EXHIBIT E

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580431 - 1 - 

ALJ/TIM/avs Date of Issuance 4/26/2012

 

Decision 12-04-024 April 19, 2012

BEFORE THE PUBLIC UTILITIES COMMISSION OF THE STATE OF CALIFORNIA 

Application of San Diego Gas & Electric 

Company for Review of its Proactive 

De-Energization Measures and Approval 

of Proposed Tariff Revisions (U902E). 

Application 08-12-021 

(Filed December 22, 2008) 

DECISION GRANTING PETITION TO MODIFY DECISION 09-09-030 

AND ADOPTING FIRE SAFETY REQUIREMENTS 

FOR SAN DIEGO GAS & ELECTRIC COMPANY 

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TABLE OF CONTENTS 

Title Page 

DECISION GRANTING PETITION TO MODIFY DECISION 09-09-030 

AND ADOPTING FIRE SAFETY REQUIREMENTS FOR 

SAN DIEGO GAS & ELECTRIC COMPANY .....................................................2

1. Summary of Decision..................................................................................................2

2. Background...................................................................................................................2

3. DisabRA’s Petition to Modify D.09-09-030 ..............................................................7

3.1. Summary of the Petition.................................................................................7

3.2. Summary of Responses to the Petition.........................................................7

3.2.1. CPSD and DRA ....................................................................................7

3.2.2. County of San Diego............................................................................7

3.2.3. MGRA....................................................................................................8

3.2.4. SCE .........................................................................................................8

3.2.5. SDG&E...................................................................................................8

3.3. Discussion .........................................................................................................9

4. Authority to Shut Off Power in Hazardous Wind Conditions...........................11

4.1. Introduction....................................................................................................11

4.2. Summary of GO 95 Requirements for Wind Loads..................................12

4.3. Summary of the Parties’ Positions ..............................................................15

4.3.1. The Communications Providers......................................................15

4.3.2. CPSD and DRA ..................................................................................15

4.3.3 MGRA...................................................................................................16

4.3.4. SCE .......................................................................................................17

4.3.5. SDG&E.................................................................................................20

4.4. Discussion .......................................................................................................24

4.4.1. SDG&E’s Design Standard for Wind Loads ..................................25

4.4.2. Shutting Off Power in Hazardous Wind Conditions ...................28

4.4.3. Design Requirements ........................................................................33

5. Comments on the Proposed Decision.....................................................................34

6. Assignment of the Proceeding.................................................................................34

Findings of Fact...............................................................................................................34

Conclusions of Law ........................................................................................................35

ORDER .............................................................................................................................36

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DECISION GRANTING PETITION TO MODIFY DECISION 09-09-030 

AND ADOPTING FIRE SAFETY REQUIREMENTS FOR 

SAN DIEGO GAS & ELECTRIC COMPANY 

1. Summary of Decision 

Today’s decision grants Disability Rights Advocates’ petition to modify 

Decision (D.) 09-09-030 to require San Diego Gas & Electric Company (SDG&E) 

to provide notice and mitigation, to the extent feasible and appropriate, 

whenever SDG&E shuts off power for public-safety reasons. 

Today’s decision also provides the following guidance regarding the 

Commission’s determination in D.09-09-030 that SDG&E has authority under 

California Public Utilities Code Section 451 and Section 399.2(a) to shut off power 

in order to protect public safety when strong Santa Ana winds exceed the design 

basis for SDG&E’s system and threaten to topple power lines onto tinder dry 

vegetation. First, today’s decision provides more details regarding the specific 

Santa Ana wind conditions that may trigger a power shut-off event. Second, 

today’s decision lists the factors the Commission may consider in determining if 

a decision by SDG&E to shut off power was reasonable and qualifies for an 

exemption from liability under SDG&E’s Electric Tariff Rule 14. 

2. Background 

Santa Ana winds are strong, dry winds that occur periodically in Southern 

California. In October 2007, Santa Ana winds swept across Southern California 

and caused dozens of wildfires. The conflagration burned 780 square miles, 

killed 17 people, and destroyed thousands of homes and buildings. Hundreds of 

thousands of people were evacuated at the height of the fires. Transportation 

was disrupted over a large area for several days, including many road closures. 

Portions of the electric power network, public communication systems, and 

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community water sources were destroyed. Several of the worst wildfires were 

reportedly ignited by power lines. These included the Grass Valley Fire 

(1,247 acres); the Malibu Canyon Fire (4,521 acres); the Rice Fire (9,472 acres); the 

Sedgewick Fire (710 acres); and the Guejito and Witch Fires (197,990 acres). The 

total area burned by these five power-line fires was more than 334 square miles.1

In response to the widespread devastation, San Diego Gas & Electric 

Company (SDG&E) filed Application (A.) 08-12-021 for authority to shut off 

electric power as a fire-prevention measure when Santa Ana winds reach a 

sustained speed of 35 miles per hour (mph) or wind gusts reach 55 mph 

accompanied by sustained winds of 30 mph. The Commission denied SDG&E’s 

application in Decision (D.) 09-09-030, finding that SDG&E had not 

demonstrated that the fire-prevention benefits from its plan to shut off power 

outweighed the significant costs, burdens, and risks imposed on customers and 

communities in areas where power is shut off. 

Importantly, D.09-09-030 distinguished between its denial of SDG&E’s 

application and SDG&E’s statutory authority under Pub. Util. Code § 451 and 

§ 399.2(a)2

 to shut off power in emergency situations: 

Our denial of SDG&E’s application does not affect SDG&E’s 

authority under § 451 and § 399.2(a) to shut off power in 

emergency situations when necessary to protect public 

safety... SDG&E’s statutory obligation [under § 451 and 

§ 399.2(a)] to operate its system safely requires SDG&E to shut 

 

1

 Decision 12-01-032 at 5 - 6. The Rice, Guejito, and Witch Fires were in SDG&E’s 

service territory. The Guejito and Witch Fires merged to become one fire. 

2

 All statutory references are denoted by the symbol “§” and refer to the California 

Public Utilities Code unless otherwise noted. 

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off its system if doing so is necessary to protect public safety. 

For example, there is no dispute that SDG&E may need to 

shut off power in order to protect public safety if Santa Ana 

winds exceed the design limits for SDG&E’s system and 

threaten to topple power lines onto tinder dry brush. 

(D.09-09-030 at 61 - 62.) 

The Commission concluded in D.09-09-030 that if SDG&E were to exercise 

its statutory authority to shut off power, the Commission could review SDG&E’s 

decision after the fact for reasonableness.3

Although D.09-09-030 denied SDG&E’s power shut-off plan, the decision 

encouraged SDG&E to develop and submit an improved shut-off plan. To this 

end, D.09-09-030 directed SDG&E to make a good-faith effort to develop a 

comprehensive fire-prevention program in collaboration with all stakeholders. 

The fire-prevention program had be based on a cost-benefit analysis that 

demonstrates (1) the program will result in a net reduction in wildfire ignitions, 

and (2) the benefits of the program outweigh any costs, burdens, or risks the 

program imposes on customers and communities. At the conclusion of the 

collaborative process, SDG&E was authorized to file an application for approval 

of the jointly developed fire-prevention program. If the collaborative process did 

not result in a consensus proposal, SDG&E was authorized to file an application 

containing its own proposed fire-prevention program.4

 

3 D.09-09-030 at 62. 

4

 D.09-09-030, Ordering Paragraphs 1 – 3. 

