BELL SYSTEM PRACTICES SECTION 030-125-501 AT & TCo Standard Issue 4, February 1979 BUILDING MASTER PRECISE SETTING

CONTENTS PAGE 2.02 Compare the master daily with one of the following references: 1. GENERAL

2. METHOD

Operating Company precise time announcement 1. GENERAL machine

1.01 This section covers the method of setting Boston 617 637-1234 Eastern Time all building time reference sources to precise time. Newark 201 936-8181 Eastern Time

1.02 This section is being reissued to change the -+New York 212 936-1616 Eastern Time +- reference telephone number for the precise time announcement machine in Chicago and New Wash., D.C. 202 844-1212 Eastern Time York. Revision arrows are used to indicate the change. This reissue does not affect the Equipment -+ Chicago 312 936-3636 Central Time +- Test List. Detroit 313 472-1212 Eastern Time 1.03 All building time reference sources, such as master clocks and customer call timing devices, U.S. Bureau of Standards must be accurate at all . Boulder, 303 499-7111 Greenwich 2. METHOD Colo. Mean Time

2.01 Designate one electric clock as a building master clock. Choose a clock with a sweep second hand and preferably one that is not affected by office routine emergency power transfers. Affix Note: Allowance must be made if your local a tag or plastic tape to the master clock stating: differs from the above time zones. Choose a time reference geographically close Caution: Reset per Section 030-125-501. to your office.

NOTICE Not for use or disclosure outside the Bell System except under written agreement

Printed in U.S.A. Page 1 to

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12

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030-125-501

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2.03 master

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precise precise

Page

2

SECTION