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 1) Heading of the Part :  Standards of Service for Gas Utilities and Alternative Gas Suppliers  
 
2) Code Citation :  83 Ill. Adm. Code 501  
 
3) Section Numbers :  Adopted Actions : 
501.10     Amendment  
501.20     Amendment  
501.110    Amendment  
501.160    Amendment  
501.180    Amendment  
501.190    Amendment  
501.200    Amendment  
501.230    Amendment  
501.250    Amendment  
501.270    Amendment  
501.280    Amendmen t 
501.610    Amendment  
 
4) Statutory Authority :  Implementing and authorized by Sections 8 -301, 8 -302, 8 -501, 9 -
201, 10 -101, 10 -107, 19 -110(e)(3) and 19 -115(b)(1), (b)(4) and (b)(5) of the Public 
Utilities Act [220 ILCS 5/8 -301, 8 -302, 8 -501, 9 -201, 10 -101, 10-107, 19 -110(e)(3) and 
19-115(b)(1), (b)(4) a nd (b)(5)]  
 
5) Effective Date of Rule s:  December 29, 2016  
 
6) Does this rulemaking contain an automatic repeal date ?  No  
 
7) Does this rulemaking contain incorporations by reference ?  Yes  
 
8) A copy of the adopted rules, including any material incorporated by reference, is on file 
in the Commission 's Springfield office and is available for public inspection.  
 
9) Notice of Proposal p ublished in the Illinois Register :  40 Ill. Reg. 7246; May 13, 2016  
 
10) Has JCAR issued a Statement of Objection  to this rulemaking ?  No  
 
11) Differences between Proposal and Final Version :  No substantive changes have been 
made.  
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 12) Have all the changes agreed upon by the A gency and JCAR been made as indicated in t he 
agreement letter issued by JCAR ?  None were made.  
 
13) Does this rulemaking replace any emergency rule currently in effect ?  No  
 
14) Are there any rulemakings pending on this Part ?  No  
 
15) Summary and Purpose of Rulemaking :  The amendments adopted here  make a number of 
corrections to Part 501, which will apply beginning on January 1, 2017, taking the place 
of Part 500.  Among other things, the amendments correct cross -references within the 
rules and correct citations to materials incorporated by referen ce.  In addition, Section 
501.160(g) expands the roster of national measurement institutes that may serve as 
sources for calibration standards.  
 
16) Questions or requests for information about this adopted rulemaking shall be directed to : 
 
Brian W. Allen  
Office of General Counsel  
Illinois Commerce Commission  
527 East Capitol Avenue  
Springfield  IL  62701  
 
217/558-2387  
 
The full text of the Adopted Amendments begins on the next page : 
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 TITLE 83:  PUBLIC UTILITIES  
CHAPTER I:  ILLINOIS COMMERCE COMMISSION  
SUBCHAPTER d:  GAS UTILITIES  
 
PART 501 
STANDARDS OF SERVICE FOR GAS UTILITIES AND  
ALTERNATIVE GAS SUPPLIERS  
 
SUBPART A:  GENERAL  
 
Section  
501.5   Effectiveness of this Part  
501.10  Definitions  and Incorporations by Reference  
501.20  Application  
501.30  Exem ption or Modification  
501.40  Complaints  
501.50  Customer Call Centers  
 
SUBPART B:  NATURAL GAS MEASUREMENT REQUIREMENTS  
 
Section  
501.100 Application of Subpart B  
501.110 Location and Installation of Meters  
501.120 Meter and Equipment Handling Requirements  
501.130 Trained Personnel  
501.140 Compressibility and Supercompressibility  
501.150 Fixed Factor Delivery  
501.160 Testing Facilities and Equipment  
501.170 Meter Accuracy Requirements  
501.180 Diaphragm Meters  
501.190 Rotary Meters  
501.200 Turbine Meters  
501.210 Orifice Meters  
501.220 Multi -Path Ultrasonic Meters  
501.230 Coriolis Meters  
501.240 Other Meter Types  
501.250 Sample Testing of Diaphragm Meters  
501.260 Meter Tests Requested by the Customer  
501.270 Commission Referee Tests       ILLINOIS REGISTER             354 
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 501.280 Meter Tests Request ed by Natural Gas Suppliers  
501.290 Meter Installation Inspection  
501.300 Correctors  
501.310 Transmitters  
501.320 Gas Chromatograph  
 
SUBPART C:  CUSTOMER INFORMATION  
 
Section  
501.400 Corrections and Adjustments for Measurement Error  
501.410 Information to Customers  
501.420 Meter Reading  
 
SUBPART D:  GAS SERVICE STANDARDS  
 
Section  
501.500 Pressure Regulation  
501.510 Pressure Survey  
501.520 Interruptions of Service  
501.530 Heating Value  
501.540 Good Engineering Practice  
 
SUBPART E:  EXTENSION OF MAINS  
 
Sectio n 
501.600 Extension of Distribution Mains in Urban Areas  
501.610 Extension of Distribution Mains in Rural Areas  
 
AUTHORITY:  Implementing and authorized by Sections 8 -301, 8 -302, 8 -501, 9 -201, 10 -101, 
10-107, 19 -110(e)(3) and 19 -115(b)(1), (b)(4)  and (b)(5 ) of the Public Utilities Act [220 ILCS 
5/8-301, 8 -302, 8 -501, 9 -201, 10 -101, 10 -107, 19 -110(e)(3)  and 19-115(b)(1), (b)(4)  and (b)(5)].  
 
SOURCE:   Adopted at 39 Ill. Reg. 12494, effective August 25, 2015; amended at 41 Ill. Reg. 
351, effective December 29,  2016.  
 
SUBPART A:  GENERAL  
 
Section 50 1.10  Definitions  and Incorporations by Reference  
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 a) Definitions  
 
"Act" means the Public Utilities Act [220 ILCS 5].  
 
"AGA" means the American Gas Association.  
 
"Alternative Gas Supplier" has the same meaning as in Section 19 -105 of the Act .  
 
"ANSI" means the American National Standards Institute.  
 
"Answer Time" means a measurement from the point the customer dialed the last 
digit of the natural gas public utility's or alternative gas supplier's telephone 
number and  a natural gas public utility or alternative gas supplier representative or 
automated system is ready to render assistance or accept information to process 
calls.  
 
