Niagara Mohawk Power Corporation d/b/a National Grid PURPOSE: THE FILING OF REVISED RATES TO P.S.C. NO. 220 ELECTRICITY, P.S.C. NO. 214 STREETLIGHTING, and P.S.C. NO. 219 GAS TARIFFS TO COMPLY WITH THE COMMISSION'S ORDER DATED AUGUST 14, 2025 IN P.S.C. CASES 24-E-0322 AND 24-G-0323. TEXT: Notice is hereby given that Niagara Mohawk Power Corporation d/b/a National Grid has filed with the Public Service Commission to comply with the Commission's order dated August 14, 2025, to become effective, on a temporary basis, September 1, 2025. The tables listed below show a comparison between the Company's current rates (prior to September 1, 2025) to rates effective September 1, 2025, by service classification. Other changes effective September 1, 2025: 1) Service Re-establishment and Disconnection Charges have been updated per Rule 9 of P.S.C. No. 220 and per Rule 20 of P.S.C. No. 219. Electric Rates Service Classification No. 1 – Residential Current Rates Rates Effective September 1, 2025 Basic Service Charge $17.33 $19.00 Distribution Delivery Charge per kWh $0.07576 $0.08889 Service Classification No. 1C – Time of Use Residential Current Rates Rates Effective September 1, 2025 Basic Service Charge $30.62 $30.62 Distribution Delivery Charge per kWh $0.04068 $0.03649 Service Classification No. 2 – Non-Demand Small General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $21.02 $25.00 Distribution Delivery per kWh $0.08685 $0.09902 Service Classification No. 2 – Demand Small General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $53.57 $65.00 Distribution Delivery per kW $14.85 $16.99 Service Classification No. 3 – Secondary Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $675.00 $775.00 Distribution Delivery per kW $12.35 $14.28 Service Classification No. 3 – Primary Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $700.00 $850.00 Distribution Delivery per kW $11.18 $12.88 Service Classification No. 3 – Sub Transmission/Transmission Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $1,150.00 $1,430.00 Distribution Delivery per kW $3.46 $4.07 Service Classification No. 3 A– Secondary/Primary Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $3,000.00 $3,525.00 Distribution Delivery per kW $12.39 $14.07 Service Classification No. 3 A – Sub Transmission Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $3,700.00 $4,350.00 Distribution Delivery per kW $4.32 $4.97 Service Classification No. 3 A– Transmission Large General Service Current Rates Rates Effective September 1, 2025 Basic Service Charge $7,500.00 $8,800.00 Distribution Delivery per kW $4.28 $4.36 For more information, visit http://www.nationalgridus.com or the PSC's website: https://dps.ny.gov/ Street Lighting Rates Service Classification No. 1 – Private Lighting Current Rates Rates Effective September 1, 2025 Distribution Delivery Charge per kWh $0.09886 $0.11826 Service Classification No. 2/5 – Street Lighting Current Rates Rates Effective September 1, 2025 Distribution Delivery Charge per kWh $0.09886 $0.11826 Service Classification No. 3 – Street Lighting Current Rates Rates Effective September 1, 2025 Distribution Delivery Charge per kWh $0.06787 $0.08094 Service Classification No. 4 – Traffic Controls Current Rates Rates Effective September 1, 2025 Distribution Delivery Charge per kWh $0.01234 $0.01496 For more information, visit http://www.nationalgridus.com or the PSC's website: https://dps.ny.gov/ Gas Rates Service Classification No. 1 – Residential Non-Heat and Heat Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $21.40 $22.50 Next 47 therms, per therm $0.71722 $0.85236 Over 50 therms, per therm $0.15553 $0.19652 Service Classification No. 2 – Small General Service Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $26.00 $28.60 Next 277 therms, per therm $0.42349 $0.47764 Next 4,720 therms, per therm $0.25520 $0.28783 Over 5,000 therms, per therm $0.09107 $0.15078 Service Classification No. 5 – Firm Gas Sales and Transportation Monthly usage Current Rates Rates Effective September 1, 2025 First 100 therms or less $718.00 $800.00 Over 100 therms, per therm $0.09562 $0.11339 Service Classification No. 6 – Large Volume Interruptible Transportation Monthly usage Current Rates Rates Effective September 1, 2025 First 100 therms or less $581.27 $668.50 Over 100 therms, per therm $0.04732 $0.05035 Service Classification No. 7 – Small Volume Firm Gas Sales and Transportation Monthly usage Current Rates Rates Effective September 1, 2025 First 2,100 therms or less $350.00 $375.00 Next 400 therms $0.45479 $0.51616 Next 1,700 therms, per therm $0.33923 $0.36680 Over 4,200 therms, per therm $0.13790 $0.17025 Service Classification No. 8 – Gas Sales and Transportation Service with Standby Sales Monthly usage Current Rates Rates Effective September 1, 2025 First 100 therms or less $1,650.00 $1,785.00 Next 99,900 therms, per therm $0.09712 $0.11599 Next 400,000 therms, per therm $0.09141 $0.10917 Over 500,000 therms, per therm $0.07887 $0.09418 Service Classification No. 12 – Distributed Generation Less than 250,000 therms per year Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $200.00 $230.00 Over 3 therms, per therm (Apr to Oct) $0.05165 $0.07040 Over 3 therms, per therm (Nov to Mar) $0.06735 $0.09143 Service Classification No. 12 – Distributed Generation Greater than 250,000 but less than 1,000,000 therms per year Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $500.00 $575.00 Over 3 therms, per therm (Apr to Oct) $0.05012 $0.06188 Over 3 therms, per therm (Nov to Mar) $0.06001 $0.07369 Service Classification No. 12 – Distributed Generation Greater than 1,000,000 but less than 2,500,000 therms per year Monthly usage Current Rates Rates Effective September 1, 2025 First 100 therms or less $1,550.00 $1,782.50 Next 499,900 therms, per therm (Apr to Oct) $0.04562 $0.05655 Next 499,900 therms, per therm (Nov to Mar) $0.05595 $0.06908 Over 500,000 therms, per therm (Apr to Oct) $0.03912 $0.04848 Over 500,000 therms, per therm (Nov to Mar) $0.04797 $0.05923 Service Classification No. 12 – Distributed Generation Greater than 2,500,000 therms per year Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $1,550.00 $1,782.50 Over 3 therms, per therm (Apr to Oct) $0.00892 $0.01123 Over 3 therms, per therm (Nov to Mar) $0.01123 $0.01406 Demand charge per therm of MPDQ $0.91222 $1.14269 Service Classification No. 13 – Residential Distributed Generation Monthly usage Current Rates Rates Effective September 1, 2025 First 3 therms or less $28.00 $32.20 Over 3 therms, per therm $0.11458 $0.15677 For more information, visit http://www.nationalgridus.com or the PSC's website: https://dps.ny.gov/ Niagara Mohawk Power Corporation d/b/a National Grid September 4, 11, 18, 25 2025 LNYS0355751