FIFTY-FIFTH SUPPLEMENTAL INDENTURE FROM SAN DIEGO GAS & ELECTRIC COMPANY TO U.S. BANK NATIONAL ASSOCIATION

Exhibit 4.1

RECORDING REQUESTED BY RECORDED MAIL TO:

U.S. BANK NATIONAL ASSOCIATION

633 W. FIFTH STREET, 24 ^th FLOOR

LOS ANGELES, CA 90071

ATTN: CORPORATE TRUST SERVICES

Index as a UCC Filing and an Indenture

This is a Security Agreement and a Mortgage of Chattels

as well as a Mortgage of Real Estate and Other Property

FIFTY-FIFTH SUPPLEMENTAL INDENTURE

FROM

SAN DIEGO GAS & ELECTRIC COMPANY

TO

U.S. BANK NATIONAL ASSOCIATION

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Dated as of May 14, 2009

TABLE OF CONTENTS*

THIS FIFTY-FIFTH SUPPLEMENTAL INDENTURE IS A SECURITY

AGREEMENT AND A MORTGAGE OF CHATTELS AS WELL AS

A MORTGAGE OF REAL ESTATE AND OTHER PROPERTY

THIS FIFTY-FIFTH SUPPLEMENTAL INDENTURE, dated as of the fourteenth day of May 2009, by and between SAN DIEGO GAS & ELECTRIC COMPANY, a corporation duly organized and existing under and by virtue of the laws of the State of California, having its principal office in that State in the City of San Diego (the “ Company ”), and U.S. BANK NATIONAL ASSOCIATION, a banking association duly organized under an act known as the “National Bank Act,” of the United States of America, having a corporate trust office in the City of Los Angeles, State of California, as Trustee (the “ Trustee ”).

WHEREAS, the Company executed and delivered a Mortgage and Deed of Trust (the “ Original Indenture ”), dated July 1, 1940, to The Bank of California, National Association, as predecessor trustee to Bankers Trust Company of California, National Association, as predecessor trustee to First Trust of California, National Association, (subsequently renamed U.S. Bank Trust National Association) as predecessor trustee to the Trustee, to secure payment of the principal of and the interest on all bonds of the Company at any time outstanding thereunder according to their tenor and effect, and to provide the terms and provisions with respect to its First Mortgage Bonds, 3  ³ / 8 % Series due July 1, 1970, issued in the aggregate principal amount of $16,000,000 and heretofore retired; and