"Auxiliary Equipment" means an integral device attached directly or remotely to a 
gas meter.  The function of auxiliary equipment is to adjust gas meter usage 
measurements to account for changes in gas temperature or pressure.  
 
"Bell Prover" means a cylindrical metal tank open at the top and nearly filled with 
liquid, in which a smaller calibrated  cylindrical tank called the bell, open at the 
bottom and having a dome -shaped top, can be raised or lowered. As the operator 
raises (negative pressure) or lowers (positive pressure) the bell, the bell will 
displace a known volume of air.  
 
"British Thermal  Unit" or "BTU" means the quantity of heat required to raise the 
temperature of one pound of water o ne degree Fahrenheit from 58.5°F to 59.5° F 
under a standard pressure of 30 inches of mercury at 32°F, or 1054.804 Joules.  
 
"Complaint" means an objection made to a natural gas public utility or alternative 
gas supplier , by a customer or another entity , as to its charges, facilities  or service. 
Complaints include a customer or other entity identifying and asking a natural gas 
public utility or alternative gas supplier  to address or resolve a problem or 
concern  and shall not include contacts that are limited to inquiry or seeking 
information.  
 
"Compressibility" means a gas volume correction factor calculated by using the 
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 pressure. The compressibility correction factor compensates for the deviation of 
gases from the ideal g as laws with increased pressure  and with variations in 
temperature and gas composition. Compressibility is not to be confused with 
"supercompressibility" , which is also defined in this Section.  
 
"Coriolis Meter" means a gas meter that infers mass flow rate by measuring tube 
displacement resulting from the Coriolis effect.  
 
"Corrector" means a device that corrects uncorrected gas meter volume according 
to the gas laws (Boyle's Law, Charles'  Law, and Real Gas Law).  
 
"Commission" means the Illinois Commerce Commission.  
 
"Commission Referee Test" means the accuracy test of any g as meter made in the 
presence of one or more members of Commission Staff.  
 
"Cubic Foot" means the unit of volume for purposes of measurement at a base 
temperature of 60°F at a base pressure of 14.73 pounds per square inch absolute.  
 
"Custody Transfer Meter " means  the meter, auxiliary equipment  and tertiary 
equipment a utility uses to measure a customer's gas usage.  
 
"Diaphragm Meter" means a positive displacement, bellows -type gas meter that 
alternately fills and empties compartments of known volume and tot als the 
number of times the cycle occurs to determine the volume of gas passing through 
the meter.  
 
"Defective Meter" means a meter whose condition is impairing service to a 
customer or a meter that has failed the requirements of Sections 501.170, 501.180,  
501.190, 501.200, 501.210, 501.220 or 501.230 500.170, 500.180, 500 .190, 
500.200, 500.210, 500.220  or 500.230 . 
 
"Flow Computer" means a device that electronically converts signals from a gas 
measurement system to a useful form such as flow rate.  
 
"Fixed Fa ctor" means the use of a gas pressure regulator to control gas pressure 
within an allowable pressure band over the required flow rate range considering 
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 correction factor applied via an arithmetic application or special index to a 
customer's measured usage.  
 
"Master Bell" means a primary bell prover used as a reference standard for target 
proof correlations and bell prover interface recertification.  
 
"Measurement Error" means an er ror in the calculation of a customer's gas usage 
due to the inaccuracy or improper setup of a utility's meter or other equipment 
whose function directly or indirectly affects the utility's measurement of a 
customer's gas usage.  
 
"Meter Accuracy" means the overall performance of a particular meter in 
relationship to a known reference or portable standard.  
 
"Meter Soaking Room" means a room maintained at the same atmospheric 
conditions as the meter proving room. The purpose of a meter soaking room is to 
store  and acclimatize meters prior to testing to ensure meter testing accuracy that 
is not affected by temperature variations.  
 
"Multi -path Ultrasonic Meter" means a device that derives gas flow rate by 
measuring the transit times of high -frequency sound pulses. Sound pulses transit 
between pairs of transducers located on or in the gas pipe.  
 
"Natural Gas Supplier" means an alternative gas supplier or any other natural gas 
supplier providing the natural gas commodity to a customer under a gas utility 
tariff or rider.  
 
"Orifice Meter" means an inferential meter that consists of an orifice plate 
perpendicular to the gas flow in a pipe. When gas flows across the orifice, it 
creates a pressure differential. Transmitters and transducers measure the pressure 
differential, static pressure, and other variables to determine the flow rate. The 
flow rate is proportional to the square root of the differential pressure across the 
orifice plate.  
 
"Portable Standards" means instruments that utilities use in the field or th e meter 
shop to test the accuracy of auxiliary and tertiary equipment, transmitters, and 
other equipment associated with correcting a meter's output.  
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 "Proving Room" means a temperature -controlled room where the utility uses 
equipment to determine the accu racy of meters.  
 
"Rated Capacity " or "Badged Capacity " means the hourly gas throughput of a 
meter as defined by the meter manufacturer.  
 
"Reference Standards" means instruments that utilities use only for verifying the 
accuracy of portable standards, and w hose accuracy is traceable back to the 
national standard maintained by the National Institute of Standards and 
Technology (NIST) or its successor.  
 
"Rotary Meter" means a positive displacement meter that alternately fills and 
empties rotating compartments of known size and totals the number of times the 
cycle occurs to determine the volume of gas passing through the meter.  
 
"Service Applicant" means a person who applies for residential or non -residential 
utility service for a location where the utility has not yet installed the meter.  
 
"Small Commercial Customer" has the same meaning as in Section 19 -105 of the 
Act.  
 
"Sonic Nozzle Automatic Prover" means a device containing a parallel bank of 
sonic flow nozzles that it uses to determine actual gas volume pa ssed through a 
gas meter in order to determine the gas meter's accuracy.  
 
"Sub -metering" means the placement of a meter downstream of a custody transfer 
meter.  
 
"Supercompressibility" means a value used in some flow equations for differential 
pressures (fo r example, orifice metering). In general, the supercompressibility 
factor is equal to the square root of the quotient of gas compressibility at base 
conditions divided by the gas compressibility at flowing conditions. 
Supercompressibility is not to be conf used with " compressibility ". 
 
"Tertiary Equipment" means a device that electronically converts signals from a 
gas measurement system (meter or auxiliary equipment or both) to a useful form 
such as flow rate (for example, flow computers).  
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 "Therm" means a unit of measurement representing a quantity of heat equivalent 
to 100,000 BTUs  and expresses the energy content of natural gas.  
 
