Mandatory Greenhouse Gas 

Reporting Rule: EPA’s 

Response to Public Comments 

Subpart SS: Electrical Equipment 

Manufacture or Refurbishment 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 2 

FOREWORD 

This document provides responses to public comments on the U.S. Environmental Protection Agency’s 

(EPA’s) Proposed Mandatory Greenhouse Gas Reporting Rule: Additional Sources of Fluorinated GHGs: 

Subpart SS, Electrical Equipment Manufacture or Refurbishment. EPA published a Notice of Proposed 

Rulemaking in the Federal Register (FR) on April 12, 2010 (75 FR 18652). EPA received comments on 

this proposed rule via mail, e-mail, and at a public hearing held in Washington D.C. on April 20, 2010. 

Copies of all comments submitted are available at the EPA Docket Center Public Reading Room. 

Comments letters and transcripts of the public hearings are also available electronically through 

http://www.regulations.gov by searching Docket ID EPA-HQ-OAR-2009-0927. 

EPA prepared this document in multiple sections, with each section focusing on a different broad 

category of comments on the rule. In light of the large number of comments received and the significant 

overlap between many comments, this document does not respond to each comment individually. Rather, 

EPA summarized and provided a single response to each significant argument, assertion, and question 

contained within the totality of comments. Within each comment summary, EPA provides in parentheses 

one or more lists of Docket ID numbers for commenters who raised particular issues; however, these lists 

are not meant to be exhaustive, and EPA does not individually identify each and every commenter who 

made a certain point in all instances, particularly in cases where multiple commenters expressed 

essentially identical arguments. 

EPA’s responses to comments are generally provided immediately following each comment summary. In 

some cases, EPA provided responses to specific comments or groups of similar comments in the 

preamble to the final rulemaking. Rather than repeating those responses in this document, EPA has 

referenced the preamble. 

Comments were assigned to specific section of this document based on an assessment of the principal 

subject of the comment; however, some comments inevitably overlap multiple subject areas. 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 3 

Table of Contents 

1. Definition of the Source Category ........................................................................................................4 

1.1 Installation of Electrical Equipment at Electric Power Systems.......................................................4 

2. Reporting Threshold.............................................................................................................................6 

3. Detailed GHG Emission Calculation Procedures/Equations in the Rule..............................................7 

3.1. Method for Estimating Disbursements to Customers ......................................................................7 

3.2. Certification of Quantity Charged in Equipment...............................................................................7 

3.3. Over-charging equipment.................................................................................................................8 

4. Monitoring and QA/QC Requirements................................................................................................10 

4.1. Accuracy and Precision of Scales..................................................................................................10 

4.2. Other ..............................................................................................................................................11 

Appendix A – List of Commenters Sorted by Submission Number ............................................................12 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 4 

1. Definition of the Source Category 

Relevant Bin Numbers: 6.1.2 and 6.1.2.2 

1.1 Installation of Electrical Equipment at Electric Power Systems 

Comment Summary 1.1-a: Two commenters (0125, 0126) supported the notion that the manufacturer 

installing the equipment should be responsible for reporting the emissions before transferring custody of 

the equipment. Commenter 0125 “seeks clarification on the intersection of the facility definitions” 

between subpart DD and subpart SS given that often times an electrical equipment manufacturer is 

contracted for delivery to and installation at an electric power transmission or distribution facility. New 

equipment that is installed “could potentially operate “as an integrated unit” as part of the electrical grid 

before the utility takes ownership”; to that end, the proposed language “could require a transfer of the 

reporting requirement from the subpart SS entity to the subpart DD entity at the moment of first 

connection.” Commenter 0125 expresses concern that such a scenario would create significant 

administrative burdens for all parties. To simplify this burden, Commenter 0125 proposed that the 

definition of a facility include “the job site where new equipment installation occurs” such that “the owner 

of the gas, typically the equipment manufacturer or a third party, would be responsible for reporting until 

the title to the gas and equipment has been transferred to the customer.” Commenter 0125 proposed to 

add clarifying text to both subparts DD and SS about the reporting requirements with respect to 

equipment installation. For subpart DD, Commenter 0125 proposed adding the text, “For equipment 

installed but not yet owned, the reporting requirements under this subpart begin when the title to the 

equipment is transferred to the utility or third party.” For subpart SS, Commenter 0125 proposed adding 

“installation” to the language regarding GHGs to report. 

