Telecommunications Bonding and Grounding
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 5
to Rev 6
in Telecommunications Bonding and Grounding.
---
title: Telecommunications Bonding and Grounding
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## The telecommunications bonding and grounding system shall establish a single, low-impedance path interconnecting telecommunications equipment, racks, cabinets, cable shields, pathway metallic components, and protectors to the building grounding electrode system, so that fault current is cleared, surge energy is conducted to earth, and electronic equipment operates without ground-loop interference.
−## The telecommunications system shall be bonded to the building grounding electrode system at exactly one point — the Primary Bonding Busbar — so that the telecommunications and electrical systems share a common reference to earth and no objectionable potential difference can develop between them under normal or fault conditions. {note}
+## The telecommunications system shall be bonded to the building grounding electrode system at exactly one point — the Primary Bonding Busbar — so that the telecommunications and electrical systems share a common reference to earth and no objectionable potential difference can develop between them under normal or fault conditions.
## The building grounding electrode system itself is covered by [[sync/grounding-and-bonding]]; the scope of this standard begins at the bonding conductor from the building grounding electrode system to the Primary Bonding Busbar and extends to every telecommunications space, rack, and cabinet on the project. {note}
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## The telecommunications bonding network described by ANSI/TIA-607-E is a tree-topology, single-point-of-connection system rooted at the building grounding electrode system. {note}
+## The Primary Bonding Busbar is the root of the tree; the Telecommunications Bonding Backbone connects the PBB to each Secondary Bonding Busbar serving a telecommunications space on a different floor or remote area of the building, and within each space served by an SBB the equipment racks, cabinets, cable trays, and metallic pathways are bonded back to the SBB by Telecommunications Equipment Bonding Conductors and Rack Bonding Jumpers. {note}
+
+## The bonding network shall be installed as a hierarchical tree without loops.
+
```datasheet
label: Bonding Network Topology
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```
−## The Primary Bonding Busbar is the root of the tree; the Telecommunications Bonding Backbone connects the PBB to each Secondary Bonding Busbar serving a telecommunications space on a different floor or remote area of the building, and within each space served by an SBB the equipment racks, cabinets, cable trays, and metallic pathways are bonded back to the SBB by Telecommunications Equipment Bonding Conductors and Rack Bonding Jumpers. {note}
−
−## The bonding network shall be installed as a hierarchical tree without loops.
−
## Grounding Equalizer {toc}
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## Equipment racks and cabinets house active telecommunications equipment whose chassis and grounding terminals shall be bonded to the telecommunications bonding network.
−## Bonding the rack itself does not automatically bond the equipment inside; both the rack frame and each individual chassis shall be considered. {note}
+## Bonding the rack itself does not automatically bond the equipment inside; both the rack frame and each individual chassis shall be considered.
## Rack Bonding Busbar (RBB) {toc}
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### Many equipment racks and cabinets are painted or anodized, and paint and anodizing layers are electrically insulating. {note}
+### Bonding connections to painted or anodized rack surfaces shall use listed paint-piercing or star-washer terminations that make contact with the underlying conductive metal, or the paint and anodizing shall be removed at the connection point to expose bare metal.
+
```datasheet
label: Bonding Termination to Painted/Anodized Rack
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```
−### Bonding connections to painted or anodized rack surfaces shall use listed paint-piercing or star-washer terminations that make contact with the underlying conductive metal, or the paint and anodizing shall be removed at the connection point to expose bare metal.
−
### After connection, the cleaned area shall be sealed against corrosion with a listed compound.
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### The chassis bonding path for PoE-sourcing equipment carries this return current. {note}
+### The Contractor shall confirm that PoE switches are bonded to the RBB by the dedicated chassis bonding terminal where provided by the manufacturer, and that the bonding path back to the SBB is continuous and of low impedance.
+
```datasheet
label: PoE Switch Chassis Bonding
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```
−### The Contractor shall confirm that PoE switches are bonded to the RBB by the dedicated chassis bonding terminal where provided by the manufacturer, and that the bonding path back to the SBB is continuous and of low impedance.
−
### A loose or high-resistance bond on a PoE switch produces measurable potential differences across the bonded shield network and can damage attached devices. {note}
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### Optical fiber cable does not require bonding at the cable itself, because the fiber is dielectric. {note}
+### Where the optical fiber cable contains a metallic strength member, a metallic armor layer, or a metallic moisture barrier, those metallic components shall be bonded to the telecommunications bonding network at each end of the cable.
