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COMMITMENTS AND CONTINGENCIES - Schedule of Number of Sites and Reserves (Details) - site | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Loss Contingencies [Line Items] |  |
Number of Sites | 65 | 59
CL&P |  |
Loss Contingencies [Line Items] |  |
Number of Sites | 16 | 13
NSTAR Electric |  |
Loss Contingencies [Line Items] |  |
Number of Sites | 12 | 10
PSNH |  |
Loss Contingencies [Line Items] |  |
Number of Sites | 8 | 8

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