NI01 Telecommunications Bonding and Grounding - Commercial 2 Telecommunications Bonding and Grounding John French Technical System Engineer firstname.lastname@example.org 4/16/2015 Grounding and Bonding 101 What is Grounding and Bonding? A Grounding & Bonding System is most often associated with the protection of personnel, equipment and property from electrical disturbances caused by lightning, Electrostatic Discharge (ESD), surge or fault currents and transient voltages. Grounding and Bonding 101 What Does Grounding Do? • Provides a reference to earth to stabilize the system voltage for the Power Distribution System. • Provide paths for fault current to get back to its source without damaging equipment and facilitate operation of over current devices (breakers and fuses). • Promote equalization of electric potentials (voltages) between equipment, earth and personnel by bonding conductive paths together – Lightning – Electrostatic discharge SM What are the effects of Improper Grounding? Lower Reliability • An improperly designed grounding (and bonding) system may be a primary source of interference and emission. • According to the IEEE, the typical AC third-prong ground circuit is almost never sufficient to prevent damage to network equipment susceptible to ground-fault related potentials. • Poorly designed or improperly applied grounding, bonding, and shielding techniques often adversely affect the performance of electronic equipment – from the circuit board to the network system. • Approximately 70% of all anomalies, dysfunctions, or problems associated with power distribution systems are directly or indirectly related to bonding and grounding issues. SM Grounding and Bonding 101 The Risks of Improper Grounding & Bonding Safety Shocks Fire hazards Lightning Insurance data: $500 million/year due to lightning damage Equipment failure Industry experts estimate 27-33% of damaged equipment due to ESD (Electrostatic Discharge) The risk of electrical noise The performance of shielded data cable requires proper bonding & grounding. Understanding Grounding Systems To have a good conversation about Grounding Systems we need to establish a vocabulary to use to describe different areas of the system. We need to learn 3 terms: • Earthing • Grounding • Bonding SM Understanding Grounding Systems Understanding these three things will alleviate MOST grounding issues within any facility. Earthing SM Grounding Bonding Design is Critical A properly designed grounding and bonding system is: – Intentional, – Visually verifiable, – and Adequately Sized …to handle expected currents safely and without undue effect on susceptible electronic equipment. SM Integrated bonding and grounding enhances long-term equipment reliability and safety Data center SM Telecommunications room Entrance and direct burial How does telecommunications grounding and bonding work? • • Equalize potentials (voltages) by bonding conductive paths together – minimizes current flow SM Provide paths for current to get back to its source without damaging equipment Best Practice: Start at the Source and work your way down. MDC MDC Equipment Cabinet #1 Equipment Cabinet #2 Service Entrance SM • To prevent ground loops always route grounds down and out. • Never daisy chain. • Avoid multiple grounds. Facility Electrical Defining grounding and bonding NFPA 70-2011 (National Electrical Code, a.k.a. “NEC”) • Grounded (Grounding). Connected (connecting) to ground or to a conductive body that extends the ground connection. • Bonded (Bonding). Connected to establish electrical continuity and conductivity. SM Does the National Electrical Code require telecom grounding? 645.15 Grounding. All exposed non–current-carrying metal parts of an information technology system shall be bonded to the equipment grounding conductor in accordance with Article 250 or shall be double insulated…. Where signal reference structures are installed, they shall be bonded to the equipment grounding conductor provided for the information technology equipment. (NEC: NFPA 70-2011) SM Does the National Electrical Code specify an acceptable path for Fault Current? 250.5(4) Grounding and Bonding Electrical equipment, wiring, and other electrically conductive material likely to become energized shall be installed in a manner that creates a low impedance circuit from any point on the wiring system to the electrical supply source to facilitate the operation of overcurrent devices should a second ground fault from a different phase occur on the wiring system. The earth shall not be considered as an effective fault-current path. (NEC: NFPA 70-2011) SM Grounding Systems as Defined by BICSI The ITS designer must recognize that three separate and distinct grounding (earthing) systems should be in Place at every site. They are the: • ac grounding electrode system (e.g., in some countries it may also be known as the earthing system). • Equipment grounding system (e.g., in some countries it may also be known as the equipment bonding system). • Telecommunications bonding infrastructure. Because the purpose of each of these systems is unique, one cannot be used in place of the other two. Also, the installation requirements, improvement methods, and test methods of the three systems vary greatly. SM Grounding Systems as Defined by BICSI Equipment Grounding System Telecommunications Bonding Infrastructure