150-712-200-02
Installation
HRE-712 List 1 and List 2
July 26, 2000
13
G
ROUNDING
THE
HRE-712 L
IST
1
AND
L
IST
2
The HRE-712 List 1 and List 2 require a resistance of 25
Ω
or less to ground as measured with a Megger-type
ohmmeter.
Grounding the HRE-712 requires the use of the following equipment:
•
One bullet bond
•
One ground rod for pole mounted enclosures (may require more than one rod)
•
One Megger-type ohmmeter
•
A 24-inch, 6 AWG enclosure spaced jumper (shipped with the HRE-712)
To ground the HRE-712, refer to
and follow the steps below:
1
Bond the main cable shield through the splice case using bullet bond.
2
Use a Megger-type ohmmeter to measure the resistance between the enclosure ground and the ground
connection point in the manhole. The resistance must be 25
Ω
or less.
If the resistance is 25
Ω
or less, proceed to
.
If not, follow local practices to lower the resistance to ground to 25
Ω
or less before proceeding to
3
Use a 6 AWG cable to connect the enclosure ground lug to the ground connection in the manhole. Torque the
ground lug between 18 and 22 inch-pounds.
4
Use a 6 AWG cable to connect the main cable shield to the ground connection in the manhole.
5
Use a Megger-type ohmmeter to measure the main cable shield resistance to manhole ground. The resistance
must be 5
Ω
or less.
6
If the resistance requirement in
is not met, ground the main cable shield every 2,000 feet (610m).
Grounding the stub shield reduces the possibility of EMI interference and stub shield
corrosion. Both units are shipped with their stub shield connected to the enclosure
ground plane through the 8-mil aluminum, braded grounding strap (shown in
).
The stub shield may also be grounded to the shield of the main feeder cable. If this is
preferred the stub shield’s internal braded grounding strap should be opened to prevent
ground loops, which could cause service affecting noise interference. This braded
aluminum shield may also need to be temporarily removed from the enclosure ground lug
when troubleshooting ground faults. To do so, remove the screw that secures the braided
ground strap to the mounting bracket on the card cage.
The stub’s screen divider is an insulated floating divider separating the Group 1 and
Group 2 pairs from the Group 3 and Group 4 pairs. DO NOT GROUND THIS SCREEN
DIVIDER. Doing so could result in degraded performance.
Ground the HRE-712 before splicing the cable stub into the main cable. This grounding
method or an accepted local grounding method must be used at all times to safeguard
personnel.
If the HRE-712 is improperly grounded, the LPU surge arrestors will not work and the enclosure
will be unprotected.