"Transducer" means a sensing element capable of transforming values of physical 
properties such as pressure or temperature into equivalent electrical signals.  
 
"Transmitter" means a device designed to enhance the transmission of 
information from a transducer to a flow computer by the addition of an electrical 
circuit that converts the transducer output to a sta ndard signal in analog, digital  or 
frequency form.  
 
"Turbine Meter" means an inferential meter that measures gas flow by counting 
the revolutions of a rotor with blades, which turn in proportion to the gas flow 
velocity.  
 
b) Incorporations by Reference.  The f ollowing materials are incorporated by 
reference as of the date stated and include no later editions or amendments.  
 
American Gas Association, 400 North Capitol Street, NW, Washington DC 20001  
 
AGA Report No. 3, Orifice Metering of Natural Gas − Part 2: 
Specification and Installation Requirements, XQ0002 (April 
2000) (January 1, 2000)  
 
AGA Report No. 7, Measurement of Natural Gas by Turbine Meter, 
XQ0601 (February 2006) XQ0604 (January 1, 2006)  
 
AGA Report No. 9, Measurement of Gas by Multipath Ultrasonic Meters, 
XQ0701 (April 1, 2007)  
 
AGA Report No. 11, Measurement of Natural Gas by Coriolis Meter, 
XQ1301 (February 1, 2013)  
 
AGA Gas Measurement Manuals – Part 15: Electronic Corrector, XQ9901 
(May 1999)  
 
AGA Gas Measurement Manuals – Part 8:  Electronic F low Computers 
and Transducers, Revised (1988), XQ8805 (May 1988)  
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 American National Standards Institute and American Society for Quality 
(American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, 
New York 10036)  
 
Sampling Procedures and Tables for Inspection by Attributes, ANSI/ASQ 
Z1.4-2008 (January 1, 2008)  
 
American National Standards Institute and American Gas Association (American 
National Standards Institute, 25 West 43rd Street, 4th Floor, New York, New York 
10036)  
 
Diaphragm -Type Gas Displacement Meters (Under 500 Cubic Feet Per 
Hour Capacity), ANSI B109.1 -2000, AGA XQ0008 (June 2000)  
 
Diaphragm -Type Gas Displacement Meters (500 Cubic Feet Per Hour 
Capacity and Over), ANSI B109.2 -2000, AGA XQ0009 (June 2000)  
 
Rotary -Type Gas Di splacement Meters, ANSI B109. 3-2000, AGA 
XQ0010 (June 2000)  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501 .20  Application  
 
This Part sets forth minimum requirements and shall apply to any natural gas public utility as 
defined in Section 3 -105 of the Act and any alternative gas supplier as defined in Section 
501.10 500.10 . This Part shall not apply to any natural gas cooperative or to a municipal system 
when operating within its service territory. A public utility shall ret ain a record required by this 
Part for the period specified in 83 Ill. Adm. Code 510 unless this Part requires a longer retention 
period.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
SUBPART B:  NATURAL GAS MEASUREMENT REQUIREMENTS  
 
Section 501.110  Location and Installation of Meters  
 
a) A utility shall install a meter on a service applicant's premises as near as practical 
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 utilization area as mutually agreed upon by the utility and service applicant. The 
utility shall install a meter in a readily accessible location and protect the meter 
from corrosion and other damage.  
 
b) A utility shall not install a meter indoors unless outdoor installation is not p ossible 
or would make the meter installation financially infeasible. A utility shall not 
install an indoor a meter in sleeping rooms, in small, unventilated areas, or in 
locations where the installation, reading or removal of the meter may prove 
difficult or hazardous. A utility shall not install indoor meters less than three feet 
from any ignition source , air i ntake,  or source of heat that might damage the 
meter. A utility shall not install a meter in a location where expected temperatures 
are likely to exist outside the range recommended by the meter manufacturer.  
 
c) A utility shall not install a meter in fron t of a residential dwelling except with the 
consent of the service applicant or if no other practical external location is 
available.  
 
d) A utility shall install all meters in a secured upright and level position. A utility 
may vary from this requirement i f it installs a meter whose accuracy does not 
depend upon an upright and level installation. A utility shall install each meter to 
minimize anticipated stresses upon the connecting piping and the meter.  
 
e) If it is not practical for a utility to locate a meter installa tion in a place free of 
vehicular traffic hazards, the utility shall install meter protection such as guard 
posts or rails to protect the meter installation from damage. If the utility 
determines meter protection is necessary, then the utili ty shall inform the service 
applicant and include an estimate of the cost for the additional meter protection. 
The service applicant may install the guard posts or rails prior to the installation 
of the meter if the utility approves the proposed protection , or the service 
applicant may reimburse the utility for the cost and installation of the guard posts 
or rails.  
 
f) A utility may refuse to install a meter or to serve a service applicant if, in the 
utility's judgment, the metering installation is hazardou s or the service applicant's 
installation of piping or gas burning equipment is hazardous or of such character 
that the utility cannot provide service in a manner consistent with the 
requirements of Section 8 -101 of the Act.  In case of refusal, the utilit y shall 
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 and make the service applicant aware of the refusal to provide service within five 
business days after the decision to refuse service.  
 
g) A utility shall not insta ll a meter without a temperature compensation device 
unless the utility uses a corrector or other acceptable auxiliary equipment to 
correct the meter's reading for temperature variation. A utility may install 
non-temperature compensated meters in indoor lo cations if the utility uses only 
that type and size of meter in indoor locations.  
 
h) Each diaphragm, rotary  and turbine meter shall have a register or display on the 
meter or correcting device that displays consumption in a definite and known 
proportion t o the actual energy consumption of the customer, that is plainly 
visible, and that a customer can read. A customer may waive this requirement in 
writing. This requirement shall not affect the utility's right to secure meters for 
safety reasons or in situat ions in which the meter is subject to excessive risk of 
damage or tampering. At the customer's request, a utility shall explain to the 
customer how to read the meter used for billing that customer.  
 
i) A utility shall avoid installing a meter or auxiliary or tertiary equipment in 
locations where the meter or auxiliary or tertiary equipment is in direct contact 
with soil or concrete unless the manufacturer designed the meter or equipment for 
those conditions.  
 