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As required by D.09-09-030, SDG&E initiated a collaborative process to 

develop a comprehensive fire-prevention program. One of participants was 

Disability Rights Advocates (DisabRA).5

On September 7, 2010, DisabRA filed a petition to modify D.09-09-030 

pursuant to Rule 16.4 of the Commission’s Rules of Practice and Procedure. The 

petition states that SDG&E informed the parties during the collaborative process 

that SDG&E intends to shut off power when strong winds exceeds the design 

basis for its utility poles and other factors (e.g., a declared Red Flag Warning) 

concurrently dictate such action. DisabRA’s petition seeks to modify D.09-09-030 

to require SDG&E to take appropriate and feasible steps to warn and protect its 

customers whenever it shuts off power pursuant to its statutory authority. 

Responses to DisabRA’s petition were filed by SDG&E, the County of 

San Diego, the Mussey Grade Road Alliance (MGRA), Southern California 

Edison Company (SCE), and jointly by the Commission’s Consumer Protection 

and Safety Division (CPSD) and Division of Ratepayer Advocates (DRA). 

DisabRA filed a reply on October 18, 2010. 

A key issue raised in the responses to DisabRA’s petition concerns the 

wind speed at which SDG&E may exercise its statutory authority to shut off 

power. Briefly, SCE and SDG&E assert that the Commission’s General Order 

(GO) 95 requires electric utilities to design overhead power-line facilities to 

 

5

 On September 8, 2011, the Center for Accessible Technology (CforAT) filed a motion 

for party status in this proceeding. The motion states that CforAT should replace 

DisabRA in this proceeding, and that DisabRA will cease to participate as an active 

party in this proceeding. The motion was granted in a ruling dated October 7, 2011. 

Today’s decision uses “DisabRA” to refer to both DisabRA and CforAT. 

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withstand a wind speed of 56 mph, and that electric utilities may exercise their 

statutory authority to shut off power when wind gusts exceed 56 mph.6 In 

contrast, CPSD and DRA contend that GO 95 requires overhead power-line 

facilities to withstand wind gusts of at least 91 mph, and that it would be 

unreasonable for SDG&E to shut off power at winds speeds below 91 mph. 

On June 3, 2011, the assigned Administrative Law Judge (ALJ) issued a 

ruling that directed SDG&E to file comments containing specified information 

about (1) the design of its overhead power-line facilities with respect to wind 

loads, and (2) the performance of its facilities in windy conditions. The other 

parties were also invited to file comments on these matters. 

Opening comments were filed on July 25, 2011, by CPSD, MGRA, SCE, 

SDG&E, and a coalition of Communications Providers.7 Reply comments were 

filed on August 12, 2011, by CPSD, MGRA, SCE, and SDG&E.8

 The parties were 

also provided an opportunity by the ALJ ruling dated June 3, 2011, to request an 

evidentiary hearing on wind-speed issues. There were no requests for an 

evidentiary hearing, and none was held. 

 

6 GO 95 specifies several different wind-load requirements. Today’s decision will use 

the wind-load requirements for overhead power-line facilities classified as Grade A 

and located in the Light-Loading District, unless otherwise indicated. 

7 The Communications Providers are several AT&T entities and affiliates; 

CoxCom, Inc. and Cox California Telcom, LLC; CTIA-The Wireless Association; 

Time Warner Cable; and the California Cable & Telecommunications Association. 

8

 MGRA filed amended comments and reply comments on September 2, 2011. CPSD 

filed amended reply comments on September 7, 2011. 

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3. DisabRA’s Petition to Modify D.09-09-030 

3.1. Summary of the Petition 

DisabRA represents that SDG&E has refused to commit to any plan for 

notifying customers when SDG&E anticipates that it will shut off power for 

safety reasons pursuant to its statutory authority, or for helping customers to 

cope with statutory shut offs by providing shelter, evacuation assistance, 

generators, or financial assistance. 

DisabRA is concerned that shutting off power without notice or mitigation 

will place SDG&E’s residential customers at serious risk, especially those with 

disabilities. To ensure that the public is protected in the event of a statutory 

shut off, DisabRA asks the Commission to modify D.09-09-030 to (1) require 

SDG&E to take appropriate and feasible steps to warn and protect its customers 

whenever SDG&E shuts off power pursuant to its statutory authority; and 

(2) state that the Commission’s after-the-fact review of a statutory shut-off may 

assess the adequacy of the notice and mitigation provided by SDG&E. 

3.2. Summary of Responses to the Petition 

3.2.1. CPSD and DRA 

CPSD and DRA support DisabRA’s petition to modify D.09-09-030. CPSD 

and DRA argue that shutting off power without sufficient mitigation would be 

contrary to D.09-09-030, which rejected SDG&E’s proposed shut-off plan because 

it would, on balance, do more harm than good. 

3.2.2. County of San Diego 

The County of San Diego supports DisabRA’s petition. The County 

believes that granting the petition will provide an incentive for SDG&E to 

implement reasonable mitigation requests from stakeholders, and also prevent 

SDG&E from shifting all costs for an outage to SDG&E’s customers, even though 

some of these costs are more cost-effectively borne by SDG&E. 

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3.2.3. MGRA 

MGRA supports DisabRA’s petition. At the same time, MGRA agrees 

with the general principle that it may be prudent to shut off power to prevent 

power-line fire ignitions during extreme weather conditions. 

3.2.4. SCE 

SCE opposes DisabRA’s petition because it could adversely affect SCE’s 

ability to respond to emergencies. Although SCE has no plans to shut off power 

based on pre-defined weather conditions, SCE does de-energize circuits when 

necessary for public safety. For example, SCE will shut off power when debris 

hits a power line during a wind storm, vegetation contacts a power line, or a 

power line is down for any reason (e.g., pole hit by a vehicle). In situations like 

these, SCE endeavors to notify customers, but SCE says it has no obligation to do 

so if emergency conditions require an immediate shut-off. Mitigation for all 

outages, whatever the cause, is addressed by SCE’s Service Guarantee Program, 

which applies when an unplanned outage exceeds 24 hours. 

SCE is concerned that a requirement to notify customers prior to 

de-energizing a power line would take precedence over public safety. SCE 

opines that uncertainty about whether a condition is “dangerous enough” to 

permit immediate shut-off without customer notification, and to what extent the 

utility must implement mitigation beyond its service guarantee, should not be 

occupying the minds of utility decision-makers during emergency situations. 

3.2.5. SDG&E 

SDG&E opposes DisabRA’s petition to modify D.09-09-030. SDG&E 

argues that the petition is unnecessary because SDG&E is implicitly obligated by 

§§ 399.2 and 451 to provide customer notification and other mitigation when 

feasible and appropriate. For public-safety outages, SDG&E will provide a 

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pre-recorded telephone notice to the general population, and additional personal 

notification to medical baseline customers, life support customers, and assigned 

commercial accounts. SDG&E’s notification system includes text capability to 

reach those with hearing disabilities. SDG&E will also implement mitigation 

measures when emergency conditions require SDG&E to shut off power. 

SDG&E contends that to the extent DisabRA’s petition is interpreted as a 

proposal for a new and higher standard, the proposal should be rejected for three 

reasons. First, the standard is vague. The petition does not identify any specific 

notice or mitigations requirements. 

Second, the petition does not address the potential conflict between the 

existing public-safety obligation and a new standard for customer notification 

and mitigation. Imposing a new imperative without identifying its precise 

requirements or how it interacts with existing obligations may result in 

unintended negative consequences that undermine public safety. 

