Handbook 44 – 2013 5.55. Timing Devices

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Table of Contents

Section 5.55. Timing Devices.............................................................................................. 5-35

A. Application .................................................................................................................................................. 5-35

A.1. General................................................................................................................................................5-35

A.2. Additional Code Requirements...........................................................................................................5-35

S. Specifications............................................................................................................................................... 5-35

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................5-35

S.1.1. Primary Elements..................................................................................................................5-35

S.1.2. Graduations...........................................................................................................................5-36

S.1.3. Indicators. .............................................................................................................................5-36

S.1.4. Printed Tickets. .....................................................................................................................5-36

S.2. Marking Requirements, Operating Instructions..................................................................................5-36

N. Notes............................................................................................................................................................. 5-36

N.1. Test Method. .......................................................................................................................................5-36

N.2. Broadcast Times and Frequencies.......................................................................................................5-37

T. Tolerances.................................................................................................................................................... 5-37

T.1. Tolerance Values. ...............................................................................................................................5-37

T.1.1. For Timing Devices Other Than Those Specified in T.1.2. For Time Clocks and Time 

Recorders and T.1.3. On Parking Meters..............................................................................5-37

T.1.2. For Time Clocks and Time Recorders. .................................................................................5-37

T.1.3. On Parking Meters. ...............................................................................................................5-37

T.2. Tests Involving Digital Indications or Representations. .....................................................................5-38

UR. User Requirements ..................................................................................................................................... 5-38

UR.1. Statement of Rates. .............................................................................................................................5-38

UR.2. Time Representations..........................................................................................................................5-38
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Handbook 44 – 2013 5.55. Timing Devices

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Section 5.55. Timing Devices

A. Application

A.1. General. – This code applies to devices used to measure time during which services are being dispensed 

(such as vehicle parking, laundry drying, and car washing).

A.2. Additional Code Requirements. – In addition to the requirements of this code, Timing Devices shall meet 

the requirements of Section 1.10. General Code.

S. Specifications

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A timing device shall be equipped with a primary indicating element, and may also 

be equipped with a primary recording element. A readily observable in-service light or other equally 

effective means that automatically indicates when laundry driers, vacuum cleaners, and car washes are in 

operation shall be deemed an appropriate primary indicating element.

(Amended 1979)

S.1.1.2. Units. – A timing device shall indicate and record, if the device is equipped to record, the time 

in terms of minutes for time intervals of 60 minutes or less and in hours and minutes for time intervals 

greater than 60 minutes.

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated time and recorded time, if 

the device is equipped to record, shall not exceed the equivalent of:

(a) one-half hour on parking meters indicating time in excess of two hours;

(b) six minutes on parking meters indicating time in excess of one but not greater than two hours; or

(c) five minutes on all other devices, except those equipped with an in-service light.

(Amended 1975)

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording 

elements shall be susceptible to advancement only during the mechanical operation of the device, except 

that clocks may be equipped to manually reset the time.

S.1.1.5. Operation of In-Service Indicator Light. – The in-service light indicator shall be operative 

only during the time the device is in operation.

S.1.1.6. Discontinuous Indicating Parking Meters. – An indication of the time purchased shall be 

provided at the time the meter is activated in units of no more than one minute for times less than one hour 

and not more than two minutes for times of one hour or more. Convenient means shall be provided to 

indicate to the purchaser the unexpired time.

(Added 1975) (Amended 1976)
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S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read.

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than 

the width of the minimum clear interval between graduations and the width of main graduations shall be 

not more than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less 

than 0.2 mm (0.008 in) in width.

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall be not less than 0.75 mm 

(0.03 in). If the graduations are not parallel, the measurement shall be made:

(a) along the line of relative movement between the graduations at the end of the indicator; or

(b) if the indicator is continuous, at the point of widest separation of the graduations.

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at 

least throughout that portion of its length associated with the graduations.

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, 

unless the indicator and the graduations are in the same plane, in which case the distance between the end 

of the indicator and the ends of the graduations, measured along the line of the graduations, shall be not 

more than 1.0 mm (0.04 in).

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with 

which it is used shall be not greater than:

(a) the width of the widest graduation; and

(b) the width of the minimum clear interval between the graduations.

