PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Schedule of Utility Property, Plant and Equipment

The following tables summarize property, plant and equipment by asset category:

Eversource	As of December 31,
(Millions of Dollars)	2021		2020
Distribution - Electric	$	17,679.1	$	16,703.2
Distribution - Natural Gas	6,694.8		6,111.2
Transmission - Electric	12,882.4		11,954.0
Distribution - Water	1,900.9		1,743.1
Solar	200.9		201.5
Utility	39,358.1		36,713.0
Other (1)	1,469.5		1,269.0
Property, Plant and Equipment, Gross	40,827.6		37,982.0
Less:  Accumulated Depreciation
Utility	(8,885.2)		(8,476.3)
Other	(580.1)		(477.6)
Total Accumulated Depreciation	(9,465.3)		(8,953.9)
Property, Plant and Equipment, Net	31,362.3		29,028.1
Construction Work in Progress	2,015.4		1,854.4
Total Property, Plant and Equipment, Net	$	33,377.7	$	30,882.5

	As of December 31,
	2021						2020
(Millions of Dollars)	CL&P		NSTAR Electric		PSNH		CL&P		NSTAR Electric		PSNH
Distribution - Electric	$	7,117.6	$	8,105.5	$	2,496.2	$	6,820.7	$	7,544.4	$	2,378.4
Transmission - Electric	5,859.0		5,090.5		1,934.6		5,512.0		4,701.3		1,742.4
Solar	—		200.9		—		—		201.5		—
Property, Plant and Equipment, Gross	12,976.6		13,396.9		4,430.8		12,332.7		12,447.2		4,120.8
Less:  Accumulated Depreciation	(2,572.1)		(3,227.3)		(908.4)		(2,475.4)		(3,074.1)		(848.9)
Property, Plant and Equipment, Net	10,404.5		10,169.6		3,522.4		9,857.3		9,373.1		3,271.9
Construction Work in Progress	399.0		707.0		134.1		377.3		750.0		102.4
Total Property, Plant and Equipment, Net	$	10,803.5	$	10,876.6	$	3,656.5	$	10,234.6	$	10,123.1	$	3,374.3

(1)These assets are primarily comprised of computer software, hardware and equipment at Eversource Service and buildings at The Rocky River Realty Company.

The depreciation rates for the various classes of utility property, plant and equipment aggregate to composite rates as follows:

(Percent)	2021		2020		2019
Eversource	3.1	%	3.0	%	3.0	%
CL&P	2.8	%	2.8	%	2.8	%
NSTAR Electric	2.8	%	2.8	%	2.8	%
PSNH	3.1	%	2.8	%	2.8	%

The following table summarizes average remaining useful lives of depreciable assets:

	As of December 31, 2021
(Years)	Eversource	CL&P	NSTAR Electric	PSNH
Distribution - Electric	33.4	35.3	33.1	29.7
Distribution - Natural Gas	39.5	—	—	—
Transmission - Electric	40.2	36.5	45.1	40.8
Distribution - Water	38.5	—	—	—
Solar	24.2	—	24.2	—
Other (1)	11.2	—	—	—

(1)The estimated useful life of computer software, hardware and equipment primarily ranges from 5 to 15 years and of buildings is 40 years.