One commenter (0129) recommended that there be a separate subpart of the MRR to cover emissions 

from equipment installation because the gas owner could be electrical equipment manufacturer, the 

electric power transmission or distribution facility, or a third party contracted by either the electrical 

equipment manufacturer or the customer. Commenter 0129 cited other reasons for having a separate 

subpart including the difficulty in measuring emission losses downstream of the flowmeter and the need 

for two different emissions calculations in Subpart SS. Commenter 0129 expressed concern over which 

subpart a third party that is hired to purchase gas and perform installation would follow. 

Response 1.1-a: EPA recognizes that some equipment, namely gas insulated substations, is typically 

assembled by the manufacturer onsite and that it can take several months to complete assembly, 

inspection, and final acceptance and commissioning. For these projects, gas accounting is best done by 

the manufacturer that is assembling the equipment and handling the gas that will be installed into the 

equipment. Based on EPA’s review of these comments, the final rule specifies that the responsibility of 

reporting emissions from installation practices is dependent upon the point at which the title is transferred 

to the electric power transmission or distribution entity by the equipment manufacturer or third-party 

contracted by the manufacturer. 

In instances when the title to the equipment has not yet been transferred to the electric power 

transmission or distribution facility (regardless of whether the equipment manufacturer holds the title or 

the title temporarily passes from the equipment manufacturer to a third party contractor), and the 

equipment is at the electric power transmission or distribution facility, the equipment manufacturer must 

estimate and report emissions from equipment installation using the equipment installation mass balance 

equation. In instances when the title of the equipment has been transferred to the electric power 

transmission or distribution facility, the electric power transmission or distribution facility must estimate 

and report emissions during installation by accounting for the amount of gas inside the equipment, upon 

the date of the title transfer to the electric power transmission or distribution entity, in the mass balance 

acquisition input. If the title of the equipment has already been transferred to the electric power 

transmission or distribution entity and the installation is conducted by a third party, then the electric power 

transmission or distribution facility would still be responsible for reporting emissions during installation.. 

EPA disagrees with the need for a separate subpart to cover emissions from equipment installation. In 

instances when a third party is contracted to conduct the installation, the equipment manufacturer 

remains obligated to report the emissions unless title has transferred to the electric power system. 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 5 

As explained in section V of the preamble of the 2009 final rule, all reporters must select a designated 

representative (DR) who is responsible for certifying, signing, and submitting all submissions to EPA. The 

DR has the flexibility to delegate duties, such as the preparation of submissions, but retains the ultimate 

responsibility to sign and certify all submissions. See, 58 FR 3590, 3598 (Jan. 11, 1993). Furthermore, 

while the DR or his delegatee may need to acquire necessary reporting information from a third party, the 

DR must make the appropriate inquiries and certification when reporting; ultimate responsibility rests and 

must necessarily rest on him or her. The DR may provide in contracts, leases, or other agreements with 

third parties that true, accurate, and correct reporting information must be provided to the DR in a timely 

fashion. If the third party fails to provide timely, true, accurate, or correct information to the DR, then the 

DR has recourse contractually, or otherwise, on the third party. For more information see section V of the 

2009 final rule (74 FR 56260) and the Mandatory Greenhouse Gas Reporting Rule: EPA’s Response to 

Public Comments, Volume 11, Designated Representative and Data Collection, Reporting, Management 

and Dissemination (EPA-HQ-OAR-2008-0508). 

