BELL SYSTEM PRACTICES SECTION 030-125-501 AT & TCo Standard Issue 4, February 1979 BUILDING MASTER CLOCKS PRECISE TIME SETTING
CONTENTS PAGE 2.02 Compare the master clock 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 times. 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: time zone 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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11:59
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(5)
(3)
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030-125-501
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time.
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With
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2.03 master
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Page
2
SECTION