WHEREAS, the Company executed and delivered to the then current trustee, a First Supplemental Indenture dated as of December 1, 1946, a Second Supplemental Indenture dated as of March 1, 1948, a Third Supplemental Indenture dated as of April 1, 1952, a Fourth Supplemental Indenture dated as of April 1, 1954, a Fifth Supplemental Indenture dated as of October 1, 1955, a Sixth Supplemental Indenture dated as of October 1, 1957, a Seventh Supplemental Indenture dated as of October 1, 1960, an Eighth Supplemental Indenture dated as of March 1, 1967, a Tenth Supplemental Indenture dated as of December 1, 1968, an Eleventh Supplemental Indenture dated as of February 1, 1970, a Twelfth Supplemental Indenture dated as of September 1, 1971, a Thirteenth Supplemental Indenture dated as of January 15, 1974, a Fourteenth Supplemental Indenture dated as of December 15, 1974, a Fifteenth Supplemental Indenture dated as of May 1, 1975, a Seventeenth Supplemental Indenture dated as of July 15, 1976, an Eighteenth Supplemental Indenture dated as of March 15, 1977, a Nineteenth Supplemental Indenture dated as of May 1, 1978, a Twentieth Supplemental Indenture dated as of March 15, 1980, a Twenty-First Supplemental Indenture dated as of August 1, 1980, a Twenty-Second Supplemental Indenture dated as of July 15, 1981, a Twenty-Third Supplemental Indenture dated as of January 15, 1982, a Twenty-Fourth Supplemental Indenture dated as of August 16, 1982, a Twenty-Fifth Supplemental Indenture dated as of August 16, 1982, a Twenty-Sixth Supplemental Indenture dated as of August 16, 1982, a Twenty-Seventh Supplemental Indenture dated as of June 2, 1983, a Twenty-Eighth Supplemental Indenture dated as of July 15, 1983, a Twenty-Ninth Supplemental Indenture dated as of September 1, 1983, a Thirty-First, Supplemental Indenture dated as of May 1, 1984, a Thirty-Second Supplemental Indenture dated as of December 1, 1984, a Thirty-Third Supplemental Indenture dated as of September 1, 1985, a Thirty-Fourth Supplemental Indenture dated as of December 1, 1985, a Third-Fifth Supplemental Indenture dated as of July 1, 1986, a Thirty-Sixth Supplemental Indenture dated as of December 1, 1986, a Thirty-Seventh Supplemental Indenture dated as of September 1, 1987, a Thirty-Eighth Supplemental Indenture dated as of April 15, 1990, a Thirty-Ninth Supplemental Indenture dated as of December 1, 1991, a Fortieth Supplemental Indenture dated as of April 1, 1992, a Forty-First Supplemental Indenture dated as of June 15, 1992, a Forty-Second Supplemental Indenture dated as of September 1, 1992, a Forty-Third Supplemental Indenture dated as of December 1, 1992, a Forty-Fourth Supplemental Indenture dated as of April 1, 1993, a Forty-Fifth Supplemental Indenture dated as of June 1, 1993, a Forty-Sixth Supplemental Indenture dated as of July 1, 1993, a Forty-Seventh Supplemental Indenture dated as of June 1, 1995, a Forty-Eighth Supplemental Indenture dated as of June 1, 1995, a Forty-Ninth Supplemental Indenture dated as of June 1, 2004, a Fiftieth Supplemental Indenture dated as of May 19, 2005, a Fifty-First Supplemental Indenture dated as of November 17, 2005, a Fifty-Second Supplemental Indenture dated as of June 8, 2006, a Fifty-Third Supplemental Indenture dated as of September 1, 2006, and a Fifty-Fourth Supplemental Indenture dated as of September 20, 2007, whereby, among other things, the Company set forth certain of the particulars of the Bonds of series designated “First Mortgage Bonds, 2 3/4% Series due December 1, 1981” issued in the aggregate principal amount of $2,800,000, “First Mortgage Bonds, Series C due 1978” issued in the aggregate principal amount of $10,000,000, “First Mortgage Bonds, Series D due 1982” issued in the aggregate principal amount of $512,000,000, “First Mortgage Bonds, Series

