Enlargement of the station was undertaken during the spring of 1899, with new equipment including a fourth 125 hp boiler; a Buckeye 400 hp horizontal cross-compound engine direct-connected to a General Electric 250 Kw. multipolar direct current generator with an output of 550 volts, and a General Electric 125 Kw. 2,300 volt, 60 cycle alternator.
This new apparatus increased the direct current capacity of the station to 500 kilowatts, but because of the distance of the plant from Amesbury, some 12 miles, the EH&A made arrangements to purchase additional electric current, when needed, from the Amesbury Electric Light Company. There was some talk of constructing a direct current feeder line from the power station across country to Hampton Falls but so far as can be determined, this never was provided.
The new alternator was installed to permit the EH&A to improve its commercial power facilities and it was driven by the Buckeye tandem-compound engine formerly used to run the Brush arc light generator, which was discarded. Part of the alternator's output was applied to a new tank converter, supplying current for the street lights in Exeter, while the remainder fed the new primary lighting circuit extending from the power station to the Hampton Beach Casino.
A 154-ft. artesian well, with 140 feet in solid rock, was drilled to furnish a new supply of feed water for the power station boilers and a 10,000 gal. tank was mounted on an 80-foot steel tower. The original 80-foot steel stack outside the boiler house was replaced by a 150-foot brick chimney. Like the carhouse, the power station was protected by automatic sprinklers.
(With the construction of the new Hampton carhouse in 1902, a main was laid from the foot of the power station tank across Exeter Road to supply water for the sprinkler system in the brick barn).
During mid-1901, shortly after the Rockingham County Light and Power Company commenced building its new plant at Portsmouth, a wood frame addition .was constructed on the south side of the EH&A's power station and a General Electric 500 Kw., 13,200 volt, three-phase 25 cycle alternator, direct-driven by a Rice & Sargent 700 hp cross-compound condensing engine, was installed. Three Dillon boilers were provided to furnish steam for the new unit, which was to energize substations at Amesbury and Plaistow pending completion of the Port City facility.
Because of delays in the erection of high tension transmission lines from Hampton to Amesbury and Plaistow, the new engine and generator were not placed in service until March 12, 1902, the Amesbury substation being commissioned the same day. About a month later, work began on the construction of a permanent substation addition to the Hampton plant, and during May, current from Hampton was transmitted to Plaistow for the newly-opened Haverhill-Plaistow-Amesbury line.
(Reportedly, the temporary addition and the new generating equipment and boilers were owned by the Haverhill, Plaistow & Newton Street Railway instead of the EH&A).
The Portsmouth plant was placed in commission Aug. 8, 1902 and thereafter supplied all power for the Eastern, Western and Northern Divisions of the New Hampshire Traction Company's railway system. The new Hampton substation served as a distribution center, 13,20 volt 25-cycle alternating current from Portsmouth being fed to high tension transmission lines extending to the substations at Amesbury and Plaistow on the Eastern Division and at Salem and Pelham on ,the Western Division. In addition, a portable substation, EH&A No. 400, was in service at Hampton Beach (later at Seabrook Beach) during the summer months.
After the opening of the Portsmouth plant, the Hampton power station was used for auxiliary purposes only and after the provision of additional generating capacity at Portsmouth in 1903, most of the equipment at Hampton was removed and sold. All that remained in the old power station at the time of the EH&A receivership were two Ames 125 hp tubular boilers, the Buckeye 175 hp tandem-compound engine and the General Electric 2,300 volt alternator. Railway equipment in the substation consisted of two General Electric 300 Kw. rotary converters, six General Electric 125 Kw. 13,200/370 volt air-cooled transformers, reactive coils, blowers and alternating and direct current panels.
According to the Electrical World and Engineer of October 11, 1902, the EH&A's street lighting service in Exeter employed 77 General Electric series alternating enclosed arc lamps and 45 series incandescent lamps rated at 32 candle power each. Including the street lights at Hampton Beach and lights in the hotels, casino, cottages and other buildings there, the railway's lighting department carried an additional load of about 1,600 incandescent lamps of 16 cp. each. This was about all the alternator at Hampton could handle and during 1903, with the extension of lighting lines to Seabrook Beach and Rye Beach, the Rockingham County Light & Power began furnishing commercial power from Portsmouth. This 60 cycle current was transmitted at 6,600 volts to Hampton, where it was transformed to 2,200 volts for the distribution system.
According to the receiver's inventory, this distribution system consisted of a primary circuit from Hampton to the Exeter opera house, with a branch extending from the opera house to a box factory by way of Main, Lincoln, Garfield, School and Front Streets. A second primary branch extended through Front Street to School Street while a third ran from Front Street through Pine and Court Streets.
Another primary circuit ran from the power station to Seabrook Beach via Hampton Beach, while a third circuit ran from Hampton to Straw's Point, Rye. The second circuit had an additional wire for street lighting service in Hampton, and the third circuit had a primary branch extending east and west at Rye Beach. The primary circuit to Straw's Point and the branches at Rye Beach were sold to the Rockingham County Light & Power Company effective May 1, 1907 as the EH&A had no authority to conduct a commercial power business in the town of Rye. The circuit to Seabrook Beach was retained, however.