Finally, to the extent DisabRA seeks to require SDG&E to implement the 

mitigation measures proposed by SDG&E in A.08-12-021, the petition does not 

address the feasibility of those mitigation measures in the context of a statutory 

shutoff event. SDG&E’s application involved a proactive shut-off plan, whereas 

a statutory shutoff event is reactive and applies only where conditions threaten 

immediate harm to SDG&E’s system. It may not be possible to implement the 

mitigation measures proposed in A.08-12-021 in every emergency situation. 

3.3. Discussion 

In D.09-09-030, the Commission held that SDG&E has authority under 

§ 399.2 and § 451 to shut off power during emergencies when necessary to 

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protect public safety.9

 DisabRA seeks to modify D.09-09-030 to require SDG&E 

to take all feasible and appropriate steps to (1) notify customers of statutory 

shutoff events, and (2) mitigate the costs and risks that statutory shutoff events 

impose on customers. DisabRA also seeks to modify D.09-09-030 to state that the 

Commission’s review of a statutory shutoff event may assess the adequacy of the 

notice and mitigation provided by SDG&E. The Commission has broad 

jurisdiction under the California Constitution and the Public Utilities Code to 

grant or deny DisabRA’s petition.10

SDG&E acknowledges that it is implicitly obligated by § 399.2 and § 451 to 

provide notice and mitigation, to the extent feasible and appropriate, whenever 

its shuts off power.11 Therefore, we conclude that it is reasonable to adopt 

DisabRA’s petition to modify D.09-09-030, as doing so merely formalizes an 

existing requirement. 

It is not possible to anticipate every emergency situation where power may 

be shut off for safety reasons and then specify the exact notice and mitigation 

measures that should be implemented in each situation. In general, SDG&E 

should provide as much notice as feasible before shutting off power so the 

affected providers of essential services (e.g., schools, hospitals, prisons, public 

safety agencies, telecommunications utilities, and water districts) and customers 

who are especially vulnerable to power interruptions (e.g., customers who rely 

on medical life-support equipment) may implement their own emergency plans. 

 

9 D.09-09-030, Conclusion of Law 3. 

10 California Constitution Article XII, §§ 3 and 6, and Pub. Util. Code §§ 216, 701, 

761-770, 8037, and 8056. 

11 SDG&E Response at 2 – 3. 

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Once power is shut off, SDG&E should focus its resources on restoring power as 

soon as possible. Any remaining resources should be concentrated on providing 

other mitigation to the extent feasible and appropriate under the circumstances. 

4. Authority to Shut Off Power in Hazardous Wind Conditions 

4.1. Introduction 

In D.09-09-030, the Commission held that SDG&E has authority pursuant 

to § 451 and § 399.2(a) to shut off power, if necessary to protect public safety, 

when strong Santa Ana winds threaten to topple power lines onto tinder dry 

brush.12 SDG&E subsequently informed DisabRA that most of SDG&E’s 

overhead power lines are designed to withstand wind gusts of 56 mph, and that 

SDG&E may shut off power as a safety precaution when wind gusts exceed 

56 mph. This prompted DisabRA to file its petition to modify D.09-09-030, which 

we addressed above in today’s decision. 

In their joint response to DisabRA’s petition, CPSD and DRA raised the 

corollary issue of SDG&E’s authority to shut off power when wind speeds 

exceed 56 mph. CPSD and DRA argue that GO 95 requires SDG&E’s system to 

withstand a wind speed of at least 91 mph, and that SDG&E would be in 

violation of D.09-09-030 and GO 95 if it shut off power below 91 mph. We 

conclude that SDG&E’s authority to shut off power at wind speeds between 

56 mph and 91 mph has a clear nexus with DisabRA’s petition and, therefore, 

should be addressed by today’s decision. 

 

12 D.09-09-030 at 61 - 62. 

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4.2. Summary of GO 95 Requirements for Wind Loads 

To better understand the positions of the parties, summarized below, we 

first review GO 95 requirements for wind loads. Rule 43 of GO 95 divides 

California into a Heavy-Loading District and a Light-Loading District. The 

Light-Loading District is all parts of California where the elevation is 3,000 feet 

or less. Rule 43.2(A) requires power-line facilities in the Light-Loading District 

with cylindrical surfaces (e.g., utility poles) to withstand a horizontal wind 

pressure of 8 pounds per square foot (psf). Facilities with flat surfaces (e.g., 

crossarms) must withstand a horizontal wind load of 13 psf. Approximately 90% 

of SDG&E’s overhead power-line facilities are in the Light-Loading District. 

Rule 44 prescribes an initial safety factor13 for each power-line element 

(e.g., poles and crossarms) at the time of installation that can vary based on the 

material (e.g., wood or metal) and the grade of construction. Most of SDG&E’s 

power-line facilities are Grade A or Grade B construction.14 Rule 44.3 allows the 

safety factor to degrade over time, but not below a safety factor of one or 

two-thirds of the safety factor at the time of installation, whichever is higher, at 

which time the facility must be reconstructed or replaced. 

Rule 48 requires overhead power-line facilities to be designed and 

constructed so they “will not fail” at a wind force equal to the wind load 

 

13 Rule 44 defines “safety factors” as “the minimum allowable ratios of ultimate 

strengths of materials to the maximum working stresses.” 

14 The grades of construction are A, B, C and F, with “A” being the highest. Utility 

poles with both power lines and communications lines attached must be Grade A. 

Utility poles with only distribution-level power lines attached may be Grade B. 

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specified in Rule 43 multiplied by the applicable safety factor in Rule 44. Rule 48 

states, in relevant part, as follows: 

Structural members and their connection shall be designed 

and constructed so that the structures and parts thereof will 

not fail or be seriously distorted at any load less than their 

maximum working loads ... specified in Rule 43 ... multiplied 

by the safety factor specified in Rule 44. (Emphasis added.) 

The following Table 1 shows the minimum wind loads (in psf and mph)15

that must be used for the design and construction of certain Grade A facilities in 

the Light-Loading District pursuant to Rules 43, 44, and 48: 

Table 1 

GO 95 Wind Load Requirements for the Light-Loading District 

Selected Grade A Power-Line Elements 

Rule 43.2(A) Rule 44.1 Rule 44.3 

Rule 48 

Working Load x Safety Factor

Line 

Element 

Working 

Load 

A 

Initial Safety 

Factor 

B 

Replacement 

Safety Factor 

C 

Initial 

A x B 

Replacement

A x C 

Wood Pole 8 psf 

56 mph 4 2.67 32 psf 112 mph

21.3 psf 

91 mph

Steel Pole 8 psf 

56 mph 1.5 1.0 12 psf 69 mph

8 psf 

56 mph

Wood Crossarm 

(flat surface) 

13 psf 

71 mph 2 1.33 26 psf 101 mph

17.33 psf 

82 mph

Steel Crossarm 

(flat surface) 

13 psf 

71 mph 1.5 1.0 19.5 psf 87 mph

13 psf 

71 mph

 

15 Today’s decision assumes that the relationship between wind load in psf and wind 

velocity (V) in mph is given by the equation: Wind load (psf) = 0.00256V2. The 

values for mph used by today’s decision are rounded to the nearest whole number. 

