9/10/2014

Telecommunications Grounding and Bonding Generic

ChandrashekarTechnical Manager (India & SW Asia)

Purpose and scope of TIA-607-B TIA-607-B grounding is normative and applies to entire building, not

just data center

TIA-607-B, “Generic Telecommunications

Bonding and Grounding (Earthing)

for Customer Premises”, is now

approved!

Scope now includes

grounding of ITE

What is TIA-607-B?Scope: Specifies requirements for a generic telecommunications bonding and grounding infrastructure, and its interconnection to other systems, for locations where telecommunications equipment will be or are installed

Major revision of J‐STD‐607‐A:• Includes G&B of telecommunications spaces (distributors and computer rooms)

• Continued harmonization efforts (as practicable) on terminology and practices with international standards

Scope of TIA‐607‐B

TBB

DistributorsDistributorsComputer Rooms

Computer Rooms

TGB TMGBTGB TMGB

Equipment in Cabinets and Racks

“Rather than relying on the ac power cord ground wire, it is desirable that equipment be

grounded in a verifiable manner as described in

this Standard.”

Figure 7—Example of three methods to bond equipment and racks to ground

TIA-607-B:

Telecommunications Bonding Backbone (TBB)

• Purpose of TBB is to reduce potential differences between interconnected telecommunications systems on different floors

• Originates at TMGB and extends throughout building using telecom pathways

• Connects TGBs that exist in each distributor

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TIA-607-B TBB sizing

Conductor sizing isn’t only about electrical issues…

Size matters!

Standards call for a minimum #6 AWG for mechanical strength

Source: Picture from Internet

Supplemental bonding grid construction per TIA-607-B

• #6 AWG round wire or 2” wide copper strips bonded at intersections

• Minimum grid density is 3 m (10 ft) centers

• Minimum 1/0 bond to TGB/TMGB

Example supplemental bonding grid

Example SBG construction

Make aisle grounds convenient to racks and cabinets

Cross aisle grounds every 10 feet

•Use #6 AWG wire•Use pedestal grounding clamps at conductor intersections• Bond to AC power ground through a local TGB

TEBC to rack connector – TIA-607-BOnly 2-hole mechanical is allowed for this application. Concerns:(1) Vibration test was done at one amplitude and

frequency, which is different from what data installations experience

(2) No consideration for temperature fluctuation(3) No consideration for stress relaxation

Mesh-BN: a collection of components (As per CENELEC documents, includes TIA-942’s Data Center Grounding Infrastructure as the “Supplemental Bonding Network” and IEEE Std 1100 calls the MCBN), per TIA-607-B

Information technology

equipment (ITE)

Racks and cabinets

Cabling pathways

(not shown)

Building steel

Supplemental bonding grid

(SBG)

Conduits

Rack bonding conductor (RBC)

Preventing loose busbar connections

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Two-hole compression lugs required

on TGB & TMGB

(Type LCC-W)

BICSI-607 stainless steel TGB hardware stack-up (requires locking washer, and

stainless or SiBr hardware)

(Parts HDW1/4-KT, HDW3/8-KT)

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BICSI Telecommunications Distributions Methods Manual (12th) on the TGB and TMGB

…The same considerations as are

found in TIA-607-B

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ANSI/NECA/BICSI-607-2011 busbars

Panduit recommendation on busbar hole patterns: pick a pattern and stick

with it. It’s confusing to have

multiple hole patterns later.

Recommend using the BICSI/TIA hole pattern, as it is well defined and known

in industry.

What else needs to be bonded?

• IEEE studies have indicated that the point of diminishing financial returns with respect to lightning strikes is 2 meters (6 feet)

• Bond anything that could become charged that a person could bump while working on a rack/cabinet for safety

• Therefore, bond any conductive path within six feet of your racks/cabinets

Bond cable tray and ladder rack sections

Split bolts – use tin plated if outdoors (SBC & SBCT,

respectively)

#6 AWG conductor, green w/yellow jacket

– OR –

Wyr-Grid and GRIDRUNNERhardware automatically bonds sections, eliminating the need for jumper wires

Specify systems that automatically bond to

reduce chances of error

Remote zone enclosures and TIA-607-B

TIA‐607‐B“Distributors” need TGB/TMGBReferences TIA‐568‐C.0 for definitionTIA‐568‐C.0, 4.4 Distributors“Distributors provide a location for administration, reconfiguration, connection of equipment, and for testing. Distributors can be configured as interconnections or cross‐connections…”Figure 3 of the same document shows distributors starting at “Active equipment”

My conclusion… If it has active equipment, then it needs grounding

Sizing the conductor•A TBB, per TIA‐607‐B, originates at the TMGB. It bonds TGBs to the TMGB (5.2.4)•A TEBC connects racks to the TMGB/TGB (7.1)•TGB is located “as close as practicable to the panelboard”•“The TEBC shall be a continuous copper conductor that is sized not less than a No. 6 AWG or as the largest size equipment grounding conductor in he ac branch power circuit(s) serving the racks/cabinet lineup.

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Panduit grounding research

• Panduit research over the last two years has found the presence of phase imbalance on the telecommunications grounding system in the steady‐state

• Frequencies are powerline and the first couple of harmonics

Observations:• High building steel currents•UPSs are at end of line-up creating power imbalance in the ground conductor•No noticed network degradation on the part of network operators

19Episodic/transient research

• 7 MHz transient measured on ACEG at CRAH, but not detectable at closest rack• Conclusion so far: mesh bonding and separate circuits from the AC panel are effective means of mitigating issues with transients

• Flat braids have not been shown to offer a tangible benefit for this application

Tektronix TPS 2024

CRAC PanelCRAC Panel

AH Systems BCP‐512 Probe AH Systems BCP‐512 Probe (high bandwidth)

Rack bonding conductor

Grounding rules of thumb for optimum surge suppression

“Optimum performance of surge protectors is achieved at five Ohms or below. Several manufacturers of electronic equipment also require five to ten Ohms as a maximum resistance for their gear to work correctly.”

‐ Ditek “Technical White Paper: Grounding 101”

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Two categories of facility:1. Minimum requirements: maintain 25Ω throughout year, recommends at least two electrodes

2. Enhanced requirements for critical facilities: designed to have 10Ω or less (and “preferably 5Ω or less”)

– Public safety facilities– Military installations– Data centers– Web hosting facilities– Central offices

“Where telecommunications equipment is distributed throughout a structure and may be interconnected by metallic links, the minimally required grounding system may not be adequate. Facilities with advanced requirements or distributed equipment will benefit from the addition of a building perimeter ground loop.”

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TIA-607-B-1 - External Grounding* TR 42.16 voted to adopt as normative on June 6, 2012

Design specifications, per TIA-607-B-1

• Commission a soil resistivity study– The most common method of measuring average soil resistivity is the four‐point method– Require a series of readings in different locations to get a better idea of the soil conditions

• Require measurements of the ground system resistance as verification of the design– 3‐pole fall‐of‐potential method (if room is available, and the ground is not connected to the

power system)– Clamp‐on meter

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TIA-607-B-1 potential equalization design highlights

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Summary