j) A utility shall have security seals installed  on all meters and auxiliary and tertiary 
equipment or take measures to secure its equipment in order to deter unauthorized 
personnel from tampering with it.  
 
k) A utility shall secure all meter bypass valves when not in use in order to deter 
unauthorized personnel from tampering with them while also providing a readily 
apparent visual indication of tampering or other diversion activities.  
 
l) A utility shall secure a regulator that it uses in conjunction with fixed factor 
billing if it discovers tampering with the pressure setting.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.160  Testing Facilities and Equipment  
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 a) A utility shall provide laboratories, testing shops and other equipment, facilities  
and personnel as may be necessary to conduct the tests required by this Subpart or 
other orders of the Commission. A utility's laboratories, meter testing shops, and 
other equipment and facilities so provided shall be at all times available for 
inspection  by authorized representatives of the Commission.  
 
b) If a utility selects an agent to perform meter sample testing, meter accuracy tests 
when a meter is removed from service, and other requirements of this Subpart, or 
if a utility changes its agent, or if  the agent changes the location where it will 
conduct meter tests, the utility shall notify the Director of the Safety and 
Reliability  Division of the Commission in writing within 60 days after the 
selection or change. If an agent is selected or changed, t he utility shall provide the 
following information about the new agent:  
 
1) Name of agent;  
 
2) Name of contact for agent;  
 
3) Address and phone number of agent contact;  
 
4) Address of location where agent will conduct meter tests;  
 
5) Summary of meter type s and sizes that agent will test;  
 
6) Summary of services the agent will perform for the utility; and  
 
7) Identification of what changes, if any, caused the need for the notification.  
 
c) A utility shall provide meter testing equipment, including a bell pr over of not less 
than two -cubic -foot capacity. A utility shall maintain each of its active provers of 
all types in proper adjustment in order to determine the average accuracy of 
meters to within one -half of one percent. A utility shall provide suitable 
thermometers, pressure gauges, and temperature recorders and shall adequately 
control the temperature of the meter testing room, meter soaking room, and air 
supply used in testing meters to achieve the meter testing accuracy stated in this 
subsection . The te mperature of the meter testing and soaking room, when in use, 
shall not vary by more than 4 F during regular operating hours and shall not vary 
by more than 6 F throughout the year.  
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 d) In the event a meter shop experiences temperature variances that excee d those 
provided in subsection (c), a utility shall  immediately stop testing meters in the 
meter shop until the utility corrects the problem and the temperature returns to the 
normal levels for at least four continuous hours or the utility can demonstrate that 
the temperature variance between the meters and testing equipm ent is less than or 
equal to 1° F. 
 
e) A utility that uses a transfer prover to test the accuracy of meters in the field shall 
verify the transfer prover's accuracy by testing a reference me ter on the transfer 
prover at least every three months. If this testing shows a deviation of more than 
0.5% in the reference meter accuracy, the utility must take all necessary repairs or 
actions to bring the transfer prover's testing of the reference mete r to within 0.5% 
of the prior readings.  
 
f) An authorized representative of the Commission may check or establish the 
accuracy of all testing equipment used or intended for use in determining the 
accuracy of custody transfer meters, as well as the methods of operating that 
equipment. If a utility us es an agent to test the accuracy of its meters, the utility 
shall include provisions within its agreement with its agent for the authorized 
representatives of the Commission to conduct on -site audits of the agent's facility. 
An authorized representative of  the Commission shall perform an audit of the 
utility's testing equipment and methods at least every three years. The utility shall 
reimburse the Commission for all expenses related to audits of meter shops used 
or maintained by the utility or its agents l ocated outside of this State.  
 
g) A utility shall certify the accuracy of its testing equipment with measurement 
results that are traceable to the international system of units through at least one of 
the following national measurement institutes:  the Nat ional Institute of Standards 
and Technology for the United States, the National Physical Laboratory for the 
United Kingdom, the National Research Council for Canada, National 
Measurement Institute, American Association of Laboratory Accreditation, and 
the Physikalisch -Technische Bundesanstalt for Germany. against National Institute 
of Standards and Technology traceable standards.  Unless specified in this 
subsection (g) , the maximum certification interval is 36 months.  
 
1) A utility shall certify sonic nozzle  automatic provers at least every 12 
months. A utility shall also conduct the following maintenance at least 
every 12 months on sonic nozzle automatic provers:  
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 A) Inspect and clean nozzles and solenoids;  
 
B) Strap and recertify a master bell during the be ll interface 
recertification process;  
 
C) Recalibrate prover sensors and instrumentation in accordance with 
manufacturer's specifications;  
 
D) Test the function of the optical sensor; and  
 
E) Perform a complete bell interface certification followed by a 
reference meter target proof analysis.  
 
2) Utility verification checks on portable or reference equipment shall meet 
the following  requirements:  
 
A) A utility shall verify the accuracy of a portable standard against a 
reference standard at least every 12 mon ths. If the portable 
standard exhibits an error greater than 0.5%, the utility shall adjust 
the portable standard to read within 0.5% or replace the portable 
standard, or shall apply the proper correction factor.  
 
B) If a utility does not operate a referen ce standard, the utility shall 
certify or replace its portable standards at least every 12 months.  
 
C) A utility shall certify a reference standard at least every 36 months.  
 
D) A calibration certificate, verification certificate, or card signed or 
initialed by the person responsible for the calibration shall 
accompany a portable standard and a reference standard at all 
times. A utility, in lieu of maintaining the certificate or card with 
the device, may maintain the certificate or card in a central location 
or database that is available to Commission Staff upon request. A 
certificate or card shall provide the date and results of the last 
calibration or verification of the instrument. A utility , after each 
successive issuance of certificates or cards , shall keep any 
superseded certificates or cards on file for at least three years.  
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 h) A utility that tests meters with a rated capacity of 800 cubic feet per hour or less 
shall use one or more reference meters to conduct equipment checks every week. 
A uti lity shall designate and label reference meters for meter shop use only, and 
shall not adjust reference meters in any manner once in service unless they are in 
need of repair. A utility shall fully document all alterations to a repaired reference 
meter , including before and after accuracies. A reference meter shall carry a rating 
of 800 cubic feet per hour or less and shall have a similar size to the meters the 
utility tests. Every week during periods when a utility expects to test meters, a 
utility shal l test a reference meter on each prover that the utility uses to test meters 
of the reference meter's size. A utility shall record reference meter test results , 
including temperature , when testing on a sonic nozzle automatic prover, and shall 
record the te st results, temperature test flow times and bell pressure when testing 
on a bell prover. If the reference meter tests indicate an accuracy problem with 
any equipment, the utility shall cease using that equipment until the utility repairs 
the equipment.  
 