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The following Table 2 shows the minimum wind loads (in psf and mph) 

that must be used for the design and construction of certain Grade B facilities in 

the Light-Loading District pursuant to Rules 43, 44, and 48: 

Table 2 

GO 95 Wind Load Requirements for the Light-Loading District 

Selected Grade B Power-Line Elements 

Rule 43.2(A) Rule 44.1 Rule 44.3 

Rule 48 

Working Load x Safety Factor

Line 

Element 

Working 

Load 

A 

Initial Safety 

Factor 

B 

Replacement 

Safety Factor 

C 

Initial 

A x B 

Replacement

A x C 

Wood Pole 8 psf 

56 mph 3 2.0 24 psf 97 mph

16 psf 

79 mph

Steel Pole 8 psf 

56 mph 1.25 1.0 10 psf 63 mph

8 psf 

56 mph

Wood Crossarm 

(flat surface) 

13 psf 

71 mph 2 1.33 26 psf 101 mph

17.3 psf 

82 mph

Steel Crossarm 

(flat surface) 

13 psf 

71 mph 1.25 1.0 16.3 psf 80 mph

13 psf 

71 mph

Table 1 shows that Rule 48 requires a Grade A wood pole in the 

Light-Loading District to be designed so it “will not fail” at a wind speed of 

112 mph at the time of installation, and that a Grade A wood pole must be 

replaced when it no longer meets the “will not fail” standard at a wind speed of 

91 mph due to age-related deterioration or other causes. 

Similarly, Table 2 shows that Rule 48 requires a Grade B wood pole in the 

Light-Loading District to be designed so it “will not fail” at a wind speed of 

97 mph at the time installation, and that a Grade B wood pole must be replaced 

when it no longer meets the “will not fail” standard at a wind speed of 79 mph 

due to age-related deterioration or other causes. 

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Although Rule 48 establishes an explicit “will not fail” standard, other 

provisions in GO 95 appear to implicitly recognize that wood utility poles are not 

failsafe in severe wind conditions. These other provisions are briefly described 

below in the summary of SCE’s and SDG&E’s positions. 

4.3. Summary of the Parties’ Positions 

4.3.1. The Communications Providers 

The Communications Providers maintain that SDG&E’s statutory 

authority to shut off power in windy conditions cannot be based on wind speed 

alone. Each situation must be assessed to determine if public safety is better 

served by leaving power on, or shutting it off. Other factors besides wind 

conditions may be relevant, such as whether a Red Flag Warning is in effect. 

4.3.2. CPSD and DRA 

CPSD and DRA assert that Rule 48 requires SDG&E to design and 

construct overhead power-line facilities that “will not fail” at the wind speeds 

listed in the last column in Tables 1 and 2 above. For example, Table 1 shows 

that a Grade A wood pole must withstand a wind speed of at least 91 mph 

without failure. CPSD and DRA argue that it is unreasonable for SDG&E to shut 

off power at 56 mph because this is far below what is required by GO 95. 

CPSD acknowledges that the strength of wood poles can vary. In fact, 

CPSD provided several graphs and tables that show the probability that wood 

poles will fail at various wind speeds based on the specifications for wood poles 

in GO 95, Rule 48.1, Table 5, Footnote C. CPSD states that although the strength 

of wood pole varies, that has no effect on the Rule 48 requirement that Grade A 

wood poles “will not fail” at a wind speed of 91 mph. 

CPSD does not believe the data presented by SDG&E, summarized below, 

demonstrates that SDG&E should shut off power when wind speeds exceed 

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56 mph. Even though SDG&E identified almost 1,000 power-line failures and 

13 power-line fires attributable to strong winds, CPSD opines that many of these 

incidents may have been caused by noncompliance with GO 95. 

CPSD contends that the Commission is not limited to the options of either 

keeping power on and risking catastrophic power-line fires, or shutting off 

power when wind speeds exceed 56 mph. There are other measures that can be 

taken to reduce the risk of power-line fires. For example, SDG&E has modified 

its automatic re-closers so that SDG&E will no longer re-energize power lines 

automatically after a re-closer shuts off power to a circuit during a high-wind 

event. Instead, SDG&E will inspect its facilities to determine if electric power 

can be restored safely. CPSD believes this measure alone might have prevented 

the devastating Witch Fire in 2007. 

4.3.3 MGRA 

MGRA states that SDG&E is required to provide safe and reliable electric 

service in conditions typically found in its service area. SDG&E’s service area is 

dense with flammable vegetation and regularly experiences strong winds during 

dry conditions. MGRA submits that an infrastructure which even occasionally 

ignites fires in these conditions is not suitably robust and safe. 

MGRA agrees with the Commission’s conclusion in D.09-09-030 that there 

are weather conditions when the risk of power-line fires outweighs other 

considerations and justifies shutting off power. MGRA further notes that 

SDG&E’s comments establish that power-line failures and fires can occur when 

wind gusts exceed 56 mph. If this does not comply with GO 95, MGRA 

recommends that the Commission establish a remediation plan to have SDG&E’s 

system brought up to the correct standard over time. 

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4.3.4. SCE 

SCE interprets GO 95 as requiring overhead power lines to withstand the 

wind loads specified in Rule 43. For facilities with a cylindrical surface in the 

Light-Loading District, Rule 43.2(A) sets a requirement of 8 psf, which equates to 

a wind speed of 56 mph. The purpose of the safety factor required by Rule 44 

and Rule 48, according to SCE, is to ensure that facilities are built stronger than 

necessary for the design load of 56 mph established by Rule 43. 

SCE states that one reason Rules 44 and 48 require overhead power-line 

facilities to be built stronger than necessary is the inherent variability of 

materials. In the case of wood poles, Rule 48.1, Table 5, lists the strength for 

several species of wood. For example, the strength of Douglas Fir poles is 

8,000 pounds per square inch (psi) with a coefficient of variation (COV) of 0.20. 

Multiplying 8,000 psi by a COV of 0.20 gives a standard deviation of 1,600. Thus, 

the strength of 68% of Douglas Fir poles is between 6,400 psi and 9,600 psi, and 

the strength of 95% of Douglas Fir poles is between 4,800 psi and 11,200 psi. 

A Douglas Fir pole can be anywhere in this range and comply with GO 95. 

SCE explains that because there is wide variability in the strength of wood 

poles, Rule 44 requires new Grade A wood poles to have a safety factor of 4.0 to 

protect against the structural failure of wood poles. In contrast, the required 

safety factor for new Grade A steel poles is only 1.5 because the variability of 

material strength for steel poles is much less (i.e., the COV is smaller). 

To illustrate the variability of wood poles, SCE calculated an estimated rate 

of pole failures at various wind speeds. Assuming a sufficiently large sample of 

new Grade A wood poles in the Light-Loading District that are fully loaded, 

identically installed, and identically exposed to wind velocities, approximately 

0.01% of all such poles will fail at a wind speed of 56 mph. These rare failures 

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will occur simply because the actual strength of the failed poles will be far below 

the assumed average strength of 8,000 psi. 

SCE represents that as wind speeds increase, the statistical probability of 

pole failures will rise. Using the same assumptions as above, 0.02% of new 

Grade A wood poles could be expected to fail at 60 mph, 0.10% at 70 mph, 13.7% 

at 100 mph, and 50% at 112 mph. SCE cautions that the actual frequency of pole 

failures should be less than calculated because (1) many poles are not loaded to 

their maximum GO 95 capacity, (2) wind does not impose an equal load on all 

poles at all times, and (3) wind usually blows at other than the 90°angle assumed 

in GO 95. 