Grounding Electrode System (GES) SM 18 Telecom Bonding Updates 4/16/2015 What is driving the need? (based on R&M Research) • Tolerance windows have shrunk as data rates have increased • Susceptibility to noise is higher for high speed Ethernet (1G, 10G) • Noise disturbances cannot be compensated by electronics • Good quality cable and properly engineered grounding and bonding system can help mitigate noise 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 Scope of TIA-607-B What is TIA-607-B? Distributors 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 Computer Rooms TGB TMGB TBB How does the telecommunications bonding system work? • Provide paths for current to get back to its source without damaging equipment – e.g. faults – Primary path for “dead metal” – Supplemental path for powered equipment • Promote equalization of electric potentials (voltages) by bonding conductive paths together – Lightning – Electrostatic discharge Implementation of a telecommunications grounding and bonding system TIA-607-B does not talk about ESD • Provide electrostatic discharge (ESD) protection • Bond the equipment to the racks/cabinets • Ensure that the racks/cabinets have electrical continuity • Bond the racks/cabinets back to the electrical panel • Bond nearby conductive items to the telecommunications grounding and bonding system 24 The 5 Steps document - GRFL02--SA-ENG ESD protection (best practice – not in TIA-607-B) • Manufacturers ESD resistance is designed to work under normal operational scenarios • All built-in ESD protection is worthless when the product is opened – must use external ESD protection • Service call – swap components VGA port USB/1394 ports Serial port Modem port Ethernet port Notebook: DC power input Desktop: AC power line DVI/HDMI port Source Littelfuse Example ESD protection wrist strap and docking options Panduit part RGESDWS Banana jack on ESD protection wrist strap fits ESD port provided on equipment (Cisco 6500 shown) Bent 45o port acts as a hook to hold wrist strap Equipment in cabinets and racks TIA-607-B: “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 Implementing the equipment grounding requirement Bond equipment with a jumper when possible Bonding cage nuts have teeth that cut paint when installed (CBN4K) 28 Bonding screws have threadforming threads and serrations under the head that remove the paint off mounting flanges and patch panels (RGTBSG-C) Some equipment isn’t designed for a supplemental bonding system • Can’t add a jumper • Can’t add a bonding screw or a bonding cage nut That’s OK. So long as the AC power system and the telecom bonding system are bonded together, no safety issues result Most servers cannot be grounded directly to the telecommunications grounding system Ground strip kits RGS Family • Ground strips have same xsectional area as #6 AWG wire • Strips also future-proof against a future installer bonding to the rack without thread-forming screws BICSI 002 will call for grounding strips or a grounding busbar in the cabinet. When the final standard is approved, the Grounding 5 Steps document will be updated to be consistent with the standard. Install the strip on the vertical rail and bond all other jumpers to it TIA-607-B requires racks and cabinets to be electrically continuous • Electrical continuity must be confirmed through the use of bonding jumpers, bonding hardware, or the removal of paint • Bonding jumpers must be a minimum of #12 AWG All Panduit racks and cabinets are electrically continuous, eliminating the need for jumpers Panduit telecom bonding products are not impacted by Cabinet 2.0 Integral bonding means that no additional jumpers are required to create electrical continuity within the rack or cabinet, which saves costs, speeds installation, and removes a variable that could otherwise cause problems later If the rack/cabinet is not electrically continuous, use a busbar • Bond busbar to rack/cabinets with thread-forming screws to create electrical continuity between the equipment mounting rails • Bond to busbar with 2-hole lug tongues for long-term connection reliability Threadforming screws 2-hole lug mounting New terminology introduced by TIA-607-B: Telecommunications Equipment Bonding Conductor (TEBC) Example TEBCs routed along auxiliary cable brackets (which help to maintain 50 mm separation) TEBCs TEBCs are bonded to the TGB • “The TEBC connects the TMGB/TGB to equipment racks/cabinets” • Minimum separation from power and telecom cables is 50 mm (2 in) Acceptable telecommunications equipment bonding conductor topologies for the telco closet, per TIA-607-B Rack bonding conductor (RBC) Telecommunications equipment bonding conductor (TEBC) Use two-hole lugs to bond to busbars and racks & cabinets. Compression is required on busbars Two hole compression lug One hole mechanical lug Connector considerations – TIA-607-B We will add this after we have finished characterizing the vibration and stress relaxation characteristics Mechanical connectors are allowed for bonding the TEBC/RGB to racks, but Panduit recommends compression to prevent loosening The intent of the standard is that only double set screw mechanicals can be used on racks. Not clearly stated in TIA-607-B 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 Building steel Conduits Cabling pathways (not shown) Information technology equipment (ITE) Racks and