i) A utility shall allow meters tested within a meter testing facility to acclimate in 
the room containing the testing equipment or meter soaking room for at least 12 
hours prior to testing. This acclimation time is not required if the utility can show 
that it has taken sufficient actions to bring the meter temperature and the t esting 
equipment to within 1.0° F of each other.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.180  Diaphragm Meters  
 
a) A utility shall install a ne w diaphragm meter set and revisions to an existing 
diaphragm meter set in accordance with the recomme ndations of ANSI B109.1, 
XQ0008  (June 2000 ) for diaphragm meters with a rated capacity less than 500 
cubic feet per hour and in acco rdance with ANSI B109.2 , XQ0009  (June 2000 ) 
for diaphragm meters with a rated capacity of 500 cubic feet per hour or greater.  
 
b) A utility furnishing natural gas service with diaphragm meters shall ensure the use 
of suitable meter proving or testing equipment to determine the a ccuracy of the 
meter. The average accuracy of a diaphragm meter is determined by averaging the 
accuracy of the check and open flow rates.  
 
1) The open rate is 95% to 105% of the rated capacity.  
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 2) The check rate is 20% to 33% of the rated capacity.  
 
3) The maximum allowable accuracy spread between the open and check 
rates' accuracy is 1.0%.  
 
c) A utility shall conduct periodic accuracy tests on all installed diaphragm meters at 
least every 120 months unless the utility has provided notification to the 
Commission regarding its plans to conduct sample testing in accordance with 
Section 501.250 500.250 . 
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.190  Rotary Meters  
 
a) A utility shall install all rotary meters or revision s to existing rotary meter sets in 
accordance with the recomme ndations of ANSI B109.3, XQ0010  (June 2000 ). 
 
b) A utility furnishing gas service through a rotary meter shall verify that the meter's 
accuracy meets the requirements of Section 501.170(a) 500.17 0(a) before placing 
the meter in service.  
 
1) A utility may rely on the manufacturer's factory accuracy test to 
demonstrate that a new rotary meter meets the Section 
501.170(a) 500.170(a)  requirements only if the utility also conducts quality 
assurance revi ews on its new rotary meters.  
 
2) A utility that conducts quality assurance reviews must group the new 
meters into meter lots consisting of the same size and manufactured under 
the same conditions. The utility must then sample test these lots in 
accordance  with a single sample plan for normal inspection, Inspection 
Level II, of ANSI/ASQ Z1.4 -2008 using an acceptable quality level not to 
exceed 1.0%.  
 
3) In the event that a meter lot fails, the utility must either return the meters 
to the manufacturer or tes t all of the meters in the lot to verify compliance 
with Section 501.170(a) 500.170(a) . 
 
4) A utility shall retain a record of a meter's accuracy test for the life of the 
meter.       ILLINOIS REGISTER             368 
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c) A utility shall differential test an in -service rotary type positive displacement 
meter at least every 60 months. If the meter's pressure differential for a given flow 
rate is more than 50% higher than the utility's initial differential test or the factory 
published differential curve, a utility shall return the differentia l to a value below 
the 50% limit. If the utility cannot return the meter's differential to below the 50% 
limit, the utility shall clean and retest the rotary meter within 7 days and, if the 
meter's pressure differential is still more than 50% higher than t he utility's initial 
differential test or the factory published differential curve, the utility will replace 
the meter within 60 days. If the meter is of sufficient size that portions of a 
customer's structure require modification to remove the meter, then  the utility will 
replace the meter within 90 days unless the utility and customer agree to a longer 
period, not to exceed 180 days.  
 
d) If a utility documents conditions at the meter that prevent the utility from 
obtaining a differential reading from the meter, then the utility may delay 
verification until those conditions cease to exist or for four months, whichever is 
shorter. If a utility delays verification, it shall maintain for three years 
documentation of the conditions that prevented verification w ithin the required 60 
months and provide the documentation to an authorized representative of the 
Commission when requested.  
 
e) In lieu of the differential test requirement in subsection (c), a utility may conduct 
an accuracy test of a rotary meter. The a verage accuracy of a rotary meter is 
determined by averaging the accuracy of the check and open flow rates.  
 
1) The check rate is 10% to 33% of the meter's rated capacity.  
 
2) The open rate is 60% to 105% of the meter's rated capacity. The utility 
may subs titute the proving equipment's maximum capacity for the open 
flow rate if the meter's required testing volume exceeds the utility's testing 
equipment's capacity.  
 
f) A utility shall maintain the most recent 10 years of inspection records , as well as 
the da tes of all inspections of rotary meters.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.200  Turbine Meters       ILLINOIS REGISTER             369 
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a) A utility furnishing natural gas service with turbine meters shall install new 
turbine meters or revisions to  existing meter sets in accordance with the 
recommendations contained in AGA Report No. 7, Measurement of Natura l Gas 
by Turbine Meters, XQ0601  (February 2006 ). 
 
b) A utility shall accuracy test a turbine meter at least every 60 months.  
 
1) A utility shall  atmospherically test the accuracy of a turbine meter with an 
operating pressure not exceeding 25 psi at a minimum of four different 
flow rates of not less than 10% of meter capacity and not more than 105% 
of the meter capacity.  
 
2) A utility shall accuracy test turbine meters with an operating pressure 
exceeding 25 psi at the expected operating pressure of the meter 
installation using at least five flow rates of not less than 10% of meter 
capacity and no more than 105% of the meter c apacity. A utility may 
install a turbine meter at a location where the operating pressure falls 
within the range of 50% less than or two times greater than the pressure of 
the meter's accuracy test. For example, a turbine meter that was accuracy 
tested at 100 psi is acceptable for delivery pressures from 50 psi (50% of 
100) through 200 psi (2 x 100).  
 
3) A utility may accuracy test its turbine meters in natural gas or air. A utility 
that conducts accuracy tests with air shall account for the Reynolds 
number  equivalence as set forth in AGA Report No. 7, Measurement of 
Natural Gas by Tur bine Meters, Appendix E, XQ0601  (February 2006 ). 
 