SCE notes that although Rule 44 requires a higher safety factor for wood 

poles relative to most facilities attached to the poles (e.g., crossarms), there is no 

reason to expect that the facilities attached to wood poles will fail at lower wind 

speeds than the poles themselves. SCE agrees with SDG&E that the pole, rather 

than the components attached to it, should fail first due to wind-related loads.16

 

16 SDG&E Opening Comments at 103. 

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With respect to a utility’s decision to shut off power in hazardous weather 

conditions, SCE states that power-line facilities should not be operated to within 

a hair’s breadth of their theoretical failure point. It is impossible to know when 

the actual failure point will be reached for any particular structure because: 

• Wind speed is variable from moment to moment. It is not 

feasible to shut off power at the precise moment when 

wind speed exceeds the design limit of overhead 

power-line facilities. 

• Wind speed is variable from place to place. It is impossible 

to know the wind speed everywhere on the system. As 

wind speed approaches the design limit at a location on the 

system where wind speed is measured, it is possible that 

wind speeds are exceeding the design limit elsewhere on 

the system where wind speed is not measured. 

• The strength of wood is inherently variable. There is a 

statistical possibility that a particular wood pole or 

crossarm will fail before the design limit is reached. 

SCE identifies several other factors that should be considered when 

deciding whether to shut off power due to a potential fire hazard. These include 

the number of customers affected, possible fire damage, fire-suppression 

resources, and weather conditions (e.g., wind, temperature, and humidity). 

SCE opines that it is not practical to develop rules for when it will always 

be appropriate to shut off power given the many factors and uncertainties that 

affect a utility’s decision to shut off power. Thus, shutting off power must 

remain a discretionary decision for the utility based on the utility’s knowledge, 

expertise, and contemporaneous conditions on its system. 

SCE disagrees with CPSD and DRA’s “never fail” interpretation of Rule 48. 

Their interpretation would require utilities to construct their facilities to a new 

and higher standard that would cost billions of dollars. For example, utilities 

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would have to install many more poles than presently, and replace existing poles 

with larger poles. SCE believes that such changes are unwarranted because there 

is no showing that the utilities’ long-standing interpretation of GO 95 has 

resulted in an unacceptable rate of pole failures. 

4.3.5. SDG&E 

SDG&E joins SCE in disagreeing with CPSD and DRA’s interpretation of 

Rule 48 as requiring that Grade A wood poles “will not fail” at wind speeds 

below 91 mph. SDG&E argues that Rule 43 establishes the design standard for 

wind loads, not Rule 48. SDG&E posits that the Rule 43 wind speeds which 

facilities must withstand are listed in Column A of Tables 1 and 2 above. For 

example, Column A of Table 1 shows that Grade A poles must withstand wind 

gusts of 56 mph. 

SDG&E avers that the purpose of the safety factor required by Rule 44 and 

Rule 48 is to ensure that power-line facilities are built stronger than necessary for 

the design loads specified in Rule 43, consistent with sound engineering 

principles. The adoption of CPSD and DRA’s interpretation of Rule 48 as 

establishing the design loads, and not Rule 43, would force a major change in the 

way California utilities design their systems. 

SDG&E provided extensive information regarding the performance of its 

overhead power-line facilities in windy conditions. Table 1 of SDG&E’s 

comments lists every known incident from January 1, 2000 to mid-2011 where an 

electrical or structural failure occurred on SDG&E’s system which SDG&E 

attributes to strong winds. SDG&E’s Table 1 lists a total of 969 failures. Most 

failures were electrical failures. Pole failures, which include failures of poles, 

crossarms, guys, insulators, and braces, comprise less than 10% of the incidents 

reported in SDG&E’s Table 1. 

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SDG&E’s Table 2 lists every known incident from January 1, 2000 to 

mid-2011 where a wind-related failure of SDG&E’s overhead power-line facilities 

may have ignited a fire, although fault may yet to be determined. The 

approximate size of the fire and any damage caused by the fire are also provided. 

SDG&E lists a total of 13 fires, including the Witch, Rice, and Guejito Fires in 

October 2007, which together burned more than 207,000 acres. 

SDG&E’s Table 3 lists every incident from January 1, 2000 to mid-2011 for 

which SDG&E has records where an anemometer reported a wind speed of at 

least 56 mph. Table 3 includes the date, location, start time, length of time above 

56 mph, and the maximum measured wind speed for each incident. 

SDG&E’s Table 4 shows that most wind-related failures occurred on a 

small number of days with strong winds. In particular, there were seven severe 

wind events encompassing 12 days that accounted for 53% of all wind-related 

failures during the period of January 1, 2000 through mid-2011.17 SDG&E’s 

Table 5 shows that most of the severe wind events and associated failures listed 

in Table 4 occurred when the fire threat was extremely high. 

SDG&E also provided information regarding the design of its overhead 

power-line facilities. SDG&E states that it has 8,431 miles of overhead powerline facilities, all of which comply with GO 95. SDG&E represents that 90% of its 

overhead facilities (approximately 7,552 miles) are in the Light-Loading District 

defined by Rule 43.2 and are designed to withstand a wind speed of 56 mph. 

Approximately 9% of SDG&E’s overhead facilities (762 miles) are in the 

Heavy-Loading Districts defined by Rule 43.1 and are designed to withstand a 

 

17 SDG&E’s Table 4 shows a total of 521 failures during the 12 days listed in Table 4. 

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wind speed of 48 mph. Approximately 1% of SDG&E’s overhead facilities 

(90 miles) are designed to withstand a wind speed of 85 mph pursuant to 

National Electric Safety Code Rule 250C. 

As noted previously, 90% of SDG&E’s overhead power-line facilities are 

designed to withstand a wind speed of 56 mph. For these facilities, the rate of 

failure is very low at wind speeds below 56 mph, but rises sharply when wind 

gusts reach and exceed the design basis of 56 mph. 

SDG&E explains that GO 95 recognizes that wood utility poles do not have 

uniform strength. In particular, Rule 48.1, Table 5 (Wood Strengths) specifies 

average strengths for wood poles, with 50% of wood poles stronger than the 

values listed in Rule 48.1, Table 5, and 50% weaker. 

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For Douglas Fir poles and Southern Yellow Pine poles, Rule 48.1, Table 5, 

specifies a modulus of rupture18 of 8,000 psi for poles that comply with American 

National Standards Institute (2002) standard O5.1 (ANSI O5.1). SDG&E states 

that all of its wood poles meet ANSI 05.1. SDG&E represents that ANSI 05.1 

indicates that the COV for the modulus of rupture (MOR) is 0.20 (or 20%). The 

mean value of 8,000 psi, coupled with a COV of 20%, defines a normal 

distribution for the strength of wood poles shown in the following Figure 5 of 

SDG&E’s comments: 

Normal Distribution Curve - Strength of Full-Size Wood Poles 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0

0.00005

0.0001

0.00015

0.0002

0.00025

0.0003

0 5000 10000 15000 20000

Cumulative Probability

Probability Density

Modulus of Rupture (psi)

 

18 Modulus of rupture is the breaking point for a material subjected to a bending force. 

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Based on the assumed strength distribution for wood poles in the above 

graph, SDG&E’s Table 6 provided the estimated failure rates for fully loaded 

Grade A wood poles and Grade B wood poles at various wind speeds. 

