Exhibit 12(a)

UNS Energy Corporation

Computation of Ratio of Earnings to Fixed Charges

	Nine Months Ended		Twelve Months Ended		Twelve Months Ended
	September 30,		September 30,		December 31,		December 31,		December 31,		December 31,		December 31,
	2012		2012		2011		2010		2009		2008		2007
	- Thousands of Dollars -
Fixed Charges:
Interest on Long-Term Debt	$	53,811	$	72,788	$	73,217	$	65,020	$	58,134	$	70,227	$	73,095
Other Interest (1)		1,683		2,290		2,535		1,651		3,468		1,837		5,480
Interest on Capital Lease Obligations		27,419		38,725		44,874		52,540		53,682		57,272		64,499
Estimated Interest Portion of Rental Expense		617		848		926		240		345		188		258
Total Fixed Charges	$	83,530	$	114,651	$	121,552	$	119,451	$	115,629	$	129,524	$	143,332
Net Income	$	83,414	$	91,601	$	109,975	$	112,984	$	105,901	$	16,955	$	60,712
Add:
Losses from Equity Investees		—		—		—		5,570		1,834		713		340
Income Tax Expense		51,430		55,466		66,951		76,921		63,232		18,747		40,274
Total Fixed Charges		83,530		114,651		121,552		119,451		115,629		129,524		143,332
Total Earnings before Taxes and Fixed Charges	$	218,374	$	261,718	$	298,478	$	314,926	$	286,596	$	165,939	$	244,658
Ratio of Earnings to Fixed Charges		2.614		2.283		2.456		2.636		2.479		1.281		1.707

⁽¹⁾ Excludes recognition of Allowance for Borrowed Funds Used During Construction.