4) When tested at the expected delivery pressure of the in -service location, a 
turbine meter shall demonstrate a tested accura cy within ±1.0% of the 
accuracy shown over the manufacturer's entire published flow range.  
 
c) A utility furnishing natural gas service with a dual rotor turbine meter that has an 
external means of verifying meter accuracy may extend the accuracy test 
requirement to at least every 120 months if the utility can demonstrate that it 
verifies the accuracy of the meter at least every six months and that the meter's 
performance meets the manufacturer's guidelines.  
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 d) A utility shall spin test and, if necessary, lubricate its turbine meters at least every 
12 months. If a turbine meter is not equipped with external lubrication provisions 
or external means of verifying the operation of the meter, a utility shall spin test 
the meter every six months. If the turbine m eter's spin time is not equal to or 
greater than the minimum spin time specified by the manufacturer, the utility shall 
make corrections to the meter to allow the spin time to equal or exceed the 
manufacturer's specifications.  
 
e) A utility is not required  to conduct a spin test of its dual rotor turbine meter if the 
utility furnishes natural gas service with a dual rotor turbine that has an external 
means of verifying rotor health, the utility can demonstrate that it verifies the 
health of the rotor at lea st every six months, and the utility can demonstrate the 
performance of the rotor meets the manufacturer's guidelines.  
 
f) A utility shall maintain the most recent five years of inspection records , as well as 
the dates of all inspections for the most recen t 10 years, except accuracy tests. A 
utility shall maintain documents for each turbine meter's most recent accuracy 
test, the prior accuracy test, and the dates of any other accuracy test that occurred 
during the prior 10 years.  
 
(Source:  Amended at 41 Il l. Reg. 351, effective December 29, 2016)  
 
Section 501.230  Coriolis Meters  
 
a) A utility shall install a Coriolis meter in accordance with the recommendations of 
AGA Report #11, Measurement of Natural Gas by Coriolis Meter, XQ1301 
(February 2013).  
 
b) A utility shall verify the proper operation of an installed Coriolis meter at least 
every 12 months by verifying that the meter meets the manufacturer's tolerances 
using, at a minimum, all of the following inspection requirements:  
 
1) Meter zero flow check;  
 
2) Meter sensor check; and  
 
3) Meter transmitter check.  
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 c) A utility shall calibrate a Coriolis meter at least every 120 months. However, if 
the utility can demonstrate that the meter meets the manufacturing tolerances set 
forth in Section 501.220(b) 500.220(b)  and the utility conducts an annual 
inspection of the meter body to ensure that the meter body has not incurred 
damage that would affect the meter's accuracy, the utility may forego the 120 -
month calibration requirement.  
 
d) When a utility remove s a Coriolis meter from service, the utility shall verify the 
meter's existing accuracy prior to altering the operation of the meter. This 
verification replaces the requirements of Section 501.170(d) 500.170(d)  for 
Coriolis meters.  
 
e) A utility shall maint ain the most recent five years of inspection records. A utility 
shall also maintain documents for each Coriolis meter's most recent accuracy test, 
the prior accuracy test, and the dates of any other accuracy test that occurred 
during the prior 10 years.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.250  Sample Testing of Diaphragm Meters  
 
a) A utility may, at its option and upon giving notice to the Commission, adopt 
scientific sample procedures for new and in -service dia phragm meters.  
 
b) A utility shall develop sample testing lots for new meters that consist of meters of 
a single type and size  that were  manufac tured under the same conditions  and at 
essentially the same time. All sample testing procedures shall be in acco rdance 
with Inspection Level II of ANSI/ASQ Z1.4 -2008.  
 
c) A utility shall establish meter sample testing lots for in -service meters that consist 
of meters of a similar type, size and year of installation or year of purchase. In the 
ninth and every subsequ ent year thereafter that the meters are in service, a utility 
shall test their accuracy in accordance with Inspection Level II of ANSI/ASQ 
Z1.4-2008.  
 
d) In order to comply with the accuracy limits of Section 501.170 500.170 , a utility's 
sample testing plan  for new meters shall provide an acceptable quality limit not to 
exceed 1.0% in order to assure a process average of at least 99%.  
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 e) A manufacturer shall test a new meter, and the resulting test record shall 
accompany the meter to retirement. A utility shall use the manufacturer's test as 
the initial test of the meter. However, if a utility tested the new meter prior to 
placing it into service, then the utility shall use its test as the meter's initial test.  
 
f) A utility's sample testing plan for meters  in service shall provide an acceptable 
quality limit of 6.5% in order to assure a process average of at least 93.5%. A 
meter is deviant if the average of its check -rate and capacity -rate accuracy test 
results in accuracy more than 3.0% fast or 3.0% slow. A utility must complete all 
sample tests by the end of the calendar year in which the tests are due for 
completion.  
 
g) If a utility determines that a meter lot has failed sample testing, the utility shall 
remove all remaining meters in the failed lot from  service within 24 months after 
completion of the current year's sampling.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
Section 501.270  Commission Referee Tests  
 
a) Subject to the provisions of subsection (b), a customer may not r equest a referee 
test of a meter used to measure the customer's gas consumption if the utility that 
provides service to the customer does not have the necessary testing equipment.  
 
b) If a customer requests a referee test of the meter used to measure the c ustomer's 
gas consumption, but the utility's testing facility is located out of state, the utility 
shall provide the option of having the meter tested at an in -state testing facility, 
provided the alternative location is in good standing with the Commissio n and the 
location is capable of testing the meter. A meter shop is in good standing if a 
Commission representative has conducted a review of the facility for compliance 
with the requirements of this Part within the last 40 months and the meter shop 
has no  outstanding non -compliance issues associated with its ability to accurately 
measure meter accuracy. A Commission representative shall advise , upon request 
of a utility , if a meter shop is in good standing.  
 
c) A utility shall conduct a referee test of a m eter within 45 days after receiving 
notice from a Commission representative of a customer's request if the meter 
testing facility that the utility uses to conduct the test is located in -state. The 
utility shall conduct the meter test between 7 a.m. and 4 p .m. Monday through      ILLINOIS REGISTER             373 
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 Friday, excluding holidays, at a date and time agreed upon by the utility, the 
customer and the Commission representative, u nless the utility, the customer  and 
the Commission representative agree to a different day or time.  
 