 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 6 

 

2. Reporting Threshold 

Relevant Bin Number: 6.2 

Comment Summary 2-a: One commenter (0125) requested that sealed and unused gas cylinders 

should not count toward the reporting threshold. Commenter 0125 explained that electrical equipment 

manufacturers “purchase sealed cylinders for bundled deliveries of gas and equipment”, and as such, 

their seals remain intact and no leakages can occur. The commenter referenced the 10% leak rate as 

cited in the preamble, which was based on a 2002 CIGRÉ article. According to the commenter, the 

article omitted mention of storage when describing OEM gas purchases as “partly banked in newly 

installed equipment and partly lost during testing, manufacturing, and commissioning.”1

 

Response 2-a: EPA disagrees that sealed and unused cylinders should not count toward the reporting 

threshold. EPA recognizes that sealed cylinders are unlikely to be a major source of emissions and that it 

has been the standard practice by some manufacturers to deliver sealed cylinders with new equipment. 

However, EPA is concerned that not including these cylinders could introduce complications in tracking 

gas in cylinders and other containers because of the need to differentiate those cylinders that are sealed 

and destined for the customer and those cylinders that are sealed and destined for use by the electrical 

equipment manufacturer. Further it would be virtually impossible for an audit of threshold and cylinder 

record keeping requirements to distinguish the different use of cylinders at the beginning and end of the 

year. Therefore, EPA finalized the requirement that sealed and unused cylinders count toward the 

determination of the reporting threshold. 

1

 P. O’Connell, F. Heil, J. Henriot, G. Mauthe, H. Morrison, L. Niemeyer, M. Pittroff, R. Probst, J.P. Taillebois, “SF6 in 

the Electric Industry, Status 2000,” CIGRÉ Electra, February 2002, pg. 16 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 7 

3. Detailed GHG Emission Calculation Procedures/Equations in the Rule 

3.1. Method for Estimating Disbursements to Customers 

Relevant Bin Number: 6.4.1 and 6.4.2 

Comment Summary 3.1-a: Two commenters (0125, 0128) supported the need to quantify emissions 

that occur during SF6 disbursement activities. Commenter 0128 supported a combination of flow meters 

and engineering estimates to determine the emission loss downstream of the container filling the 

equipment or cylinder but opposes the use of a nameplate capacity technique that would require an 

“involved and uncertain statistical correction method.” Commenter 0125 was concerned that “the 

proposed rule could require an inordinate administrative burden to record the numerous parameters for 

individual fill operations.” Commenter 0125 recommended “applying a statistical calculation such as a 

midpoint or average to all fill operations”, which would not need to be rerecorded for each operation. 

Response 3.1-a: EPA recognizes that developing a representative loss factor that can be used for all 

filling events is more practical than performing measurements for each individual fill operation. EPA 

agrees with the commenters that direct measurement would be burdensome in this circumstance. 

Consequently, rather than requiring actual measurements as proposed, EPA is allowing reporters to 

account for variability in the diameters and fittings of hoses supplied by various manufacturers and 

applied under varying conditions and requiring an emission factor be calculated for each hose and valve, 

or fitting, combination. For each hose-valve combination, the calculated emission factor must be 

multiplied by the number of annual fill operations that use that hose-valve arrangement. The calculation 

must be recalculated annually to account for changes to the specifications of the valves or hoses that 

may occur throughout the year. In addition, EPA is requiring electrical equipment manufacturers to 

account for SF6 or PFC emissions that occur as a result of unexpected events or accidental losses, such 

as a malfunctioning hose or leak in the flow line, during the filling of equipment or containers for 

disbursement. If there is a sudden rise in the quantity of SF6 or PFC gas that is needed to fill a certain 

make and model to its shipping charge, or nameplate capacity, this may be indicative of a leak in the 

lines. It is good practice to note unusual changes to the quantities used to fill equipment. 

In addition, although one commenter opposes the use of a nameplate capacity technique, to increase 

flexibility, EPA is providing this additional option for determining the mass of SF6 or the PFCs disbursed 

to customers in new equipment. EPA is allowing the equipment’s nameplate capacity or, in cases where 

equipment is shipped with a partial charge, the equipment’s partial shipping charge to be assumed as 

equal to the disbursement. A sufficiently precise estimate of the nameplate capacity for each make and 

model of equipment must be determined through a number of measurements. The number of 

measurements required must be calculated to achieve a precision of one percent of the true mean, using 

a 95 percent confidence interval. 