The estimated failure rates in SDG&E’s Table 6 are a worst-case scenario in 

that it assumes all of SDG&E’s poles are loaded to the maximum allowed by 

GO 95. However, SDG&E’s wood poles are typically loaded at 70% to 80% of the 

maximum allowed by GO 95 at the time of installation, and SDG&E’s installed 

poles have an average remaining strength of 95%. SDG&E’s Tables 7 and 8 show 

the estimated failure rates at various wind speeds for wood poles with 70% 

utilization and 5% degradation, and 80% utilization and 5% degradation. 

In terms of operating its overhead power-line system, SDG&E will not 

shut off power based on wind conditions alone. SDG&E will consider all 

relevant circumstances, including concurrent temperature, humidity, and 

vegetation moisture. If SDG&E does shut off power, SDG&E will restore power 

when the conditions that created the public-safety hazard have abated. This 

comports with SDG&E’s operating practices with respect to all power outages. 

4.4. Discussion 

In D.09-09-030, the Commission held that SDG&E has statutory under 

§ 451 and § 399.2(a) to shut off power in emergency situations when necessary to 

protect public safety. These laws state, in relevant part, as follows: 

§ 451: Every public utility shall furnish and maintain such 

adequate, efficient, just, and reasonable service, 

instrumentalities, equipment, and facilities...as are necessary 

to promote the safety, health, comfort, and convenience of its 

patrons, employees, and the public. 

§ 399.2 (a)(1): It is the policy of this state, and the intent of the 

Legislature, to reaffirm that each electrical corporation shall 

continue to operate its electric distribution grid in its service 

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territory and shall do so in a safe, reliable, efficient, and 

cost-effective manner. 

§ 399.2 (a)(2): In furtherance of this policy, it is the intent of 

the Legislature that each electrical corporation shall continue 

to be responsible for operating its own electric distribution 

grid including, but not limited to, owning, controlling, 

operating, managing, maintaining, planning, engineering, 

designing, and constructing its own electric distribution grid, 

emergency response and restoration, service connections, 

service turnons and turnoffs, and service inquiries relating to 

the operation of its electric distribution grid, subject to the 

commission's authority. 

We affirm our holding in D.09-09-030 that SDG&E’s statutory obligation to 

operate its system safely requires SDG&E to shut off its system if doing so is 

necessary to protect public safety. We also affirm our determination in 

D.09-09-030 that SDG&E may need to shut off power to protect public safety if 

strong Santa Ana winds threaten to topple power lines onto tinder dry brush. 

4.4.1. SDG&E’s Design Standard for Wind Loads 

We next consider the design of SDG&E’s power-line facilities with respect 

to wind loads. As a general rule, utility poles are more likely to break due to 

strong winds than other power-line components.19 Therefore, today’s decision 

will focus on utility poles. 

Most of SDG&E’s Grade A and Grade B wood poles are in the LightLoading District. SDG&E provided extensive and uncontroverted comments 

that show its Grade A and Grade B wood poles in the Light-Loading District are 

designed to withstand wind gusts of 56 mph. As a result, SDG&E’s Grade A and 

 

19 SDG&E Opening Comments at 103. 

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Grade B wood poles rarely fail at wind gusts below 56 mph. However, when 

wind gusts exceed SDG&E’s design basis of 56 mph, the rate of pole failures 

increases markedly. 

The following Table 3 reproduces SDG&E’s estimated failure rates for its 

Grade A and Grade B wood poles, assuming new poles are loaded at 70% or 80% 

of the maximum capacity allowed by GO 95, and aged poles have 95% of their 

remaining strength. 

Table 3 

Estimated Failure Rates for SDG&E’s Wood Poles from Strong Winds 

For New Poles (100% remaining strength) and Aged Poles (95% remaining strength) 

Grade A Wood Poles Grade B Wood Poles 

Wind 

Speed 

(mph) 

New 

70% 

Utilized 

Aged 

70% 

Utilized 

New 

80% 

Utilized

Aged 

80% 

Utilized 

New 

70% 

Utilized

Aged 

70% 

Utilized 

New 

80% 

Utilized

Aged 

80% 

Utilized

60 0.0030% 0.0037% 0.0054% 0.0068% 0.0113% 0.0149% 0.0233% 0.0313%

70 0.0126% 0.0166% 0.0262% 0.0353% 0.0656% 0.0907% 0.1551% 0.2180%

80 0.0577% 0.0796% 0.1350% 0.1898% 0.3835% 0.5485% 0.9841% 1.4166%

90 0.2683% 0.3813% 0.6788% 0.9761% 2.0336% 2.9336% 5.2135% 7.3963%

100 1.174% 1.695% 3.044% 2.116% 8.789% 12.267% 20.249% 26.966%

110 4.545% 6.469% 11.149% 15.394% 27.797% 36.094% 51.675% 62.094%

120 14.395% 19.630% 30.854% 39.630% 59.871% 70.050% 84.135% 90.585%

Source: SDG&E Opening Comments at 110 – 11, Tables 7 and 8.

Table 3 represents the “as built” condition of SDG&E’s Grade A and 

Grade B wood poles, and denotes the lower and upper bounds for most of 

SDG&E’s wood poles. Table 3 shows that SDG&E’s Grade A wood poles will fail 

at an estimated rate of 30 to 68 poles per million at 60 mph, 126 to 353 poles per 

million at 70 mph, and so on. Similarly, Table 3 shows that SDG&E’s Grade B 

wood poles will fail at an estimated rate of 113 to 313 poles per million at 

60 mph, 656 to 2,180 poles per million at 70 mph, and so on. 

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In reality, SDG&E’s wood poles will probably fail at a lower rate than 

estimated in Table 3 for the following reasons: 

• Table 3 assumes the wind is blowing at a 90-degree angle 

relative to the structure, which imposes the maximum wind 

load on the structure. Wind that hits a structure at a 

90-degree angle imposes twice the load compared to a 

30-degree angle. Although wind often blows at a 90-degree 

angle relative to a vertical utility pole with a cylindrical 

surface, the wind angle is typically less than 90 degrees for 

most facilities attached to a utility pole, such as crossarms and 

conductors (which transfer their wind loads to the utility 

poles to which they are attached). 

• The drag coefficients used in calculations to determine the 

wind load for cylindrical surfaces are assumed to be 1.0 for 

conservatism. However, the actual coefficients are usually 

less than 1.0, especially at higher wind speeds. Thus, the real 

wind loads on utility poles are typically lower than calculated. 

• Poles are interconnected by wires and share wind loads. 

• The estimated failure rates in Table 3 assume the utility poles 

are Douglas Fir or Southern Pine with an average MOR of 

8,000 psi and a COV of 0.20. However, all of SDG&E’s wood 

poles comply with ANSI 05.1-1992.20 Appendix C, Table C.1, of 

ANSI 05.1-1992 shows that for wood poles with a length of 

50 feet of less, Coastal Douglas Fir poles have an MOR of 

9,620 psi with a COV of 0.135; Interior Douglas Fir poles have 

an MOR of 8,020 psi with a COV of 0.179; and Southern Pine 

poles have an MOR of 10,190 psi with a COV of 0.169.21 

Consequently, many poles installed by SDG&E are stronger 

than assumed in Table 3. 

 

20 SDG&E Opening Comments at 107. 

21 We take official notice of ANSI 05.1-1992 pursuant §§ 701 and 1701, and Rule 13.9 of 

the Commission’s Rules of Practice and Procedure. 

