SECTION 26 05 27
TELECOMMUNICATIONS BONDING INFRASTRUCTURE
PART 1
1.01
1.02
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GENERAL
REQUIREMENTS
A.
The Division 27 Contractor shall work with the Division 26 Contractor who shall be
responsible for the grounding system and shall follow Section 26 05 26, "Grounding &
Bonding" requirements and include the telecommunications grounding listed in Section
1.02.B.1, below. The Division 27 Contractor shall be responsible for grounding work
identified in Section 1.02.B.2 below.
B.
The Contractor shall supply a grounding system as shown on the Drawings, specified
herein and per ANSI/TIA-607-B Generic Telecommunications Grounding (Earthing) and
Bonding for Customer Premises.
SCOPE
A.
The aim of this document is to install a proper grounding system to achieve the following
needs:
1. Safety from electrical hazards
2. Reliable signal reference within the network
3. Satisfactory and/or enhanced electromagnetic performance of the network
B.
The "Grounding System" shall be a shared responsibility between the Division 26
(Electrical) Contractor and Division 27 (Low Voltage) Contractor. See attached schematic
diagram. The Division 27 Contractor shall be responsible for coordinating his/her work
with the Division 26 Contractor and the General Contractor.
1. The Division 26 Contractor shall supply and install the grounding system as specified
in Section 26 05 26, "Grounding & Bonding" and is also to include the following:
a. Provide the TMGB (Telecommunication Main Grounding Busbar) in the MTR
(Main Technology Room/Demarc room).
b. The TMGB shall be connected to an earth ground (ground loop surrounding the
building, if available) and the building steel.
c. Provide a TGB (Telecommunication Grounding Busbar) in each TR located
throughout the facility.
d. Each TGB shall be connected to building steel and the equipment ground terminal
of the nearest AC electrical panelboard serving the telecommunications equipment
in the TR.
e. Provide and connect the TBB (Telecommunications Bonding Backbone) from the
TMGB to all TGBs.
2. The Division 27 Contractor shall:
a. Connect via compression connectors all equipment, ladder rack, basket rack,
telecom racks, cabinets, conduits, sleeves, and other equipment, in each TR and/or
MTR, green insulated, stranded copper ground conductor to the TGB and/or
TMGB located in each TR and/or MTR. These bonding conductors shall minimum
conductor size #6 AWG, and sized at 2 kcmil per linear foot up to a maximum size
of 750 kcmil per the table below.
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26 05 27 - TELECOMMUNICATIONS BONDING INFRASTRUCTURE
Sizing of the Bonding Conductors
TBB Length in Linear Feet
TBB Size (AWG)
Less than 13
6
14-20
4
21-26
3
27-33
2
34-41
1
42-52
1/0
53-66
2/0
67-84
3/0
85-105
4/0
106-125
250 kcmil
126-150
300 kcmil
151-175
350 kcmil
176-250
500 kcmil
251-300
600 kcmil
Greater than 301
750 kcmil
C.
PART 2
2.01
2.02
The Division 27 Contractor shall work with and coordinate with the Division 26 Contractor
to ensure that all aspects of the grounding system are complete and operational.
PRODUCTS
BUSBAR
A.
The TMGB (Telecommunication Main Grounding Busbar) shall be solid copper grounding
busbar, 1/4 inch thick x 4 inches high x 12 inches (minimum) length, as required to be
supplied by the Division 26 Contractor.
B.
The TGB (Telecommunication Grounding Busbar) shall be solid copper grounding busbar,
1/4 inch thick x 2 inches high x 10 inches (minimum) length, as required to be supplied by
the Division 26 Contractor.
C.
The TMGB and TGB shall be drilled with holes per NEMA standard for attaching
compression fittings to be supplied by the Division 26 Contractor.
D.
Vertical grounding strip busbars shall be provided for all equipment racks. Vertical rack
busbars provide clean bond to any rack mounted equipment regardless of whether or not
equipment has an integrate grounding terminal. Vertical rack busbars shall be a minimum
45U with universal mounting hold pattern.
COPPER CABLE
A.
All wire used for telecommunications grounding purposes shall be identified with green
insulation. Non-insulated wire shall use green tape wrap at each termination point.
B.
If not shown on Drawings, Division 26 Contractor shall size grounding conductors to be
used for connecting the TGBs to the TMGB and the building steel.
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26 05 27 - TELECOMMUNICATIONS BONDING INFRASTRUCTURE
C.
Telecommunications Bonding Backbone (TBB) Conductors
1. The TBB is a conductor that is intended to equalize potentials between TRs on multiple
floors of a building with an ultimate connection to the TMGB.
2. The TBB shall be installed in conduit.
3. The TBB shall be bare or insulated copper, minimum conductor size #6 AWG, and
sized at 2 kcmil per linear foot up to a maximum size of 750 kcmil. These sizes are
based upon TBB length per ANSI/TIA-607-B recommendations. The Division 26
Contractor shall bring to the attention of the A/E anywhere the TBB sizing appears
insufficient per the Table below.
Sizing of the TBB
TBB Length in Linear Feet
TBB Size (AWG)
Less than 13
6
14-20
4
21-26
3
27-33
2
34-41
1
42-52
1/0
53-66
2/0
67-84
3/0
85-105
4/0
106-125
250 kcmil
126-150
300 kcmil
151-175
350 kcmil
176-250
500 kcmil
251-300
600 kcmil
Greater than 301
750 kcmil
15-089
D.
Grounding Equalizer (GE) Conductors
1. The GE is a conductor that is intended to equalize potentials between TRs on the same
floor.
2. The GE shall be installed in conduit.
3. Multi-story buildings with multiple risers (multiple TBBs) shall employ a GE between
vertical grounding backbones at the top floor of the building and minimally at every
third floor in between to the lowest floor level. The GE conductor shall be no smaller
than the largest sized TBB.
E.
Bonding Conductor for Telecommunications (BCT)
1. The BCT is a conductor that is intended to bond the TMGB to the AC grounding
(earthing) electrode system.
2. The BCT shall be installed in conduit.
3. The BCT conductor shall be no smaller than the largest sized TBB.
F.
Telecommunications Equipment Bonding Conductor (TEBC)
1. The TEBC is a conductor that intended to bond the equipment racks to the TGB or
TMGB.
2. Racks and cabinets shall have individual rack bonding conductors (RBC) bonding to
the TEBC.
3. In smaller TRs (3-5 racks), it is acceptable to have TEBCs that go directly from each
individual rack to the TGB.
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26 05 27 - TELECOMMUNICATIONS BONDING INFRASTRUCTURE
G.
PART 3
3.01
Alternating Current Equipment Ground (ACEG)
1. The ACEG is a conductor that intended to bond the nearest AC electrical panelboard
serving the telecommunications equipment in the TR to the TGB or TMGB.
EXECUTION
WORK TO BE DONE
A.
The Division 26 Contractor shall provide the TMGB and the TGB in each room requiring
grounding.
B.
The Division 26 Contractor shall provide all grounding cabling required connecting the
TMGB to earth and building steel and all cabling required connecting the TGBs to building
steel and to the TMGB.
C.
The Division 26 Contractor shall provide all GE conductors where required.
D.
The Division 27 Contractor shall provide and connect all grounding cables required in the
MTR and TR to properly ground all equipment to the TMGB and TGB.
E.
The completed installation (from TGB to TMGB to ground) shall be tested by the Division
26 Contractor and a record of test supplied to the Division 27 Contractor and the Engineer.
The Division 27 Contractor shall include these test results in the "Record and Information
Manual."
END OF SECTION
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