bend shall not be less than ++++ degrees

An air terminal must have at least ++++ paths for discharging the lightning to ground

At least +++ down conductors shall be placed on any structure

On structures exceeding 250 ft. in perimeter, an additional down conductor is required for each additional +++ ft. of perimeter.

The ground rod shall be at least +++ feet long and +++ inch in diamete

Ground rods are constructed of:

The lightning protection subsystem should be inspected visually every +++ months and mechanically every +++ months per NETA guidelines.

The +++++++ ground configuration is preferred for Communications Electronics (C-E) facilities

Signal reference subsystem grounding configurations for all of the equipment in a facility falls into one of three grounding configurations:

Single-point ground configuration

Multi-point (or equipotential) ground configuration

The single point ground configuration is recommended for use in low frequency electronic systems up to approximately ++++kHz

++++++ ground configurations are extremely poor grounds at RF frequencies because the ground impedance varies with frequency

++++++++ ground configurations are not recommended for use in C-E facilities

The multi-point ground type of configuration is recommended for higher frequencies—+++ kHz and above

A typical equipotential ground plane installation will consist of +++ inch square metal pads located throughout the building, flush with the surface of the concrete floor.

If using insulated wires for a ground terminal connection, they must be at least +++ AWG. If +++ AWG is used, it must be less than +++ feet in length.

Which of the following materials should be NOT when grounding an electrode?