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Although Table 3 likely overstates the risk that SDG&E’s wood poles will 

fail due to strong winds, there is a clearly a risk that SDG&E’s existing wood 

poles may fail when winds exceed 56 mph, with the risk increasing exponentially 

with wind speed. This risk is described quantitatively by the engineering 

calculations that are tabulated in SDG&E’s comments,22 and evidenced by the 

dozens of SDG&E poles that have failed over the years during strong winds.23

We are not persuaded by CPSD’s argument that most failures of SDG&E’s 

overhead power-line facilities during strong winds may be due to substandard 

facilities. Although we do not discount the possibility of some substandard 

facilities, SDG&E’s comments show there is a real and quantifiable risk that 

existing facilities which are not substandard (according to SDG&E) will fail when 

exposed to strong winds. 

4.4.2. Shutting Off Power in Hazardous Wind Conditions 

The failure of SDG&E’s overhead power-line facilities during strong 

Santa Ana winds poses a significant fire hazard and threat to public safety. 

SDG&E’s comments show that during the period of January 1, 2000 through 

mid-2011, there were two instances where strong Santa Ana winds occurred 

simultaneously with a Red Flag Warning declared by the National Weather 

Service. During these two Santa Ana wind events, there were 149 failures of 

SDG&E’s overhead power-line facilities, including 16 pole failures, which 

 

22 SDG&E Opening Comments, Tables 6, 7 and 8 at 109 – 111. (See also SCE’s Opening 

Comments at 8 – 9, and CPSD’s Opening Comments at 13 – 17.) 

23 SDG&E Opening Comments, Table 1 at 4 – 79, and Table 4 at 98. 

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purportedly ignited three wildfires.24 These three fires together burned more 

than 207,000 acres (323 square miles) and caused widespread devastation.25

In D.09-09-030, the Commission held that SDG&E has statutory authority 

under § 451 and § 399.2(a) to shut off power to protect public safety if Santa Ana 

winds exceed the design basis for SDG&E’s system and threaten to topple power 

lines onto tinder dry brush. The record of this proceeding establishes that 

SDG&E will likely face the situation where strong Santa Ana winds exceed 

SDG&E’s design basis of 56 mph for its overhead power-line facilities, presenting 

SDG&E with the dilemma of keeping vital power flowing in a dangerous 

situation, or shutting off power to protect the public from potentially 

catastrophic wildfires ignited by wind-damaged power-line facilities. 

SDG&E will be in the best position to determine when power should be 

shut off to protect public safety. Only SDG&E has the detailed knowledge of its 

facilities that is needed to make this decision in real time based on 

contemporaneous local weather conditions. 

As a general principle, SDG&E should keep power flowing when wind 

speeds exceed 56 mph. Without power, numerous unsafe conditions can occur. 

Traffic signals do not work, medical life support equipment does not work, water 

pumps do not work, and communication systems do not work. As the California 

Legislature recognized in § 330(g), “[r]eliable electric service is of utmost 

importance to the safety, health, and welfare of the state’s citizenry and 

 

24 SDG&E Opening Comments, Table 1 at 5 – 12 and 50 – 54. The three fires were the 

Rice, Guejito, and Witch Fires. 

25 SDG&E Opening Comments, Table 2 at 89, and Table 4 at 98. Today’s decision does 

not find that SDG&E’s power-line facilities did, in fact, ignite fires. 

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economy.” Consequently, SDG&E should shut off power only as a last resort, 

and only when SDG&E is convinced there is a significant risk that strong 

Santa Ana winds will topple power lines onto flammable vegetation. This is 

consistent with SDG&E’s Commission-approved tariffs, which acknowledge that 

SDG&E has an obligation to provide electrical service on a continuous basis.26 

Any decision by SDG&E to shut off power under its statutory authority 

may be reviewed by the Commission pursuant to its broad jurisdiction over 

matters regarding the safety of public utility operations and facilities. The 

Commission may decide at that time whether SDG&E’s decision to shut off 

power was reasonable and qualifies for an exemption from liability under 

SDG&E’s Electric Tariff Rule 14. This tariff rule provides that SDG&E will not be 

held liable for an interruption in service “caused by inevitable accident, act of 

God, fire, strikes, riots, war or any other cause not within its control.”27

In assessing whether SDG&E’s decision to shut off power was reasonable 

and should be exempt from liability under Tariff Rule 14, we may consider the 

following factors. First, there is a strong presumption that power should remain 

on for public safety reasons.28 SDG&E will have the burden of demonstrating 

that its decision to shut off power was necessary to protect public safety. 

Second, SDG&E should rely on other measures, to the extent available, as 

an alternative to shutting off power. These measures include reliance on 

 

26 SDG&E’s Tariff Rule 14 (A) states: “The utility will exercise reasonable diligence and 

care to furnish and deliver a continuous and sufficient supply of electric energy to 

the customer, and to avoid any shortage or interruption of delivery of same.” 

27 Tariff Rule 14, Section A. 

28 D.09-09-030 at 57. 

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sensitive relay settings to shut off power in milliseconds if there is an electrical 

failure caused by power lines falling to the ground and disabling reclosers to 

keep power off until SDG&E can inspect its facilities to determine if it is safe to 

re-energize its power lines. As CPSD notes, these measures might have 

prevented the catastrophic Witch Fire in October 2007 without shutting off 

power prematurely. 

Third, the data provided by SDG&E shows that most facilities do not fail 

in strong winds, and most failures do not result in a fire. SDG&E must 

reasonably believe there is an imminent and significant risk that strong 

Santa Ana winds will topple its power lines onto tinder dry vegetation during 

periods of extreme fire hazard. The factors that SDG&E should consider, and 

which we may evaluate after the fact, include the following: 

• The wind speed at the location(s) where power is shut off and 

the wind direction to the extent this affects the wind load on 

the facilities. 

• The type of facilities at the location(s) where power is shut off 

(e.g., Grade A or Grade B, wood or steel, etc.); the wind load 

design basis for the facilities; the age and condition of the 

facilities; and the percent utilization (i.e., the actual safety 

factor). 

• The calculated risk of wind-caused structural failures. 

• The vegetation conditions where power is shut off 

(e.g., vegetation fuel load and fuel-level moisture). 

• Whether the National Weather Service has declared a 

Red Flag Warning due to extremely low humidity or low 

humidity plus strong winds. 

The above factors are illustrative, not inclusive. 

Fourth, we may consider SDG&E’s efforts to mitigate the adverse impacts 

on the customers and communities in areas where SDG&E shuts off power. Such 

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mitigation must include appropriate and feasible steps to warn and protect its 

customers whenever SDG&E shuts off power in Santa Ana wind conditions 

pursuant to its statutory authority. Appropriate mitigation might include, for 

example, alternate sources of electric power for critical public services such as 

schools and water utilities. 

Finally, we may consider other factors, as appropriate, to assess whether 

SDG&E’s decision to shut off power was reasonable and should be exempt from 

liability under Tariff Rule 14. 

We decline to adopt CPSD and DRA’s position that SDG&E should be 

prohibited from shutting off power at wind speeds below 91 mph (for Grade A 

facilities). As noted previously, there is a risk that SDG&E’s existing facilities 

may fail at wind speeds below 91 mph. It would be extremely dangerous to 

prohibit SDG&E from shutting off power when SDG&E reasonably believes 

there is an imminent danger of energized power lines falling onto tinder dry 

vegetation in Santa Ana wind conditions and there are no other safety measurers 

available (e.g., automatic re-closers) to prevent a fire. 

