*

Plan includes $1.43 bln investment in electricity for

first rate

year

*

Includes $290 mln in bill discounts, pipe retirement

*

Final decision expected in coming months

(Adds details in paragraph 3-4, 6)

April 28 (Reuters) - Britain's National Grid said

on Monday it had filed a three-year rate plan proposal with the

New York Public Service Commission for its upstate New York

electric and natural gas distribution business.

Niagara Mohawk Power Corporation ( NMPWP ) , which serves 1.7

million electric and 600,000 gas customers, represents around

15% of National Grid's regulated asset base.

If the proposed plan is approved, residential electricity

customers using an average of 625 kilowatt-hours (kWh) per month

would see monthly bills rise by $14.32 in the first year, $6.44

in the second, and $4.34 in the third.

Residential natural gas customers using an average of 78 therms

per month would see monthly bills rise by $7.66 in the first

year, $8.08 in the second, and $9.18 in the third, the company

said.

The plan, which will run from May 2025 to March 2028,

includes a return on equity of 9.5%, and capital investment of

$1.43 billion in electricity and $351 million in gas for NIMO in

the first rate year, National Grid said.

It also includes more than $290 million in bill discounts, and

retirement of about 112 miles (180 km) of leak-prone natural gas

pipe in the next three years, the company added.

A final decision from the commission is expected in the next

few months.