d) A utility  shall conduct a referee test of a meter within 90 days after receiving 
notice from a Commission representative of a customer's request if the meter 
testing facility that the utility uses to conduct the test is located out of state and 
the customer request ing the referee test selects the out -of-state location, unless the 
customer agrees to a later time. The utility shall conduct the meter test between 7 
a.m. and 4 p.m. Monday through Friday, excluding holidays, at a date and time 
agreed upon by the utility,  the customer and the Commission representative, 
unless the utility, the customer  and the Commission representative agree to a 
different day or time.  
 
e) Upon written application to the Commission by a customer and upon notice to a 
utility by a Commission representative, a utility under the oversight of a 
Commission representative shall conduct an accuracy test of a meter that was the 
subject of the written request, provided the customer has not requested a meter 
accuracy test under this Section or under Se ction 501.260 500.260  in the 12 
months prior to the request. A customer shall make a written request for a meter 
test and pay a fee, as provided in this subsection , to the Commission. A utility 
shall inform the customer or a Commission representativ e, upon request,  of the 
size and type of meter used to serve the customer. If the accuracy test indicates 
that the meter over -registers by more than 2.0%, the utility shall refund the fee to 
the customer.  
 
SCHEDULE OF FEES  
Rated capacities in cubic feet per hour Fee 
Diaphragm meters up to 650  $40 
Diaphragm meters from 651 to 1,500  $80 
Diaphragm meters in excess of 1,500  $120  
Rotary meters up to 1,500  $40 
Rotary meters from 1,501 to 12,000  $80 
Rotary meters from in excess of 12,000  $120  
Turbine meter tested in utility shop at atmospheric  
pressure  $120  
Metering types not listed but tested in utility shop  $120  
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 f) If a customer is required to pay the costs of a meter test under Section 
501.260 500.260 because of the type or size of the meter, the customer must  pay 
the utility the same costs under this Section, in addition to the fee to the 
Commission under subsection (e).  
 
g) Upon notice of a referee test from a Commission representative, a utility shall not 
disturb the meter that was the subject of the written  referee test request in any 
manner, unless a Commission representative or the customer provides 
authorization. The utility shall document the authorization by recording the name 
of the person giving the authorization and the date and time of the authoriza tion. 
The utility shall provide this authorization documentation to the Commission 
representative at the time of the referee test.  
 
h) When a utility removes a meter for purposes of a referee test, the utility or 
Commission representative shall deliver the  meter to the utility's meter testing 
facility, and the utility shall secure the meter to prevent potential tampering or 
disturbance from in -service conditions until the referee test begins.  
 
i) A utility shall waive the 12 -month waiting period identified in subsection (e) for 
Commission referee tests if a customer makes one of the following 
demonstrations : 
 
1) A deviation in the customer's measured gas usage in excess of 10% 
occurred following th e utility's installation of a different meter on the 
customer's service and the difference is not attributable to weather or the 
customer's process changes; or  
 
2) Relevant facts that point to potential accuracy problems with the meter.  
 
j) If a utility re moves a meter for testing but before the testing occurs is notified by 
the customer that the customer plans to request a referee test of the meter, the 
utility shall not test the meter and shall secure the meter to prevent potential 
tampering or disturbanc e from in -service conditions until the referee test begins. 
If, after 60 days from when the utility removed the meter for testing, the customer 
has not filed a request with the Commission for a referee test, the utility shall send 
a notice in writing to th e customer informing it of the following:  
 
1) The notice shall state that the customer has 30 days in which to complete 
the request for the Commission referee test.       ILLINOIS REGISTER             375 
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2) If the customer fails to make its request within the 30 days, the utility, at 
its optio n, may conduct the required testing of the meter.  
 
k) The utility is responsible for contacting the Commission to verify the status of the 
customer's request for a referee test prior to testing the meter.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective D ecember 29, 2016)  
 
Section 501.280  Meter Tests Requested by Natural Gas Suppliers  
 
a) Upon a natural gas supplier's request, provided that the utility or manufacturer has 
not tested the meter in question within 12 months prior to the request, a utility 
providing metering service shall test the meter in question within 45 days after 
receiving the request, unless the natural gas supplier agrees to a later time. The 
utility shall perform the meter test between 7 a.m. and 4 p.m. on Monday through 
Friday, exclu ding holidays, unless the utility and the natural gas supplier agree to 
a different day or time. The utility shall inform the customer of the natural gas 
supplier's request and the date and time of the test at least five business days prior 
to the agreed -upon test date. The utility shall perform the test in the presence of a 
representative of the natural gas supplier, unless the natural gas supplier waives 
the right to have a representative present. The utility shall allow the customer or 
its representative  to observe the meter test. The utility shall provide a written 
summary of the results of the meter test to the natural gas supplier and the 
customer within five business days.  
 
b) If a utility or manufacturer has tested a meter within the last 12 months, the utility 
is not obligated to retest the meter in response to the latest request. Instead, the 
utility may offer the results of the last test in response to the latest request.  
 
c) If a requested meter test will not interrupt a customer's gas service, a utility may 
perform a meter test requested by a natural gas supplier at any time agreeable to 
the utility and the natural gas supplier. If a requested meter test will interrupt the 
customer's gas service, then a utility shall obtain permission from a custo mer to 
interrupt the customer's service to perform a requested test.  
 
d) A utility may require a natural gas supplier to pay up to $10,000 ($25,000 if 
performed at a non -affiliated third -party location) for the actual costs of the meter 
test. A utility per forming a meter test at the request of a natural gas supplier shall      ILLINOIS REGISTER             376 
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 refund the natural gas supplier's payment if the meter test shows that the meter is 
under -registering by more than 2.0%. A utility shall provide to a natural gas 
supplier an itemized writt en statement of the cost of a requested meter test, obtain 
the natural gas supplier's agreement to pay the stated cost, and receive payment 
from the natural gas supplier for the requested meter test before taking any action 
to remove the meter or begin the  requested meter test.  
 
e) A natural gas supplier may request a meter test only for a current customer or for 
a prior customer if, at the time of the request, the supplier had provided gas 
supply to that customer within the prior three months.  
 