+
```datasheet
label: Optical Fiber Cable Metallic Component Bonding
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```
−### Where the optical fiber cable contains a metallic strength member, a metallic armor layer, or a metallic moisture barrier, those metallic components shall be bonded to the telecommunications bonding network at each end of the cable.
−
### Indoor armored fiber, indoor/outdoor armored fiber, and outside plant fiber with metallic components shall be bonded at the fiber distribution unit by means of the manufacturer-provided shield/armor bonding terminal.
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### The intent is that any potential rise on the outside-plant sheath — from a lightning strike, a power cross, or an induced surge — is delivered to the same earth reference as the building electrical and telecommunications systems, so no large potential difference develops across equipment connected to both systems. {note}
−# Materials {toc}
+# Bonding Conductors {toc}
−## Bonding Conductors {toc}
+## Bonding conductors used in the telecommunications bonding network shall be copper conforming to ASTM B3 and ASTM B8.
−### Bonding conductors used in the telecommunications bonding network shall be copper conforming to ASTM B3 and ASTM B8.
+## Insulated bonding conductors shall be 600V-rated building wire with green or green-with-yellow-stripe insulation.
−### Insulated bonding conductors shall be 600V-rated building wire with green or green-with-yellow-stripe insulation.
+## Bare bonding conductors shall be soft-drawn copper.
−### Bare bonding conductors shall be soft-drawn copper.
+# Busbars {toc}
−## Busbars {toc}
+## The PBB, SBB, and RBB shall be solid copper bus bar conforming to ASTM B187, predrilled by the manufacturer for two-hole NEMA-pattern compression-lug terminations.
−### The PBB, SBB, and RBB shall be solid copper bus bar conforming to ASTM B187, predrilled by the manufacturer for two-hole NEMA-pattern compression-lug terminations.
+## Electro-tin plating shall be provided where specified to reduce contact-surface oxidation.
−### Electro-tin plating shall be provided where specified to reduce contact-surface oxidation.
+# Lugs and Connectors {toc}
−## Lugs and Connectors {toc}
−
```datasheet
label: Termination Lug Type — Bonding Busbars
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```
−### All lugs used to terminate conductors on the PBB, SBB, and RBB shall be listed two-hole compression lugs sized for the conductor and the busbar hole pattern.
+## All lugs used to terminate conductors on the PBB, SBB, and RBB shall be listed two-hole compression lugs sized for the conductor and the busbar hole pattern.
−### Lugs shall be of copper or copper alloy compatible with the busbar material.
+## Lugs shall be of copper or copper alloy compatible with the busbar material.
−### Lugs shall be installed with the manufacturer's specified tool and die, and the die imprint shall be visible on the installed lug as evidence of proper crimp.
+## Lugs shall be installed with the manufacturer's specified tool and die, and the die imprint shall be visible on the installed lug as evidence of proper crimp.
−## Bonding Hardware {toc}
+# Bonding Hardware {toc}
−### All bolts, washers, and nuts used at bonding connections shall be of a material listed for the bonding application and compatible with the copper or tin-plated copper surfaces being joined.
+## All bolts, washers, and nuts used at bonding connections shall be of a material listed for the bonding application and compatible with the copper or tin-plated copper surfaces being joined.
−### Stainless steel hardware is the common standard. {note}
+## Stainless steel hardware is the common standard. {note}
−### Galvanized hardware in direct contact with copper bus bar in damp environments shall not be used.
+## Galvanized hardware in direct contact with copper bus bar in damp environments shall not be used.
# Connections and Terminations {toc}
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### ANSI/TIA-607-E does not impose a numerical resistance acceptance threshold by itself; the Contractor shall compare the measured value against the resistance computed from the as-installed TBB conductor size and length, and shall investigate any value significantly higher than the computed value, which indicates a poor termination, undersized conductor, or incorrect routing.
−### A value of 0.1 ohm is a common target for SBB-to-PBB resistance in moderately sized commercial buildings; data centers and projects with high-availability telecommunications systems typically require lower values. {note}
+### A value of 0.1 Ω is a common target for SBB-to-PBB resistance in moderately sized commercial buildings; data centers and projects with high-availability telecommunications systems typically require lower values. {note}
### The Engineer shall set the project value based on the served equipment.
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## Where the achieved SBB-to-PBB resistance is marginal relative to the acceptance criterion, the Engineer may require re-testing during the warranty period to confirm that the bonding network's integrity has not degraded.