607.htm

ANSI/TIA/EIA 607

Commercial Building Grounding and Bonding Requirements for Telecommunications

OVERVIEW OF THE TELECOMMUNICATIONS GROUNDING AND BONDING INFRASTRUCTURE

The electrical service entrance is outside the scope of this Standard and is grounded and bonded in accordance with all applicable electrical codes.

In all cases the applicable electrical codes for bonding and grounding for
telecommunications shall be met.

The telecommunications grounding and bonding infrastructure begins with a
connection to the service equipment (power) ground and extends throughout the building.

Although the electrical closet and associated panelboard(s) are not part of the
telecommunications infrastructure, they are referenced because they are integral to grounding and bonding.

COMPONENTS OF THE TELECOMMUNICATIONS GROUNDING AND BONDING
INFRASTRUCTURE

Major components of the grounding and bonding infrastructure are:

the identification elements
the bonding conductor for telecommunications
the Telecommunications Bonding Backbone (TBB)
the Telecommunications Main Grounding Busbar (TMGB)
the Telecommunications Grounding Busbar (TGB)
the Telecommunications Bonding Backbone Interconnecting Bonding Conductor (TBBIBC)

All bonding conductors shall:

be listed for the purpose intended and approved by a Nationally Recognized Testing Laboratory (NRTL).
be insulated and copper. The minimum bonding conductor size shall be a No. 6 AWG.
be bonded to each end of the conduit with a No. 6 AWG ground wire at a minimum if the conductors are inserted in a metallic conduit longer than 1 m (3ft)
be marked appropriately by a distinctive green color.

Labels, Color-Coding, and Markings

Labels shall:

be attached to each telecommunications bonding conductor
be located on conductors as close as practicable (ie., ease of access to read the label) to their point of termination
be nonmetallic. Refer to ANSI/TIA/EIA 606 for additional labeling requirements.

Bonding Conductors for Telecommunications

The bonding conductor for telecommunications shall:

bond the TMGB to the service equipment (power) ground
be, at a minimum, the same size as the TBB (see below)

The Telecommunications Bonding Backbone (TBB)

The TBB is a conductor:

that interconnects all TGBs with the TMGB
reduces or equalizes potential differences between telecommunications systems bonded to it.

A TBB is not intended to serve as the only conductor providing a ground fault current return path.

A TBB(s) originates at the TMGB, and connects to the TGB(s) in all telecommunications closets and equipment rooms.

A TBB design should take into account:

type of building construction, building size
the telecommunications requirements
the configuration of the telecommunications pathways and spaces.

the TBB shall:

be designed with over all design of the telecommunications backbone cabling system in mind
permit multiple TBBs as required
minimize the lengths of the TBBs
be an insulated copper conductor
have minimum conductor size of No. 6 AWG, and as large as No 3 AWG
be bonded together with a TBB interconnecting bonding conductor (TBBIBC) at the top floor and at a minimum of every third floor in between when two or more vertical TBBs are used in a multistory building
be connected to the TMGB

Water pipes shall not be used as a TBB.

Metallic cable shield shall not be used as a TBB in new installations.

Installation Considerations

TBB conductors:

shall be protected from physical and mechanical damage
should be installed without splices, where practicable.

If splices are required, they:

should be minimum and shall be accessible and located in telecommunications spaces
shall be connected using irreversible compression-type connectors, exothermicÂ welding, or equivalent
shall have joints adequately supported and protected from damage

The Telecommunications Main Grounding Busbar (TMGB)

The TMBG serves as:

the dedicated extension of the building grounding electrode system for the telecommunications infrasfructure
the central attachment point for telecommunications bonding backbones (TBB) and equipment, and is located such that it is accessible to telecommunicationsÂ personnel

The TMGB should:

be located in the telecommunications entrance room
minimize the bonding conductor length for telecommunications
serve telecommunications equipment that is located within the same room or space.

Extensions of the TMGB (i.e., other busbars) shall be telecommunications grounding busbars (TGB). Typically, there should be a single TMGB per building.

The TMGB shall:

be a predrilled copper busbar provided with standard NEMA bolt hole sizing and spacing for the type of connectors to be used
be sized with the immediate requirements and future growth in mind
have minimum dimensions of 6 mm thick x 100 mm wide and a length as required.

