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Subpart DD—Electrical Transmission and Distribution Equipment 

Use

§ 98.300 Definition of the source category.

(a) The electrical transmission and distribution equipment 

use source category consists of all electric transmission and 

distribution equipment and servicing inventory insulated with or 

containing sulfur hexafluoride (SF6) or perfluorocarbons (PFCs) 

used within an electric power system. Electric transmission and 

distribution equipment and servicing inventory includes, but is 

not limited to:

(1) Gas-insulated substations.

(2) Circuit breakers.

(3) Switchgear, including closed-pressure and hermetically 

sealed-pressure switchgear and gas-insulated lines containing SF6

or PFCs.

(4) Gas containers such as pressurized cylinders.

(5) Gas carts.

(6) Electric power transformers.

(7) Other containers of SF6 or PFC.

§ 98.301 Reporting threshold.

(a) You must report GHG emissions from an electric power 

system if the total nameplate capacity of SF6 and PFC containing 

equipment (excluding hermetically sealed-pressure equipment) 

located within the facility, when added to the total nameplate 
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capacity of SF6 and PFC containing equipment (excluding 

hermetically sealed-pressure equipment) that is not located 

within the facility but is under common ownership or control, 

exceeds 17,820 pounds and the facility meets the requirements of 

§98.2(a)(1).

(b) A facility other than an electric power system that is 

subject to this part because of emissions from any other source 

category listed in Table A–3 or A–4 in subpart A of this part is 

not required to report emissions under subpart DD of this part 

unless the total nameplate capacity of SF6 and PFC containing 

equipment located within that facility exceeds 17,820 pounds.

§ 98.302 GHGs to report.

You must report total SF6 and PFC emissions from your 

facility (including emissions from fugitive equipment leaks, 

installation, servicing, equipment decommissioning and disposal, 

and from storage cylinders) resulting from the transmission and 

distribution servicing inventory and equipment listed in 

§98.300(a). For acquisitions of equipment containing or 

insulated with SF6 or PFCs, you must report emissions from the 

equipment after the title to the equipment is transferred to the 

electric power transmission or distribution entity.

§ 98.303 Calculating GHG emissions.

(a) Calculate the annual SF6 and PFC emissions using the 

mass-balance approach in Equation DD–1 of this section:
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(Eq. DD-1)

Where:

Decrease in SF6 Inventory = (pounds of SF6 stored in containers, 

but not in energized equipment, at 

the beginning of the year)—(pounds of 

SF6 stored in containers, but not in 

energized equipment, at the end of 

the year).

Acquisitions of SF6 = (pounds of SF6 purchased from 

chemical producers or distributors in 

bulk) + (pounds of SF6 purchased from 

equipment manufacturers or 

distributors with or inside 

equipment, including hermetically 

sealed-pressure switchgear) + (pounds 

of SF6 returned to facility after 

off-site recycling).

Disbursements of SF6 = (pounds of SF6 in bulk and contained 

in equipment that is sold to other 

entities) + (pounds of SF6 returned 

to suppliers) + (pounds of SF6 sent 

off site for recycling) + (pounds of 

SF6 sent off-site for destruction).

Net Increase in Total Nameplate Capacity of Equipment Operated

= (The Nameplate Capacity of new 

equipment in pounds, including hermetically 

sealed-pressure switchgear)—(Nameplate 

Capacity of retiring equipment in pounds, 

including hermetically sealed-pressure 

switchgear). (Note that Nameplate Capacity 

refers to the full and proper charge of 

equipment rather than to the actual charge, 

which may reflect leakage).

(b) Use Equation DD–1 of this section to estimate emissions 

of PFCs from power transformers, substituting the relevant 

PFC(s) for SF6 in the equation.

§ 98.304 Monitoring and QA/QC requirements.
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(a) For calendar year 2011 monitoring, you may follow the 

provisions of §98.3(d)(1) through (d)(2) for best available 

monitoring methods rather than follow the monitoring 

requirements of this section. For purposes of this subpart, any 

reference in §98.3(d)(1) through (d)(2) to 2010 means 2011, to 

March 31 means June 30, and to April 1 means July 1. Any 

reference to the effective date in §98.3(d)(1) through (d)(2)

means February 28, 2011.

(b) You must adhere to the following QA/QC methods for 

reviewing the completeness and accuracy of reporting:

(1) Review inputs to Equation DD–1 of this section to 

ensure inputs and outputs to the company's system are included.

(2) Do not enter negative inputs and confirm that negative 

emissions are not calculated. However, the Decrease in SF6

Inventory and the Net Increase in Total Nameplate Capacity may 

be calculated as negative numbers.

(3) Ensure that beginning-of-year inventory matches end-ofyear inventory from the previous year.

(4) Ensure that in addition to SF6 purchased from bulk gas 

distributors, SF6 purchased from Original Equipment Manufacturers 

(OEM) and SF6 returned to the facility from off-site recycling 

are also accounted for among the total additions.

