To: All At&T Installation Suppliers s2

AT&T ENGINEERING REQUIREMENT CHANGE NOTIFICATION - ATT-TP-76400-026

TO: ALL AT&T ENGINEERING SUPPLIERS Date: 09-03-08

EFFECTIVE DATE: 5 days from posted date or as per Supplier’s Contract

Submitter’s Name: Al Bergman

TP: TP76400 Subject: Fig. 12-5 Bus Bar Capacity Action: Add Modification: Delete:

Section: 12 Section Title: Power Systems

Subsection: 2 Section Title: Battery/Rectifier (AC/DC)

Subsection: 2. 4.1 Subsection Title: Cable and Bus Bars

Prior to Change:

2.4.1 Whether cables or bus bars are used, each type of conductor shall be sized per Figure 12-4

taken from ATT-TELCO-IS-790-100-656, “DC Power Distribution”, to prevent heating or

exceeding the voltage drop requirement.

Post Change:

2.4.1 Bus bars shall be sized per Figure 12-5 taken from ATT-TELCO-IS-790-100-656, “DC Power Distribution”, to prevent heating or exceeding the voltage drop requirement. Bus Bar ampacity listed in Figure 12-5 is based on the bus bar configured with an open space equal to the thickness of the bus bar between each bar in the assembly, and the orientation of the bus bar. The higher ampacity listed is associated with horizontal (length-wise) runs (edge facing the floor), and the lower ampacity is associated with vertical (length-wise) runs, bus bar assemblies with spacing less than the thickness of the bus bar, or orientation other than horizontal (length-wise). Bus Bar Voltage Drop 1-Way = resistance per foot @70C x amperes x feet.

Questions relative to this IRCN should be addressed to Lawrence Lyles at (404) 927-7722.

Lawrence Lyles

Lead Network Engineering Manager, NP&E

Enterprise Technology Support

Access the TP's on the Extranet Site https://ebiznet.sbc.com/sbcnebs

Concurred

Senior Engineering Manager-Network Quality, West Date: 08-28-08

(Tim Harper)

Senior Engineering Manager-Network Quality, Southwest Date: 08-29-09

(Crissy Holmes)

Senior Engineering Manager-Network Quality, Midwest Date: 08-27-08

(Charles Stahulak)

Senior Engineering Manager-Network Quality, Midwest Date: 08-28-08

(Ray Coates, Jr.)

Lead Network Engineering Mgr. - Common Systems Power Date: 08-26-08

(Al Bergman)

Release Approved

Lead Network Engineering Manager Date: 09-02-08

(Lawrence E. Lyles)

Page 1 of 1