Comment Summary 3.1-b: Commenter 0075 acknowledged that flow meters may be appropriate for 

certain manufacturer SF6 disbursement procedures but does not support the use of flow meters by the 

electrical transmission or distribution facility because they are not currently available and crews are not 

presently trained in their use. “Weighing of cylinders has proven to provide a good measure of facility 

inventory and emissions.” 

Response 3.1-b: EPA is not requiring the use of flowmeters by the electrical transmission or distribution 

facility under Subpart DD of the final rule. Under Subpart SS, electrical equipment manufacturers are 

required to estimate the mass of SF6 or PFCs disbursed to customers in new equipment or cylinders by 

monitoring the mass flow of the SF6 or PFCs into the new equipment or cylinders using a flowmeter or by 

weighing containers before and after gas is filled into equipment or cylinders. For more information 

regarding the cylinder tracking and weighing requirements for electrical transmission or distribution 

facilities, please see section DD of the preamble and final rule. 

3.2. Certification of Quantity Charged in Equipment 

Relevant Bin Number: 6.4.3 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 8 

Comment Summary 3.2-a: Seven commenters (0075, 0081, 0083, 0094, 0097, 0098, 0126) supported 

requiring that electrical equipment manufacturers certify the quantity of SF6 or PFC contained in 

equipment that is delivered inside equipment. Commenter 0081 recommended that the quantity of gas 

certified in delivered equipment be “expressed in pounds and not in terms of pressure, volume and 

temperature.” 

Commenter 0083 asserted that electric transmission or distribution facilities are “currently unable to obtain 

accurate information on the amount of gas used for the residual charge, or the amount of gas shipped in 

cylinders alongside new equipment, or even an accurate nameplate capacity for the new piece of 

equipment.” Commenter 0083 supported the inclusion of electrical equipment manufacturers in the rule 

and requiring that they provide to the customer an accounting of the amount of SF6 disbursed to the 

electrical equipment user and an accurate nameplate capacity for the equipment. Commenter 0083 

stated that “since equipment manufacturers will already be tracking their SF6 disbursements, sharing this 

information with the equipment users will not be burdensome.” 

Commenters 0097 and 0098 both supported that the electrical equipment manufacturer should certify 

both the weight of that gas and the nameplate SF6 weight; commenters 0097 and 0094 state that the 

nameplate SF6 weight should be expressed at rated pressure and standard temperature. 

Response 3.2-a: After reviewing the comments received, EPA concludes that the electrical equipment 

manufacturer should certify the quantity of gas provided in delivered equipment as it represents two 

inputs to two mass balance equations—a disbursements input of the mass-balance equation used by 

manufacturers (i.e., sales of SF6 to other entities, including gas in equipment that is sold) and an 

acquisitions input of the mass-balance equation used by electric power systems (i.e., gas with or 

alongside equipment). Additionally, EPA concludes that the electrical equipment manufacturer should 

certify the quantity of gas charged into the equipment at installation as it represents the acquisition input 

to the electric power systems’ mass balance equation. The validity of the mass-balance approach is 

dependent on precise inputs, consequently, inaccuracies of even two or three percent could lead to 

unacceptably large inaccuracies in emissions estimates. The final rule includes a requirement for 

electrical equipment manufacturers to maintain such certifications as records and to express the quantity 

in pounds of SF6 or PFC gas. Electrical equipment manufacturers should provide copies of the 

certifications to electric power systems upon request. 

3.3. Over-charging equipment 

Relevant Bin Number: 6.4.4 

Comment Summary 3.3-a: Three commenters (0075, 0097, and 0098) provided comment to EPA’s 

request for information on over-charging electrical equipment during installation and commissioning. 

Commenter 0075 stated that such a practice is not allowed by their company’s operating, maintenance, 

and safety procedures. Commenters 0097 and 0098 recommended that the electrical equipment 

manufacturer “be responsible for the associated emissions of any overcharge of SF6 when OEMs 

[electrical equipment manufacturers] install and commission equipment at the electric transmission or 

distribution facility.” 

