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Underground Drop Installation
You will need to connect 3 wires to the NIB and protector: drop, ground and Cat 5. They run from an STB or
LB connector to the customer’s power panel. (STB and LB connectors are access fittings that protect wire and
allow it to be routed at a 90-degree angle.) If there is no ground wire, either the technician will need to install
it. If there is no access available or if the basement ceilings are drywalled, the owner or builder will have to
install a ground.
Whenever possible, the CO end of the drop cable should be bonded to the terminal ground.
To install an underground drop, follow these steps:
1. Bring the three wires up through the hole in the bottom of the NIB.
2. Attach the NIB straight and level to the siding. Stucco and brick siding will need special attachments.
3. Attach #6 AWG ground wire to the ground lug in the NIB.
4. Cut down the drop and attach the sheath bond to the sheath. (This will be demonstrated a little later in
this course.)
5. Attach the proper #10 AWG ground strap or the green wire from “Y Braid” found on pre assembled NIBs to
the sheath bond of the drop. This should be attached to one of the ground lugs in NIB
6. Make sure other end of “Y Braid” is attached to a ground lug on the NIB door.
7. Terminate drop pair to the “CO-IN” side of the Tii 356 protector.
8. Terminate the Cat5 pair to the “Cust” side of the Tii 356 protector.
9. If not already done by builder, use split bolt to connect #6 ground from NIB to customers #6 AWG ground
from power panel. Always verify.
10. Dress all wiring neatly and be aware of pinch point of door closing. Sometimes a loose fitting Ty-Wrap is
recommended to keep the wires in alignment.
Types of Underground drops
1. Direct buried underground
Direct buried drops are run from pedestals, pull boxes and from encapsulated splices. In direct buried
situations, care must be taken to ensure that 30 cm (12 inches) of bonded cable is in the NIB before the bond,
to allow for ground bumps and frost heaves, which potentially can pull off the ground connection at the NIB.
2. Conduit enclosed buried drop
Conduit enclosed underground drops run from pedestals and pull boxes. In pull box situations (in BC), the
splicer will splice the underground drop into a cable, close the splice, and leave a coil of underground drop
for the I&R technician to pull through the conduit to the NIB.
In conduit situations, for new houses you may just have an empty conduit and will have to pull in your own
drop at the time of installing. Sometimes the contractor will pre-pull the drop, but this is not always the case.
Once the drop is in place, you will have to bond and ground both ends and terminate at the pedestal and NIB.
3. Composite fiber drop
Composite fiber underground drop is a standard cat 5 grease filled drop, with bonding sheath, wrapped
together with a 4-fibre tube.
Bond the Cat 5 cable to ground as normal
Always leave at least 2 meters of the fiber tube coiled in the NIB (6 meters in the pedestal)
Always place a cap over the fiber tube before working on the cable
Always place a yellow fiber tag in the NIB when completing your work
Always follow safe fiber procedures, including:
Always wear safety glasses
Never touch the fibers with bare hands
Always contain fiber trimmings in a “sharps” container