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E due 1984” issued in the aggregate principal amount of $17,000,000, “First Mortgage Bonds, Series F due 1985” issued in the aggregate principal amount of $18,000,000, “First Mortgage Bonds, Series G due 1987” issued is the aggregate principal amount of $12,000,000, “First Mortgage Bonds, Series H due 1990” issued in the aggregate principal amount of $30,000,000, “First Mortgage Bonds, Series I due 1997” issued in the aggregate principal amount of $25,000,000, “First Mortgage Bonds, Series J due 1998” issued in the aggregate principal amount of $35,000,000, “First Mortgage Bonds, Series K due 2000” issued in the aggregate principal amount of $40,000,000, “First Mortgage Boards, Series L due 2001” issued in the aggregate principal amount of $45,000,000, “First Mortgage Bonds, Series M due 2004” issued in the aggregate principal amount of $75,000,000, “First Mortgage Bonds, Series N due 1979” issued in the aggregate principal amount of $50,000,000, “First Mortgage Bonds, Series O due 1982” issued in the aggregate principal amount of $40,000,000, “First Mortgage Bonds, Series P due 2006” issued in the aggregate principal amount of $45,000,000, “First Mortgage Bonds, Series Q due 2007” issued in the aggregate principal amount of $50,000,000, “First Mortgage Bonds, Series R due 2008” issued in the aggregate principal amount of $50,000,000, “First Mortgage Bonds, Series S due 2010” issued in the aggregate principal amount of $50,000,000, “First Mortgage Bonds, Series T due 2010” issued in the aggregate principal amount of $75,000,000, “First Mortgage Bonds, Series U-1 due 1984, and U-2 due 1994” issued in the aggregate principal amount of $6,567,000 for Series U-1 and $13,268,000 for Series U-2, “First Mortgage Bonds, Series V due 2011” issued in the aggregate amount of $50,000,000, “First Mortgage Bonds, Series W due 1988” issued in the aggregate principal amount of $40,000,000, “First Mortgage Bonds, Series X due 1987” issued in the aggregate principal amount of $20,000,000, “First Mortgage Bonds, Series Y due 1987” issued in the aggregate principal amount of $15,000,000, “First Mortgage Bonds, Series Z, due 2013” issued in the aggregate principal amount of $65,000,000, “First Mortgage Bonds, Series AA, due 2018” issued in the aggregate principal amount of $150,000,000, “First Mortgage Bonds, Series BB, due 2018” issued in the aggregate principal amount of $150,000,000, “First Mortgage Bonds, Series CC, due 2008” issued in the aggregate principal amount of $53,000,000, “First Mortgage Bonds Series DD, due 2008” issued in the aggregate principal amount of $27,000,000, “First Mortgage Bonds, Series EE, due 2015” issued in the aggregate principal amount of $100,000,000, “First Mortgage Bonds, Series FF, due 2007” issued in the aggregate principal amount of $35,000,000, “First Mortgage Bonds, Series GG, due 2021” issued in the aggregate principal amount of $44,250,000, “First Mortgage Bonds, Series HH, due 2021” issued in the aggregate principal amount of $381,350,000, “First Mortgage Bonds, Series II due 2023” issued in the aggregate principal amount of $25,000,000, “First Mortgage Bonds, Series JJ, due 2015” issued in aggregate principal amount of $100,000,000, “First Mortgage Bonds, Series KK, due 2015” issued in the aggregate principal amount of $14,400,000, “First Mortgage Bonds, Series LL, due 2022” issued in the aggregate principal amount of $60,000,000, “First Mortgage Bonds, Series MM due 2002” issued in the aggregate principal amount of $80,000,000, “First Mortgage Bonds, Series NN” issued in the aggregate principal amount of $118,615,000, “First Mortgage Bonds, Series OO” issued in the aggregate principal amount of $250,000,000, “First Mortgage Bonds, Series PP, due 2018” issued in the aggregate principal amount of $70,795,000, “First Mortgage Bonds, Series QQ, due 2018” issued in the aggregate principal amount of $14,915,000, “First Mortgage Bonds, Series RR, due 2021” issued in the aggregate principal amount of $60,000,000, “First Mortgage Bonds, Series SS, due 2018” issued in the aggregate principal amount of $92,945,000, “First Mortgage Bonds, Series TT due 2020” issued in the aggregate principal amount of $57,650,000, “First Mortgage Bonds, Series UU due 2020” issued in the aggregate principal amount of $16,700,000, “First Mortgage Bonds, Series VV due 2034” issued in the aggregate principal amount of $43,615,000, “First Mortgage Bonds, Series WW due 2034” issued in the aggregate principal amount of $40,000,000, “First Mortgage Bonds, Series XX due 2034” issued in the aggregate principal amount of $35,000,000, “First Mortgage Bonds, Series YY due 2034” issued in the aggregate principal amount of $24,000,000, “First Mortgage Bonds, Series ZZ due 2034” issued in the aggregate principal amount of $33,650,000, “First Mortgage Bonds, Series AAA due 2039” issued in the aggregate principal amount of $75,000,000, “First Mortgage Bonds, Series BBB due 2035” issued in the aggregate principal amount of $250,000,000, “First Mortgage Bonds, Series CCC due 2015” issued in the aggregate principal amount of $250,000,000, “First Mortgage Bonds, Series DDD due 2026” issued in the aggregate principal amount of $250,000,000, “First Mortgage Bonds, Series EEE due 2018” issued in the aggregate principal amount of $161,240,000, and “First Mortgage Bonds, Series FFF due 2037” issued in the aggregate principal amount of $250,000,000, respectively, all of which First Mortgage Bonds have heretofore been retired or redeemed, except the Series KK due 2015, the Series OO, the Series RR due 2021, the Series VV due 2034, the Series WW due 2034, the Series XX due 2034, the Series YY due 2034, the Series ZZ due 2034, the Series AAA due 2039, the Series BBB due 2035, the Series CCC due 2015, the Series DDD due 2026, the Series EEE due 2018 and the Series FFF due 2037, which are presently issued and outstanding; and

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WHEREAS, certain of the provisions of the Original Indenture have been amended by the aforesaid Second and Tenth Supplemental Indentures, a Ninth Supplemental Indenture dated as of August 1, 1968, a Sixteenth Supplemental Indenture dated August 28, 1975, and a Thirtieth Supplemental Indenture dated September 23, 1983; and

WHEREAS, the Original Indenture and each of said Supplemental Indentures have been recorded in the Official Records of the Recorders of the Counties of San Diego, Orange, Riverside, and Imperial in the State of California and the Counties, Yuma and Maricopa in the State of Arizona, as follows:

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