Power and Grounding

I just returned from 2004 Power Council, an invitation-only conference hosted by Thomas & Betts (www.tnb.com). About 90 persons from cable, telco, power, direct broadcast satellite (DBS) and regulatory agencies made the trip to Tampa, Fla., to attend. The conference focused on power and grounding, subjects that don’t always get much attention in today’s world of digital and other advanced technology. Given central Florida’s reputation as the country’s lightning capital, Tampa seemed an ideal venue. Presentations covered subjects including personnel, equipment and service hazards; bonding and grounding hardware corrosion; the first public peek at pending changes to the 2005 National Electrical Code®; the NEC development process and NEC Article 830; a luncheon keynote on cable network and drop inspections; headend grounding, bonding, line conditioning and backup power; home network grounding considerations; outside plant grounding and electrical protection; and SCTE activities in the standards arena. And all of that was on the first day! The second day’s presentations touched on infrared thermography; proper power cable sizing; circuit breakers and fuses; stationary battery hazards; central office grounding; and OSHA compliance. The take-aways from 2004 Power Council were safety-the people and equipment kind-and maintaining reliable service. What not to do Don’t get the idea that this conference was a yawner. After all, the subject matter is hardly at the top of the high-tech excitement list. But as I mentioned, the presentations were excellent. Some of the speakers added a little good-natured humor to what could have been an otherwise dry, but serious subject. For instance, Kramer.Firm’s Jonathan Kramer discussed system inspections of drop grounding and bonding, complete with several rather humorous real-world how-not-to-do-it pictures from some of his inspections (www.cabletv.com/pictures). Comcast’s Wayne Hall provided an informative overview of SCTE Working Group 7’s NEC program, then wrapped up his presentation with a slide-show explanation of where his accent comes from. Hall had attendees rolling on the floor laughing-you had to be there. I was honored to be among the speakers at 2004 Power Council, with a presentation titled "Headend Power’s Influence on Signal Integrity and Safety." The content covered facility exterior and interior grounding and bonding, line conditioning and backup power, all of which are especially critical in today’s headends. Why worry? The why behind the material in my presentation is straightforward: lightning; dirty power-voltage sags, transients, surges, harmonics and brief interruptions; and loss of commercial power. The negative consequences of these include personnel injury or death; latent equipment damage or outright failure; and degraded service availability. When you think about it, the why and the negative consequences apply to every part of a cable system: headend, distribution network and subscriber drops. Avoiding the negative consequences boils down to education, good practices, education, and follow-up quality control to make sure things are being done right. Oh, did I mention education? Look at Jonathan Kramer’s previously mentioned Web site if you need to be convinced that education is important. Grounding and bonding are something we tend to take for granted, and unfortunately they’re also topics that often get low priority. Cable’s not alone in this area. Comments from other conference attendees suggested that power, telco and DBS installation companies face these issues too. Education is what 2004 Power Council was all about. Lots of it squeezed into two days! OK, so where does one learn more? See the sidebar at right for a list of references I put together. What’s not included are applicable state or local codes, something with which you should be intimately familiar. Bookshelf bests If I had to pick my favorites, they would include the latest NEC, NESC, and if you can track down a copy, Motolora’s R56 manual. While not cable-specific, the 600+ page document includes a wealth of information and guidelines on telecommunications facility installation and protection. Polyphaser’s The ‘Grounds’ for Lightning and EMP Protection, Second Edition is quite good too. This year’s 2004 Power Council wasn’t the first of its kind. Thomas & Betts sponsored a Power & Grounding Council in 1996-also in Florida-and plan to host another one in two or three years. If you happen to be among the invitees, I encourage you to consider attending. You’ll be glad you did. Ron Hranac is a technical leader, Broadband Network Engineering for Cisco Systems, and senior technology editor for Communications Technology. Reach him at [email protected]. Did this article help you? Send comments to [email protected]. Power and Grounding References National Fire Protection Association (www.nfpa.org):

• NFPA 70-National Electrical Code®
• NFPA 75-Standard for the Protection of Information Technology Equipment
• NFPA 111-Standard on Stored Electrical Energy, Emergency and Standby Power Systems
• NFPA 780-Standard for the Installation of Lightning Protection Systems

American National Standards Institute (www.ansi.org):

• ANSI T1.313-2003-Electrical Protection for Telecommunications Central Offices and Similar Type Facilities
• ANSI J-STD-607-A-Commercial Building Grounding (Earthing) and Bonding Requirements for Telecommunications

Institute of Electrical and Electronics Engineers (www.ieee.org):

• National Electrical Safety Code� (IEEE)
• IEEE C62.41-1991-IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits
• IEEE 0081P-1983-Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Ground System (Part 1)

Underwriters Laboratories (www.ul.com):

• UL 467-Grounding and Bonding Equipment
• UL 497A-Secondary Protectors for Communication Circuits
• UL 497B-Protectors for Data Communication and Fire Alarm Circuits
• UL 1449-Transient Voltage Surge Suppressors

Other documents:

• Standards and Guidelines for Communications Sites-Motorola (www.motorola.com), document #68P81089E50-A (2000 edition of "R56" manual)
• The ‘Grounds’ for Lightning and EMP Protection, Second Edition-PolyPhaser Corp., 1993 (www.polyphaser.com)
• Outage Reduction-Cable Television Laboratories, 1992 (www.cablelabs.com)