Building Principal Ground (Bpg) Checks - Nortel DMS-100 Series Maintenance Manual

4–2 Grounding system maintenance

4.3 Building principal ground (BPG) checks

The BPG is the main point within a building at which the ground reference
potential is established. The BPG is directly referenced to earth by such
means as water pipes and/or electrodes driven into the earth. See Table 1–1
for terms used by various operating companies to designate the BPG and
other grounding bars.
Perform the following checks:
1 Locate the BPG and verify its correct location on the floor plan. If the
2 Verify that all cables attached to the BPG are labeled. If any cables are
3 Verify the connections shown on the schematic diagram match the actual
4 Using the clamp-on ammeter, measure the current magnitude and
297-1001-350 Standard 02.02 August 1997
DANGER
Risk of electrocution / risk of service outage
Connections to the BPG must never be broken. Disconnecting
a grounding conductor from the BPG can cause electrocution
and a service outage. If a connection must be disassembled, an
appropriately-sized jumper must be installed from the cable end
to the ground bar BEFORE the connection is disassembled.
floor plan is incorrect, make a note that the floor plan needs to be
corrected.
unlabeled, do the following:
a. Write ID REQ on a blank label and fasten it to the unlabeled cable.
b. Make a note that unmarked cables on the BPG must be identified and
properly labeled.
connection on the bar. If there are connections on the bar that are not
shown on the schematic:
a. Write NOT ON SCHEMATIC on a blank label and fasten it to the
cable not shown on the schematic.
b. Make a note that a possible illegal connection has been made to the
BPG or the schematic needs correcting.
direction on each cable attached to the BPG. Compare the values with
those on the schematic. If any current value does not match the value
indicated on the schematic:
a. Write CURRENT OUT OF SPEC on a blank label and fasten it to
the cable where the incorrect current was read.
b. Make a note that a possible grounding fault or violation has been
made on the equipment attached to this cable, or that the schematic
needs to be corrected.