Filter
Top Products
MERLIN LEGEND Communications System Release 7.0
Pocket Reference
555-670-116
Issue 1
April 1999
36
Power and Grounding
— A metallic underground water pipe must be supplemented by
the metal frame of the building, a concrete-encased ground,
or a ground ring.
— Other local metal underground systems or local underground
structures such as tanks and piping systems.
— Rod and pipe electrodes, a 5/8-inch (1.6-cm) solid rod or
3/4-inch (1.9-cm) conduit or pipe electrode driven to a
minimum depth of 8 feet (244 cm).
— Plate electrode, a minimum of 2 square feet (61 square cm)
of metallic surface exposed to the exterior soil.
— Concrete-encased ground, which must be an electrode,
consisting of one of the following:
— At least 20 feet (6.1 m) of one or more steel reinforcing
rods, each being at least 1/2-inch (1.27 cm) in diameter.
— 20 feet (6.1 m) of bare copper conductor not smaller than
#4 AWG, encased in 2 inches (5 cm) of concrete. This
electrode must be located within and near the bottom of a
concrete foundation or roofing that is in direct contact with
the earth.
— Ground ring, consisting of at least 20 feet (6.1 m) of bare
copper conductor not smaller than #2 AWG, encircling the
building. The ground ring must be in direct contact with the
earth and buried at least 2.5 feet (77 cm) below the earth’s
surface.
WARNING:
!
Do not use a metal underground gas piping system. This is a
safety risk.
For most power surges, the following standard grounding
requirements provide adequate lightning and surge protection:
— Properly wired/grounded/bonded outside line protectors
— Properly wired/grounded AC outlet
— Properly grounded single-point ground bar
— Properly wired connection between single-point ground and
power supplies
Additional Power Surge Protection
The 391C1, 391A3, 391A2, and 391A1 power supplies have built-in
AC line protection. This built-in protection handles almost all
situations.
Occasionally, additional protection may be needed if the customer is
located in a heavy lightning area. The following products are
available:
— The 147A protector provides AC surge protection for
In-Range Out-of-Building (IROB) extensions. This protector
can also provide surge protection for the 391A power supply
module in heavy lightning areas.