cabinets Supplemental bonding grid (SBG) Rack bonding conductor (RBC) Watch for this common problem Common Bonding Network Jumper Kit (RGCBNJ660P22) Specify who bonds the racks to the SBG! When you see a supplemental bonding grid (SBG) with nothing attached to it, the customer intended to have grounding but got nothing!!! Making this bond was in no one’s scope of work... (20% of the data centers have this problem) HTAP Crimping • HTCT HTAPs require 12 tons of compression • CT-2930/L is recommended • Can use other manufacturers’ tools and retain UL Listing/CSA Certification • Must use Panduit locator dies Patented locating rib guarantees fullwidth crimp 1st time, every time! CT-2930/L CD-930H-250 Locator Die HTCT HTAP Conductor sizing isn’t only about electrical issues… Standards call for a minimum #6 AWG for mechanical strength Size matters! Source: Picture from Internet Supplemental bonding grid construction per TIA-607-B Make aisle grounds convenient to racks and cabinets Cross aisle grounds at least every 10 feet (Unless column in way) •Use #6 AWG wire •Use pedestal grounding clamps at conductor intersections •1/0 bond to TGB • Bond to AC power ground through a local TGB When do we make an SBG on every-other-pedestal? • When we do not know where the racks and cabinets are going to go • When there is a stringerless access floor system (bonds each tile at one point) Example supplemental bonding grid GPQC family of access floor grounding (Mesh-BN) products • Up to two each of #6 AWG-2/0 conductors • Rated for fault current (not all commonly installed access floor connectors are) • Models for access floor pedestals from ¾” to 2” diameters Hinged U-bolt design allows for “no look” installation—saving 67% of installation time 44 Preventing loose busbar connections Two-hole compression lugs required on TGB & TMGB Telecommunications Grounding Busbar (TGB), BICSI/TIA-607 hole pattern (Type LCC-W) (Type GB2B, or Part GB2B0306TPI-1) BICSI-607 stainless steel TGB hardware stack-up (Parts HDW1/4-KT, HDW3/8-KT) Panduit tooling options CT-2930/L 14 ton battery tool for HTAP and lug connections CT-930 14 ton manual hydraulic tool for HTAP and lug connections CT-1700 controlledcycle tool for lug connections - or Panduit lugs can be crimped with select competitors’ tools and dies and still retain UL/CSA approvals and performance 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 (Panduit SBC & SBCT, respectively) #6 AWG conductor, green w/yellow jacket – OR – Specify systems that automatically bond to reduce chances of error PANDUIT® Wyr-Grid™ and GRIDRUNNER™ hardware automatically bonds sections, eliminating the need for jumper wires Armored fiber cables per TIA-607-B Armored fiber grounding cable clamp Cover protects clamp and provides neat appearance Mechanical clamp assembly • Mechanical clamp design is entirely external to armor—no risk of damage to fibers • Clamp assembly has more current-carrying capability than the armor it attaches to To grounding system Armored fiber optic cable Telecommunications Bonding Backbone (TBB) TBB and its bonds, adapted from Figure 32, TIA-607-B • 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 51 TIA-607-B TBB sizing 16mm2 400mm2 52 TIA-607-B-2 and the TBB… • Use of structural metal is permitted in lieu of a copper conductor for the TBB and GE (grounding equalizer, which connects TBBs to one another) • Bond to structural metal using a Listed connector (compression, mechanical, or weld) • Size bonding conductor according to rules in table in previous slide What metal qualifies? • Electrically continuous – 2-point measurements – Architectural drawings/asbuilts, when measurement not possible • Metal must be earthed (grounded) in at least one place Published August 21, 2013 53 Connectors for structural metal • Today: “GM” family of parts available for conductors from #4 AWG to 250 kcmil • Available around November: “GM” parts for conductors from #8 SOL to 1,000 kcmil Drill hole in structural metal, put stud through hole, fasten to structural metal surface with nut (provided) Insert wire you want to bond to structural metal here GUBC shown in product roadmaps today Grounding & Bonding Infrastructure The Grounding Electrode System – Connection to the Grounding Electrodes Article 250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes. “The grounding or bonding conductor shall be connected to the grounding electrode by exothermic welding, listed lugs, listed pressure connectors, listed clamps, or other listed means. “ Types of Connectors allowed by Code and Standards Mechanical Connections Compression Exothermic Welding Grounding and Bonding Systems Knowledge and Solutions for Multiple Applications Telecom Room Grounding Electrode System Telecommunications G&B Infrastructure Data Center Entrance Facility Control Panels Grounding and Bonding Systems Depth of Product Lines Terminals Power Connectors Data Center Kits Compression Taps Direct Burial CTAPF HTAP CTAP Mechanical Grounding Grounding and Bonding Systems Installation Tooling Grounding and Bonding Systems We Can Help Technical Support Design Consultation Product Selection Specification Template Tool Selection Knowledgeable Staff Product Literature White Papers Articles Part Drawings Questions? John French Technical System Engineer jrf@Panduit.com Thank You!
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