The TMGB should:

be electrotin plated for reduced contact resistance or if not plated, the busbar shall be cleaned prior to fastening of conductors.

Bonding to a Panelboard for Telecommunications

The TMGB shall:

be as close to the panelboard for telecommunications as is practicable
maintain clearances required by applicable electrical codes
have a panelboards Alternating Current Equipment Ground bus, or enclosure bonded to the TMGB
use listed 2-hole compression connectors, exothermic type welded connections, or equivalent for the bonding conductor connections
be bonded to all metallic raceways used for telecommunications cable within the same room or space
be insulated from its support (50mm is recommended)

The TMGB should:

be located to the side of the panelboard
be located vertically based on the entrance point of the cables (eg: overhead or from below)
use 2 hole compression connectors

The Telecommunications Grounding Busbar (TGB)

The (TGB) is the common connection point for telecommunications systems and equipment in the location served by that telecommunications closet or equipment room.

The TGB shall:

be a predrilled copper busbar provided with standard NEMA bolt hole sizing and spacing for the type of connectors to be used
have minimum dimensions of 6 mm thick x 50 mm wide and variable in length immediate requirement with consideration of future growth
be cleaned prior to fastening the conductors to the busbar
have TBBs and other TGBs within the same space bonded to the TGB
have the a continuous bonding conductor between the TBB and TGB routed in the shortest straight line path
have a panelboards Alternating Current Equipment Ground bus, or enclosure bonded to the TGB
maintain clearances required by applicable electrical codes
have the TGB shall be bonded to the TBBIBC as per 5.3.4.2 of the original standards documentation
be bonded to all metallic raceways used for telecommunications cable within the same room or space
use listed 2-hole compression connectors to connect the TBB to the TGB
be insulated from its support (50mm is recommended)

The TGB should:

be electrotin-plated for reduced contact resistance
bond the panelboard's ACEG or enclosure to the TGB if the TGB is not in the same space as the panelboard
be located to the side of the panelboard
be located vertically based on the entrance point of the cables (eg: overhead or from below)

Bonding to the Metal Frame

The metal frame of a building shall be bonded with a No. 6 AWG conductor to:

all TGBs where the metal frames are effectively grounded
the TGB where the metal frame is external to the room
the TMGB where the metal frame is external to the room

TGBs may be grounded to horizontal steel members in lieu of vertical members if, the horizontal members are permanently electrically bonded to the vertical members. B onding conductors and connectors for bonding the metal frame of a building shall be listed and approved for the purpose intended.

This Standard does not require the steel bars of a reinforced concrete building to be bonded to the TGB or TEF.

TELECOMMUNICATIONS ENTRANCE FACILITY

The TMBG:

should be located in the TEF
is the common point to which all grounding connections in a TEF are made
may serve as the TGB for collocated equipment in the TEF
should be located to facilitate the straightest route from the primary rotectors to the TMGB
shall be as close to the panelboard for telecommunications as practicable
shall be installed to maintain clearances required by applicable electrical codes

Location of the TMGB

primary protectors shall be separated by a minimum of 300mm (1ft) from any DC power, switchboard or high frequency cables even when these cable are contained in metallic or EMT conduit
the TMGB should be located near the backbone cabling and associated terminations
the TMGB should be located so that the bonding conductor for telecommunications is as short and straight as possible.

Other Attachments to the TMGB/TGB

The following elements shall be bonded to the TMGB/TGB

the shield or metallic member of a backbone cable
telecommunications primary protectors on the inter-building backbone cables
the pathway on the building side of an isolation gap in the telecommunications entrance facility

TELECOMMUNICATIONS ROOM and EQUIPMENT ROOM

The TGB shall:

be located in each telecommunications room and equipment room
be insulated from its support and separated by a minimum of 50mm
be located to provide the greatest flexibility and accessibility for telecommunications system grounding by minimizing lengths and number of bends of the bonding conductor to the TGB
be bonded together with all other TGBs in the same space

The TGB should:

be located near the backbone cabling and associated terminations if no panelboard has been installed in the telecommunications room
be located so that the grounding conductors are as short and straight as possible