Response 3.3-a: EPA recognizes that emissions associated with an overcharge can occur at different 

points in time during the lifetime of the equipment. Associated emissions from over-charging are 

discussed further in the Subpart SS Technical Support Document, “Technical Support Document for 

Emissions from Electric Equipment Manufacture or Refurbishment and Manufacturing of Electrical 

Components.” Please see this document, available in the docket (Docket ID No. EPA-HQ-OAR-2009-

0927) and online, for more information. 

Additionally, EPA recognizes the need for accuracy of the data inputs required to estimate emissions of 

SF6 from electrical equipment use. Therefore, EPA is requiring in the final rule that the quantity of gas 

charged into delivered equipment and added during installation by the manufacturer be certified by the 

manufacturer and expressed in pounds of SF6 or PFC. Electrical equipment manufacturers must keep 

records of certifications of the quantity of gas, in pounds, charged into equipment at the electrical 

equipment manufacturer or refurbishment facility as well as the actual quantity of gas, in pounds, charged 

into equipment at installation. This certification requirement will ensure that the equipment user knows 

the exact amount of gas contained within the equipment that arrives to its electric transmission or 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 9 

distribution facility in order to satisfy subpart DD reporting requirements. It is the equipment user’s 

responsibility to be aware of any overcharge and document this overcharge in their mass-balance 

emissions monitoring. 

Lastly, the requirements of the final rule distinguish the reporting boundary between subparts DD and SS 

by requiring electrical equipment manufacturers to estimate and report the annual SF6 and PFC 

emissions from the equipment being installed on the electric power system’s premises until the title of the 

equipment has transferred to the electric power transmission or distribution entity. For more information 

on reporting boundaries, please see the response to comment under 1.1a, above. 

 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 10 

4. Monitoring and QA/QC Requirements 

4.1. Accuracy and Precision of Scales 

Relevant Bin Number: 6.4.2 

Comment Summary 4.1-a: Two commenters (0118, 0125) provided comment on the proposed accuracy 

and precision requirements for scales used by electrical equipment manufacturers. Commenter 0118 

agreed that “scales used to weigh the SF6 cylinders need to be calibrated and within one percent 

accuracy.” Conversely, commenter 0125 disagreed with the proposed requirement. Commenter 0125 is 

concerned that such a level of accuracy "will be unattainable in practice because scales currently in use 

have an accuracy of ±2 pounds.” With the current accuracy of ±2 pounds, “a gas cylinder returned with 

10 pounds of residual gas would result in a potential gas weight error of 20 percent. A one percent 

accuracy requirement would require a scale with an accuracy of ±0.1 pounds, or 200 times more precise 

than currently in use.” The commenter (0125) believed that despite the proposed rule allowance of “best 

available” measurement accuracies in the 2011 reporting year, the one percent accuracy will not be 

attainable by 2012. Commenter 0125 recommended “an accuracy requirement that is no stricter than 10 

percent for residual gas amounts.” 

Response 4.1-a: The proposed rule would have required that scales be accurate and precise to within 

±1 percent of the true weight or better. Based on these commenters’ concerns, EPA conducted an 

analysis, as described in the Technical Support Document for Emissions from Electrical Equipment 

Manufacture or Refurbishment and Manufacturing of Electrical Equipment Components, on two 

hypothetical electrical equipment manufacturer facilities to examine the effect of those accuracies and 

precisions on the relative uncertainty of facility-level emissions estimates. The findings indicated that the 

incremental increase in relative uncertainty from a requirement of ± 1 percent of true mass or weight scale 

accuracy to ± 2 pounds scale accuracy was not enough to justify a more stringent accuracy of 1 percent 

and its associated burden. Based on this review, EPA has changed the requirements for scale accuracy 

and precision. 