So that we may monitor shutoff events, SDG&E shall notify the Director of 

CPSD no later than 12 hours after SDG&E shuts off power because, in part, 

SDG&E believes that strong winds could cause a structural failure of SDG&E’s 

overhead power-line facilities. After the shut off has ended, SDG&E shall 

provide a report to the Director of CPSD that includes (i) an explanation of 

SDG&E’s decision to shut off power; (ii) all factors considered by SDG&E in its 

decision to shut off power, including wind speed, temperature, humidity, and 

vegetation moisture in the vicinity of the de-energized circuits; (iii) the time, 

place, and duration of the shutoff event; (iv) the number of affected customers, 

broken down by residential, medical baseline, commercial/industrial, and other; 

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(v) any wind-related damage to SDG&E’s overhead power-line facilities in the 

areas where power is shut off; (vi) a description of the notice to customers and 

any other mitigation provided by SDG&E; and (vii) any other matters that 

SDG&E believes are relevant to the Commission’s assessment of the 

reasonableness of SDG&E’s decision to shut off power. 

SDG&E shall submit the report no later than 10 business days after the 

shutoff event ends. The report shall be verified by an SDG&E officer pursuant to 

Rule 1.11 of the Commission’s Rules of Practice and Procedure. 

CPSD may investigate each reported incident and prepare an order 

instituting investigation, if appropriate. The need for, and the outcome of, any 

investigation proceeding will be decided on a case by case basis taking into 

account all facts and circumstances. 

We recognize that in D.09-09-030, the Commission authorized SDG&E to 

file an application for approval of a comprehensive fire-prevention program, 

including a provision to shut off power during periods of strong winds. 

However, as discussed previously in today’s decision and in D.09-09-030, 

SDG&E has statutory authority to shut off power when necessary to protect 

public safety, subject to after-the-fact review by the Commission. The 

application contemplated by D.09-09-030 does not apply to the exercise of 

SDG&E’s statutory authority to shut off power. 

4.4.3. Design Requirements 

Today’s decision does not determine if SDG&E has correctly interpreted 

and applied GO 95 wind-load design requirements. We will address the 

appropriate design standards on a prospective basis in Phase 3 of 

Rulemaking 08-11-005. There, we will convene workshops where parties will 

develop proposals for revising GO 95 to include (1) a new High Fire-Threat 

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District where there is an elevated risk of power-line fires occurring and 

spreading rapidly; and (2) design standards for overhead power-line facilities in 

the new High Fire-Threat District. These workshops will also assess if the new 

design standards developed in Phase 3 should apply to existing facilities and, if 

so, to develop a plan, timeline, and cost estimate for upgrading existing 

facilities.29

5. Comments on the Proposed Decision 

The proposed decision of the assigned ALJ for this proceeding was mailed 

to the parties in accordance with Pub. Util. Code § 311, and comments were 

allowed in accordance with Rule 14.3 of the Commission’s Rules of Practice and 

Procedure. Comments were filed on April 9, 2012, by the Communications 

Providers, DisabRA, MGRA, SCE, and SDG&E. Reply comments were filed on 

April 16, 2012, by CPSD and SDG&E. These comments have been reflected, as 

appropriate, in the final decision adopted by the Commission. 

6. Assignment of the Proceeding 

Timothy Alan Simon is the assigned Commissioner and Timothy Kenney 

is the assigned ALJ for this proceeding. 

Findings of Fact 

1. Santa Ana winds are strong, dry winds that occur from time to time in 

SDG&E’s service territory. Santa Ana winds can damage overhead power-line 

facilities. Fires ignited by wind-damaged power lines can spread rapidly in 

Santa Ana wind conditions and cause enormous destruction. 

 

29 D.12-01-032 at 121 – 123 and Ordering Paragraph 8. 

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2. SDG&E has used a design basis for wind loads of 56 mph for most of its 

overhead power-line facilities. There is a risk that such facilities will experience 

structural failures when wind gusts exceed 56 mph. The risk of failure increases 

exponentially as wind speed increases. 

3. De-energizing overhead power lines eliminates the risk that power lines 

will ignite fires during Santa Ana winds, but it also imposes significant costs, 

burdens, and risks on the customers and communities where power is shut off. 

Conclusions of Law 

1. SDG&E has authority under Pub. Util. Code § 399.2(a) and § 451 to shut off 

power in emergency situations when necessary to protect public safety, 

including the situation where strong Santa Ana winds exceed the design basis for 

SDG&E’s overhead power-line facilities and threaten to topple energized power 

lines onto tinder dry brush. 

2. SDG&E should provide notice and mitigation to its customers, to the 

extent feasible and appropriate, whenever SDG&E shuts off power pursuant to 

its statutory authority. 

3. DisabRA’s petition to modify D.09-09-030 should be granted. 

4. Any decision by SDG&E to shut off power under its statutory authority, 

including the adequacy of any notice given and any mitigation measures 

implemented by SDG&E, may be reviewed by the Commission pursuant to its 

broad jurisdiction over matters regarding the safety of public utility operations 

and facilities. The Commission may decide at that time whether SDG&E’s 

decision to shut off power was reasonable and qualifies for an exemption from 

liability under SDG&E’s Electric Tariff Rule 14. 

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5. SDG&E should notify the Director of CPSD within 12 hours whenever 

SDG&E shuts off power because, in part, SDG&E believes that strong winds 

could cause a structural failure of SDG&E’s overhead power-line facilities. After 

the shut-off event has ended, SDG&E should submit a report to the Director of 

CPSD that includes the information specified in the body of today’s decision. 

6. Because this decision affects public safety, this decision should be effective 

immediately. 

ORDER 

IT IS ORDERED that: 

1. Disability Rights Advocates’ petition to modify Decision 09-09-030 is 

granted. San Diego Gas & Electric Company (SDG&E) shall take appropriate 

and feasible steps to provide notice and mitigation to its customers whenever 

SDG&E shuts off power pursuant to its statutory authority. 

2. San Diego Gas & Electric Company (SDG&E) shall notify the Director of 

the Commission’s Consumer Protection and Safety Division (CPSD) no later than 

12 hours after SDG&E shuts off power because, in part, SDG&E believes that 

strong winds could cause structural failures of SDG&E’s overhead power-line 

facilities. After the shut-off event has ended, SDG&E shall submit a report to the 

Director of CPSD that includes (i) an explanation of SDG&E’s decision to shut off 

power; (ii) all factors considered by SDG&E in its decision to shut off power, 

including wind speed, temperature, humidity, and vegetation moisture in the 

vicinity of the de-energized circuits; (iii) the time, place, and duration of the 

power shutoff event; (iv) the number of affected customers, broken down by 

residential, medical baseline, commercial/industrial, and other; (v) any 

wind-related damage to SDG&E’s overhead power-line facilities in the areas 

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where power is shut off; (vi) a description of the customer notice and any other 

mitigation provided by SDG&E; and (vii) any other matters that SDG&E believes 

are relevant to the Commission’s assessment of the reasonableness of SDG&E’s 

decision to shut off power. SDG&E shall submit the report no later than 

10 business days after the shutoff event ends. The report shall be verified by an 

SDG&E officer in accordance with Rule 1.11 of the Commission’s Rules of 

Practice and Procedure. 

3. Application 08-12-021 is closed. 

This Order is effective today. 

Dated April 19, 2012, at San Francisco, California. 

MICHAEL R. PEEVEY 

 President 

TIMOTHY ALAN SIMON 

MICHEL PETER FLORIO 

CATHERINE J.K. SANDOVAL 

MARK J. FERRON 

 Commissioners 

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