CenturyLink Technical Publication

1 CenturyLink Technical Publication grounding - Central Office and Remote Electronic Equipment Environments Copyright 1990, 1996, 1999, 2001, 2002, 2003, 2006, 2012, 2015 77355 Printed in Issue I All Rights Reserved July 2015 PUB 77355 Notice Issue I, July 2015 NOTICE This Publication presents CenturyLink s view of the generic requirements or guidelines that describe grounding methods for metallic frames and electrical power supplies associated with Central Office (CO) Switching Equipment, Remote Switch Units or Modules (RSV/RSV), Storage Program Control Switching Systems (SPECS) both analog and digital, or other telecommunications equipment that is installed within a building, normally referred to as a Central Office buildings or Remote Equipment Enclosures.

2 CenturyLink reserves the right to revise this document for any reason, including but not limited to, conformity with standards promulgated by various governmental or regulatory agencies; utilization of advances in the state of the Technical arts; or to reflect changes in the design of equipment, techniques, or procedures described or referred to herein. Liability to anyone arising out of use or reliance upon any information set forth herein is expressly disclaimed, and no representation or warranties, expressed or implied, are made with respect to the accuracy or utility of any information set forth herein. This document is not to be construed as a suggestion to any manufacturer to modify or change any of its products, nor does this Publication represent any commitment by CenturyLink to purchase any specific products.

3 Further, conformance to this Publication does not constitute a guarantee of a given supplier's equipment and/or its associated documentation. Ordering information for CenturyLink Technical Publications can be obtained from the Reference Section of this document. PUB 77355 Comments Issue I, July 2015 COMMENTS PLEASE TEAR OUT AND SEND YOUR COMMENTS/SUGGESTIONS TO: CenturyLink Local Network Power Tech Support 700 W. Mineral, Littleton, CO 80210 (303) 707-5699 fax: (303) 707-9041 Information from you helps us to improve our Publications. Please take a few moments to answer the following questions and return to the above address. Was this Publication valuable to you in determining our requirements?

4 YES NO Was the information accurate and up-to-date? YES NO Was the information easily understood? YES NO Were the contents logically sequenced? YES NO Were the printed pages legible? YES NO If you answered NO to any of the questions and/or if you have any other comments or suggestions, please explain: (Attach additional sheet, if necessary) Name Date Company Address Telephone Number Email _____ PUB 77355 Table Of Contents Issue I, July 2015 TOC i CONTENTS Chapter and Section Page 1. Introduction .. 1-1 General .. 1-1 Cross-Reference of Terminology .. 1- 1 2. General Requirements .. 2-1 Reasons for proper AC and DC grounding .

5 2-1 Personnel Safety .. 2-1 Equipment and Distribution Circuit Protection .. 2-1 Electrostatic Discharges (ESD) .. 2-1 Reliability .. 2-1 Equipment Operation .. 2-1 Noise Reduction .. 2-1 Minimizing grounding and Bonding Impedance .. 2-2 3. Building Ground Requirements .. 3-1 Ground Electrodes .. 3-1 Acceptable Methods .. 3-3 Ground Ring .. 3-3 Deep Driven Rod .. 3-5 Ground Grid or Array .. 3-7 Counterpoise .. 3-7 Well Casings .. 3-7 Deep Well Ground .. 3-8 Backfilled Wells .. 3- 8 Supplemental grounding Electrodes .. 3-8 Materials .. 3-10 Ground 3-10 Exterior Ground Wire .. 3-13 Interior Ground Wire.

6 3-15 Connectors .. 3-17 Connections .. 3-19 Main Site Ground Bus (OPGP, SPGP, or PANI MGB) .. 3-20 Identification of grounding Conductors .. 3-21 Design Parameters of Vertical Equalizer System .. 3-21 Design Parameters of Horizontal Equalizer System .. 3-22 CO GRD System Raceway Application .. 3-24 grounding and AC Feeds for Separate Buildings .. 3-25 Table Of Contents PUB 77355 Issue I, July 2015 TOC-ii CONTENTS (Continued) Chapter and Section Page 4. AC Service Distribution and Equipment Ground Requirements .. 4-1 AC Neutral Conductor .. 4-1 AC Service grounding of Separately Derived AC Systems .. 4-1 NEC Code Requirements.

7 4-3 AC Service grounding Electrode Conductor .. 4-6 AC Equipment Ground Conductor .. 4-8 CenturyLink AC Equipment Ground Requirements .. 4-10 AC Installation Requirements .. 4-11 Engine-Alternator Set(s) .. 4-11 grounding for AC Standby Plants .. 4-12 Ground Fault Detection/Protection .. 4-14 Busduct System .. 4-17 AC Power Distribution Service Cabinets .. 4-17 AC Equipment Ground Busbars .. 4-17 Raceways .. 4-18 Lighting Distribution Systems .. 4-18 Cord Connected AC Operated Equipment .. 4-23 Frame Base Appliance Outlets .. 4-26 Trolley Type Busduct .. 4-26 Armored Cable .. 4-27 5. Integrated Ground Systems.

8 5-1 Integrated Ground Plane .. 5-1 Buried Objects .. 5-1 Frame grounding Methods .. 5-1 Integrated Ground Plane Loads .. 5-2 Frame grounding and Return Bus Reference for DC Power Supplies .. 5-2 Loads Fed from the Principal DC Source .. 5-3 Loads Fed from Internal Power Sources .. 5-3 grounding for Separately Derived DC and AC Power Supplies .. 5-3 grounding Internal DC and AC Power Supplies .. 5-3 Two or More Power Sources .. 5-4 PUB 77355 Table Of Contents Issue I, July 2015 TOC iii CONTENTS (Continued) Chapter and Section Page Central Office (CO GRD) System .. 5-4 Design Parameters of a COGB .. 5-4 Equipment Frame grounding .

9 5-6 Equipment Frame Busbar Functions as a Combination Discharge-Framework Ground Busbar .. 5-8 Relay Rack "Frame Return" Ground Busbars .. 5-8 Distributing and Protector Frame Busbars .. 5-8 Collocated Local Exchange Carrier grounding .. 5-9 The grounding Feed for Caged Physical Collocation .. 5-9 Fence grounding for Caged Physical Collocation .. 5-10 Isolated Ground Planes in Caged Physical Collocation .. 5-11 grounding for Other Types of Collocation .. 5-15 6. Cable Entrance Facility (CEF).. 6- 1 Determining Exposure to Foreign Potentials .. 6- 1 Central Office Protection .. 6- 1 CEF Protection Measures (Bonding and grounding ).

10 6- 2 Alternative Arrangements for Bonding and grounding Optical Fiber Cables .. 6- 3 Location of the CEF .. 6- 4 Air Dryer grounding .. 6- 5 7. Radio Equipment Ground Systems and Rooftop Lightning Protection .. 7- 1 Driven Ground Electrodes For Radio/Sites .. 7- 1 Frame grounding Methods .. 7- 1 The Exterior Ring Ground System .. 7- 2 Rooftop-Mounted Ring Grounds .. 7- 3 Non-Metallic Antenna Structures .. 7- 9 Metal Monopole grounding .. 7-10 Waveguides and Transmission Lines .. 7- 10 Tower Warning Lights .. 7- 10 Metallic Feed Line Support Structure .. 7- 11 Table Of Contents PUB 77355 Issue I, July 2015 TOC-iv CONTENTS (Continued) Chapter and Section Page Waveguide Hatchplate Bonds.