(c) Ensure the following QA/QC methods are employed 

throughout the year:
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(1) Ensure that cylinders returned to the gas supplier are 

consistently weighed on a scale that is certified to be accurate 

and precise to within 2 pounds of true weight and is 

periodically recalibrated per the manufacturer's specifications. 

Either measure residual gas (the amount of gas remaining in 

returned cylinders) or have the gas supplier measure it. If the 

gas supplier weighs the residual gas, obtain from the gas 

supplier a detailed monthly accounting, within ± 2 pounds, of 

residual gas amounts in the cylinders returned to the gas 

supplier.

(2) Ensure that cylinders weighed for the beginning and end 

of year inventory measurements are weighed on a scale that is 

certified to be accurate and precise to within 2 pounds of true 

weight and is periodically recalibrated per the manufacturer's 

specifications. All scales used to measure quantities that are 

to be reported under §98.306 must be calibrated using 

calibration procedures specified by the scale manufacturer. 

Calibration must be performed prior to the first reporting year. 

After the initial calibration, recalibration must be performed 

at the minimum frequency specified by the manufacturer.

(3) Ensure all substations have provided information to the 

manager compiling the emissions report (if it is not already 

handled through an electronic inventory system).
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(d) GHG Monitoring Plans, as described in §98.3(g)(5), must 

be completed by April 1, 2011.

§ 98.305 Procedures for estimating missing data.

A complete record of all measured parameters used in the 

GHG emissions calculations is required. Replace missing data, if 

needed, based on data from equipment with a similar nameplate 

capacity for SF6 and PFC, and from similar equipment repair, 

replacement, and maintenance operations.

§ 98.306 Data reporting requirements.

In addition to the information required by §98.3(c), each 

annual report must contain the following information for each 

electric power system, by chemical:

(a) Nameplate capacity of equipment (pounds) containing SF6

and nameplate capacity of equipment (pounds) containing each 

PFC:

(1) Existing at the beginning of the year (excluding 

hermetically sealed-pressure switchgear).

(2) New during the year (all SF6 -insulated equipment, 

including hermetically sealed-pressure switchgear).

(3) Retired during the year (all SF6 -insulated equipment, 

including hermetically sealed-pressure switchgear).

(b) Transmission miles (length of lines carrying voltages 

above 35 kilovolt).
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(c) Distribution miles (length of lines carrying voltages 

at or below 35 kilovolt).

(d) Pounds of SF6 and PFC stored in containers, but not in 

energized equipment, at the beginning of the year.

(e) Pounds of SF6 and PFC stored in containers, but not in 

energized equipment, at the end of the year.

(f) Pounds of SF6 and PFC purchased in bulk from chemical 

producers or distributors.

(g) Pounds of SF6 and PFC purchased from equipment 

manufacturers or distributors with or inside equipment, 

including hermetically sealed-pressure switchgear.

(h) Pounds of SF6 and PFC returned to facility after offsite recycling.

(i) Pounds of SF6 and PFC in bulk and contained in equipment 

sold to other entities.

(j) Pounds of SF6 and PFC returned to suppliers.

(k) Pounds of SF6 and PFC sent off-site for recycling.

(l) Pounds of SF6 and PFC sent off-site for destruction.

§ 98.307 Records that must be retained.

In addition to the information required by §98.3(g), you 

must retain records of the information reported and listed in 

§98.306.

§ 98.308 Definitions.
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Except as specified in this section, all terms used in this 

subpart have the same meaning given in the Clean Air Act and 

subpart A of this part.

Facility, with respect to an electric power system, means

the electric power system as defined in this paragraph. An 

electric power system is comprised of all electric transmission 

and distribution equipment insulated with or containing SF6 or 

PFCs that is linked through electric power transmission or 

distribution lines and functions as an integrated unit, that is 

owned, serviced, or maintained by a single electric power 

transmission or distribution entity (or multiple entities with a 

common owner), and that is located between: (1) The point(s) at 

which electric energy is obtained from an electricity generating 

unit or a different electric power transmission or distribution 

entity that does not have a common owner, and (2) the point(s) 

at which any customer or another electric power transmission or 

distribution entity that does not have a common owner receives 

the electric energy. The facility also includes servicing 

inventory for such equipment that contains SF6 or PFCs.

Electric power transmission or distribution entity means

any entity that transmits, distributes, or supplies electricity 

to a consumer or other user, including any company, electric 

cooperative, public electric supply corporation, a similar 

Federal department (including the Bureau of Reclamation or the 
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Corps of Engineers), a municipally owned electric department 

offering service to the public, an electric public utility 

district, or a jointly owned electric supply project.

Operator, for the purposes of this subpart, means any 

person who operates or supervises a facility, excluding a person 

whose sole responsibility is to ensure reliability, balance load 

or otherwise address electricity flow.