S.1.3.4. Parallax. – Parallax effect shall be reduced to a practicable minimum.

S.1.4. Printed Tickets. – A printed ticket issued or stamped by a timing device shall have printed clearly 

thereon:

(a) the time and day when the service ends and the time and day when the service begins, except that a 

self-service money-operated device that clearly displays the time of day need not record the time and 

day when the service begins; or

(b) the time interval purchased, and the time and day that the service either begins or ends.

(Amended 1983)

S.2. Marking Requirements, Operating Instructions. – Operating instructions shall be clearly stated on the 

device.

N. Notes

N.1. Test Method. – A timing device shall be tested with a timepiece with an error of not greater than plus or 

minus 15 seconds per 24-hour period. In the test of timing devices with a nominal capacity of 1 hour or less, 

stopwatches with a minimum division of not greater than one-fifth second shall be used. In the test of timing 

devices with a nominal capacity of more than one hour, the value of the minimum division on the timepiece shall be 

not greater than one second. Time pieces and stopwatches shall be calibrated with standard time signals as 
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described in National Institute of Standards and Technology Special Publication 432, NIST Time and Frequency 

Dissemination Services, or any superseding publication.

(Amended 1978)

N.2. Broadcast Times and Frequencies. – Time and frequency standards are broadcast by the stations listed in 

Table N.2. Broadcast Times and Frequencies.

Table N.2.*

Broadcast Times and Frequencies

Station

Location,

Latitude,

Longitude

Frequency

(MHz)

Times of

Transmission

(UTC)

WWV

Fort Collins, Colorado

40Ε41' N

105Ε02' W

2.5

5.0

10.0

15.0

20.0

Continuous

WWVH

Kauai, Hawaii

21Ε59' N

159Ε46' W

2.5

5.0

10.0

15.0

Continuous

CHU

Ottawa, Canada

45Ε18' N

75Ε45' W

3.330

7.335

14.670

14.670

Continuous

*From NIST Special Publication 559, “Time and Frequency Users’ Manual,” 1990.

(Added 1988)

T. Tolerances

T.1. Tolerance Values. – Maintenance and acceptance tolerances for timing devices shall be as follows:

T.1.1. For Timing Devices Other Than Those Specified in T.1.2. For Time Clocks and Time Recorders 

and T.1.3. On Parking Meters. – The maintenance and acceptance tolerances shall be:

(a) On Overregistration: 5 seconds for any time interval of 1 minute or more; and

(Amended 1986)

(b) On Underregistration: 6 seconds per indicated minute.

(Amended 1975)

T.1.2. For Time Clocks and Time Recorders. – The maintenance and acceptance tolerances on overregistration and underregistration shall be three seconds per hour, but not to exceed one minute per day.

(Amended 1975)

T.1.3. On Parking Meters. – The maintenance and acceptance tolerances are shown in 

Table T.1.3. Maintenance and Acceptance Tolerances for Parking Meters.
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T.2. Tests Involving Digital Indications or Representations. – To the tolerances that would otherwise be 

applied, there shall be added an amount equal to one-half the minimum value that can be indicated or recorded.

UR. User Requirements

UR.1. Statement of Rates. – The price in terms of money per unit or units of time for the service dispensed and 

the number of coins the device will accept and be activated by at one time, shall be clearly, prominently, and 

conspicuously displayed.

(Amended 1976)

UR.2. Time Representations. – Any time representation shall be within plus or minus 2 minutes of the correct 

time in effect in the area, except on an individual clock used only for “time out”; in addition, the time indication of 

the “time-out” clock shall be the same as or less than that of the “time-in” clock.

(Amended 1975)

Table T.1.3.

Maintenance and Acceptance Tolerances for Parking Meters

Maintenance and Acceptance Tolerances

Nominal Time Capacity On Overregistration On Underregistration

30 minutes or less No tolerance 10 seconds per minute,

but not less than 2 minutes

Over 30 minutes to and 

including 1 hour No tolerance 5 minutes plus 4 secondsper minute over 30 minutes

Over 1 hour No tolerance 7 minutes plus 2 minutes

per hour over 1 hour