Exhibit 12.3

Commonwealth Edison Company

Ratio of Earnings to Fixed Charges

	Years Ended December 31,
	2008		2009			2010			2011			2012
Pre-tax income from continuing operations		329		602			693			666			618
Plus: Loss from equity investees		9		—			—			—			—
Less: Capitalized interest		3		(3	)		(2	)		(4	)		(3	)
Pre-tax income from continuing operations after adjustment for income or loss from equity investees and capitalized interest		341		599			691			662			615
Fixed Charges:
Interest expensed and capitalized, amortization of debt discount and premium on all indebtedness		323		301			368			330			297
Interest component of rental expense (a)		8		7			6			6			6
Total fixed charges		331		308			374			336			303
Pre-tax income from continuing operations after adjustment for income or loss from equity investees, capitalized interest plus fixed charges		672		907			1,065			998			918
Ratio of earnings to fixed charges		2.0		2.9			2.8			3.0			3.0

(a) Represents one-third of rental expense relating to operating leases, which is a reasonable approximation of the interest factor.