Handbook 44 – 2022 5.55. Timing Devices

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Table of Contents

Page

Section 5.55. Timing Devices.................................................................................................. 5-41

A. Application .................................................................................................................................................. 5-41

A.1. General................................................................................................................................................5-41

A.2. Additional Code Requirements...........................................................................................................5-41

S. Specifications............................................................................................................................................... 5-41

S.1. Design of Indicating and Recording Elements and of Recorded Representations. .............................5-41

S.1.1. Primary Elements..................................................................................................................5-41

S.1.2. Graduations...........................................................................................................................5-42

S.1.3. Indicators. .............................................................................................................................5-42

S.1.4. Recorded Representations.....................................................................................................5-42

S.2. Marking Requirements, Operating Instructions..................................................................................5-43

S.3. Interference. ........................................................................................................................................5-43

S.4. Provisions for Sealing.........................................................................................................................5-43

S.5. Power Interruption. .............................................................................................................................5-43

S.5.1. Transaction Termination.......................................................................................................5-43

S.5.2. User Information...................................................................................................................5-44

N. Notes............................................................................................................................................................. 5-44

N.1. Test Method. .......................................................................................................................................5-44

N.2. Broadcast Times and Frequencies.......................................................................................................5-44

N.3. Interference Tests, EVSE....................................................................................................................5-44

T. Tolerances.................................................................................................................................................... 5-45

T.1. Tolerance Values. ...............................................................................................................................5-45

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..............................................................................5-45

T.1.2. For Time Clocks and Time Recorders. .................................................................................5-45

T.1.3. On Parking Meters and Other Timing Devices Used to Assess Charges for Parking...........5-45

T.2. Tests Involving Digital Indications or Representations. .....................................................................5-45

UR. User Requirements ..................................................................................................................................... 5-45

UR.1. Statement of Rates. .............................................................................................................................5-45

UR.2. Time Representations..........................................................................................................................5-46
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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). This code also applies to Electric Vehicle Supply Equipment 

(EVSE) when used to assess charges for time-based services in addition to those charged for electrical energy.

(Amended 2015)

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 timing device incorporated into an Electric Vehicle Supply 

Equipment system for use in assessing charges for timing separate from charges for electrical energy shall 

be equipped with the capability to provide a recorded representation of the transaction through a built-in or 

separate 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 and 2015)

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 following.

(a) For parking meters:

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

(2) six minutes on parking meters indicating time in excess of one but not greater than two hours.

(b) For an EVSE equipped with an integral time-based feature:

(1) one minute on an EVSE indicating time not greater than or equal to 60 minutes; or

(2) hours and minutes on an EVSE indicating time intervals in excess of 60 minutes.

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

(Amended 1975 and 2021)

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.
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S.1.1.5. Operation of In-Service Indicator Light. – For devices equipped with an in-service indicator 

light, the indicator shall be operative only during the time the device is in operation.

(Amended 2015)

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)

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. Recorded Representations.

S.1.4.1. Recorded Representations, Electric Vehicle Supply Equipment (EVSE) Timing Devices. – A 

timing device incorporated into an EVSE for use in assessing charges for timing separate from charges for 

electrical energy shall issue a recorded representation itemizing the charges for these services as defined in 

Section 3.40. Electric Vehicle Fueling Systems.

(Added 2015)
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S.1.4.1.1. Duplicate Receipts. – Duplicate receipts are permissible, provided the word “duplicate” 

or “copy” is included on the receipt.

(Added 2015)

S.1.4.2. Recorded Representations, All Other Timing Devices. – 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.

(Added 2015)

(Amended 1983 and 2015)

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

device.

S.3. Interference. – The design of the EVSE shall be such that there will be no interference between the time and 

electrical energy measurement elements of the system.

(Added 2015)

S.4. Provisions for Sealing. – For devices and systems in which the configuration or calibration parameters can be 

changed by use of a removable digital storage device, security shall be provided for those parameters as specified in 

G-S.8.2. Devices and Systems Adjusted Using Removable Digital Storage Devices. For parameters adjusted using 

other means adequate provisions shall be made to provide security for the timing element.

(Added 2015) (Amended 2019)

S.5. Power Interruption. – In the event of a power loss, the information needed to complete any transaction 

(i.e., delivery is complete and payment is settled) in progress at the time of the power loss (such as the quantity and 

unit price, or sales price) shall be determinable through one of the means listed below or the transaction shall be 

terminated without any charge for the electrical energy transfer to the vehicle:

(a) at the EVSE;

(b) at the console, if the console is accessible to the customer;

(c) via on site Internet access; or

(d) through toll-free phone access.

For EVSEs in parking areas where vehicles are commonly left for extended periods, the information needed to 

complete any transaction in progress at the time of the power loss shall be determinable through one of the above 

means for at least eight hours.

(Added 2015)

S.5.1. Transaction Termination. – In the event of a power loss, either:

(a) the transaction shall terminate at the time of the power loss; or 

(b) the EVSE may continue charging without additional authorization if the EVSE is able to determine it is 

connected to the same vehicle before and after the supply power outage. 
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In either case, there must be a clear indication on the receipt provided to the customer of the interruption, including 

the date and time of the interruption along with other information required under S.1.4.2. Recorded

Representations, All Other Timing Devices.

(Added 2015)

S.5.2. User Information. – The EVSE memory, or equipment on the network supporting the EVSE, shall 

retain information on the quantity of time and the sales price totals during a power loss.

(Added 2015)

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 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

40E41' N

105E02' W

2.5

5.0

10.0

15.0

20.0

Continuous

WWVH

Kauai, Hawaii

21E59' N

159E46' W

2.5

5.0

10.0

15.0

Continuous

CHU

Ottawa, Canada

45E18' N

75E45' W

3.330

7.335

14.670

14.670

Continuous

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

(Added 1988)

N.3. Interference Tests, EVSE. – On an EVSE equipped with a timing device used to calculate time-based charges 

in addition to any charges assessed for electrical energy, a test shall be conducted to ensure that there is no interference 

between time and electrical energy measuring elements.

(Added 2015)
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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: five seconds for any time interval of one minute or more; and

(Amended 1986)

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

(Amended 1975 and 1986)

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 and Other Timing Devices Used to Assess Charges for Parking. – The 

maintenance and acceptance tolerances are shown in Table T.1.3. Maintenance and Acceptance Tolerances for 

Parking Meters and Other Timing Devices Used to Assess Charges For Parking.

(Amended 2015)

(Amended 2015)

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 following information shall be clearly, prominently, and conspicuously displayed: 

(a) the price in terms of money per unit or units of time for the service dispensed; and

(b) for a timing device other than an EVSE, the number of coins the device will accept and be activated by at 

one time.

(Amended 1976 and 2015)

Table T.1.3.

Maintenance and Acceptance Tolerances for Parking Meters and

Other Timing Devices Used to Assess Charges for Parking

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
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UR.2. Time Representations. – Any time representation shall be within plus or minus two 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)