f) A natura l gas supplier may request a Commission referee test of a meter under the 
provisions of  subsection (c) and Section 501.270 500.270 , and shall be responsible 
for the fee prescribed by Section 501.270 (e)500.270(e)  and the actual cost, not to 
exceed $10,000, of the test. The utility shall inform the customer of the natural 
gas supplier's request and the date and time of the referee test at least five 
business days prior to the agreed upon test date. The utility shal l perform the 
referee test in the presence of a representative of the natural gas supplier, unless 
the natural gas supplier waives the right to have a representative present. The 
utility shall allow the customer or its representative to observe the meter t est. If 
the meter over -registers by more than 2.0%, the utility shall refund all fees it 
charged to the natural gas supplier and make any necessary meter data 
adjustment.  
 
g) A utility shall conduct a referee test of a meter within 45 days after receiving 
notice from a Commission representative of a natural gas supplier's request if the 
meter testing facility that the utility uses to conduct the test is located in -state, 
unless the supplier agrees to a later time. The utility shall conduct the meter test 
between 7 a.m. and 4 p.m. Monday through Friday, excluding holidays, unless the 
utility, the third party supplier, and Commission representative agree to a different 
day or time.  
 
h) A utility shall conduct a referee test of a meter within 90 days after rece iving 
notice from a Commission representative of a natural gas supplier's request if the 
meter testing facility that the utility uses to conduct the test is located out of state, 
unless the supplier agrees to a later time. The utility shall conduct the met er test 
between 7 a.m. and 4 p.m. Monday through Friday, excluding holidays, unless the 
utility, the third party supplier, and Commission representative agree to a different 
day or time.       ILLINOIS REGISTER             377 
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(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)  
 
SUBPART E:  EXTENSION OF MAINS  
 
Section 501.610  Extension of Distribution Mains in Rural Areas  
 
a) Rural Customer  
 
1) A utility shall consider a customer whose premises are not located in 
urban territory , as described in Section 501.600 500.600 , as a rura l 
customer.  
 
2) The provisions of this Section shall not apply to applicants for service 
under tariffs allowing interruptions of service. A utility with service tariffs 
that allow the utility to interrupt service to a customer shall file with the 
Commissio n an extension provision or an agreement with the applicant 
that shall govern main extensions for service under those tariffs.  
 
b) Extension Provisions  
 
1) If a utility determines that a main extension is necessary to provide firm 
gas service for an applicant or group of applicants whose premises are 
located in rural areas within which the utility operates, the utility, upon 
written request for service by the applicants, shall make the necessary 
main extension along a street, highway or other right -of-way to the nearest 
point or points adjacent to the point of connection with the service piping 
of such applicants, upon agreement by the applicant or group of ap plicants 
to comply with the provisions of this Section.  
 
A) A utility may file , in conjunction with its rate schedule , a main 
extension provision that would provide  the utility customer with 
the choice of obtaining the extension under the provision or unde r 
subsection (b)(1)(C). If a utility files a main extension provision 
and the Commission permits it to become effective, the applicant 
may, at his or her election, proceed either under the provision or 
under subsection (b)(1)(C).  
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 B) A utility may file a m ain extension provision that operates in place 
of, and not as an alternative to, subsection (b)(1)(C), but in that 
case the main extension provision shall not become effective 
except after a showing that it is generally more favorable to 
applicants than ar e the pro visions of subsection (b)(1)(C)  and, after 
specific action by the Commission by order or otherwise, 
permitting the provision to become effective. If the provision 
becomes effective, it shall govern the making of extensions.  
 
C) Deposits for Extens ions 
 
i) The utility may require the applicant or group of applicants 
to deposit with the utility the estimated cost of the 
extension determined in the manner desig nated in 
subsection (c). Each sub sequent customer to be connected 
within a period of 10 ye ars from the date o f making the 
original extension  shall be required to deposit with the 
utility an amount equal to the sum of the estimated cost of 
the existing extension plus the estimated cost of any further 
extension necessary to serve the customer, di vided by the 
number of depositors for the entire extension. The excess of 
this deposit over the estimated cost of any further extension 
necessary to serve the customer shall be divided equally by 
the utility among the previous depositors for the extension 
and shall be refunded to them in that amount. In no case 
shall the amount of the refund to a customer exceed the 
customer's deposit, nor shall the total of deposits for any 
exten sion exceed the estimated cost of making the 
extension.  
 
ii) The foregoing pr ovisions depend upon agreement by 
applicants that deposits of applicants will be equal. If an 
applicant or group of applicants request s a new extension to 
an existing main that would increase present customers' 
deposits, the utility shall consider the new extension as an 
original extension and shall not require deposits from 
existing customers for the requested new original 
extension.  
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 iii) If the point of connection with the service piping of an 
applicant is so located that the applicant could be served by  
extending a separate parallel main at less cost than the 
amount of deposit that would be required from the 
applicant for connection to the existing extension, a utility 
will not require the applicant to deposit in excess of the 
estimated cost of the separ ate main , and the applicant shall 
not share in any refunds so long as the applicant's deposit 
remains less than that of the other depositors on the existing 
extension.  
 
2) A utility, when reaching agreement with a group of applicants, shall 
consider the gr oup to be governed by the majority as applied to any 
specific extension.  
 
c) A utility shall provide the applicant with a free estimate of the cost of the 
requested main extension along the expected route for the main extension 
designated by the utility. A  utility shall also provide a free estimate of the cost of 
an alternative route if the applicant requests an alternative route and the utility 
expects the cost for the alternative route to not exceed the cost from the expected 
route by more than 50%.  
 
d) A utility shall use, as the basis for determining the amount of a deposit, the 
distance the applicant is from the nearest available distribution main and a route 
that the utility would normally follow in making the extension and over which 
right -of-way is a vailable.  
 
e) A utility may petition the Commission for an investigation and determination of 
the reasonableness of any main extension if circumstances indicate that the 
additional revenues generated as a result of the main extension would be so 
meager as to make it unlikely to pay a fair compensation to the utility for its 
investment, operation, maintenance and replacement of the extension, or that , for 
other substantial reasons , the extension is unwarranted. If  after a hearing the 
Commission orders a util ity to construct an extension that has been challenged on 
any of these grounds, the applicant or group of applicants shall reimburse the 
utility for the construction costs to the extent necessary to ensure that the utility 
earns the Commission -authorized r eturn from the required investment.  
 
(Source:  Amended at 41 Ill. Reg. 351, effective December 29, 2016)