The final rule requires that quantities required by the equations in this subpart have been measured using 

either flowmeters with an accuracy and precision of ±1 percent of full scale or better or scales with an 

accuracy and precision of ±1 percent of the filled weight (gas plus tare) of the containers of SF6 or PFCs 

that are typically weighed on the scale.. For scales that are generally used to weigh cylinders containing 

115 pounds of gas when full, this equates to ±1 percent of the sum of 115 pounds and approximately 120 

pounds tare, or slightly more than ± 2 pounds. This absolute accuracy requirement, expressed as a 

percentage of the filled weight of the container that is weighed on the scale, is less stringent than the 1 

percent (of true weight) relative accuracy requirement in the proposed rule. EPA concluded this change 

will lower the burden on reporters without significant compromise to data quality. For more information on 

scale accuracy and precision, please see the Subpart SS Technical Support Document, “Technical 

Support Document for Emissions from Electric Equipment Manufacture or Refurbishment and 

Manufacturing of Electrical Components” available in the docket (Docket ID No. EPA-HQ-OAR-2009-

0927) and online. 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 11 

4.2. Other 

Relevant Bin Number: 6.5.3 

Comment Summary 4.2-a: Commenter 0075 emphasized that the issue of accurately determining 

nameplate capacity primarily impacts manufacturers of equipment. Commenter 0075 stated that their 

company’s equipment has a nameplate capacity, regardless of the equipment age, which is provided by 

the manufacturer and/or from a physical plate attached to the equipment. Commenter 0075 expressed 

concern of a requirement to measure nameplate capacity, stating that “existing facility equipment must be 

grandfathered” from any such requirement, because any capacity measurement procedure for in-service 

equipment would be “unacceptably disruptive for the electric power system and the customers and would 

likely result in the release of at least some SF6.”

Response 4.2-a: EPA agrees about the need to accurately determine nameplate capacity and that it 

primarily impacts electrical equipment manufacturers. For more information regarding the requirement for 

electrical equipment manufacturers to certify the quantity of gas provided in delivered equipment and the 

quantity of gas charged into the equipment at installation, please see response 3.2-a above. Regarding 

the commenter’s concern about measuring nameplate capacity, EPA reiterates that this requirement of 

measuring nameplate capacity to accurately determine disbursements was proposed for the electrical 

equipment manufacturer under Subpart SS only and does not extend to in-service equipment at electrical 

transmission or distribution facilities per Subpart DD.

Comment Summary 4.2-b: Commenter 0075 stated that the final wording of the mandatory reporting 

rule should preserve the practice whereby electric transmission or distribution facilities receive new 

equipment with a minimum, positive charge of SF6 and filled by trained personnel at the electric 

transmission or distribution facility using SF6 from the company inventory rather than purchasing the 

equipment fully charged with SF6 or with an accompanying set of SF6 cylinders.

Response 4.2-b: The final rule has no bearing on the continued practice described by this commenter. 

Electrical transmission or distribution facilities may receive new equipment with a minimum, positive 

charge and have their personnel fill the remaining charge using gas from their inventory. This rule 

contains reporting requirements but does not dictate where or by whom equipment must be filled. 
 

November 8, 2010 Subpart SS: Electrical Equipment Manufacture or Refurbishment 12 

Appendix A – List of Commenters Sorted by Submission Number 

Submission No. Commenter Organization 

EPA-HQ-OAR-2009-0927-0075 Kenneth Boyd Southern Company 

EPA-HQ-OAR-2009-0927-0081 Kenneth Boyd Southern Company 

EPA-HQ-OAR-2009-0927-0083 Deborah Boyle Oncor 

EPA-HQ-OAR-2009-0927-0094 Alexander G. Taft National Grid 

EPA-HQ-OAR-2009-0927-0097 Michael Bradley The Clean Energy Group 

EPA-HQ-OAR-2009-0927-0098 Rayburn L. Butts Nextera Energy, Inc. 

EPA-HQ-OAR-2009-0927-0118 Mitchell C. Contreras Center Point Energy 

EPA-HQ-OAR-2009-0927-0125 Eric Hsieh 

National Electric Managers 

Association 

EPA-HQ-OAR-2009-0927-0126 Wesley McNealy Pepco Holdings, Inc. 

EPA-HQ-OAR-2009-0927-0128 Pamela Campos Environmental Defense Fund 

EPA-HQ-OAR-2009-0927-0129 David Giegel Mitsubishi Electric Power Products