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The bulk of the construction work has now been completed, and the year's activities have been confined to the following :— Transmission-lines.—The 66 kV. line was completed from Otira to Arahura and from Kaiata to Dobson. The latter included two and three-quarters miles of 33 kV. line converted to 66 kV. Twenty-eight miles of line were constructed between Dobson and Blackwater, and eight miles between Dobson and Arnold. The latter consisted in the most part of a 33 kV. line converted to 66 kV. Of the 11 kV. distribution lines eight miles were constructed from Arahura to the Arahura and Kanieri dredges. A short length of single-circuit line was constructed to connect the Grey Power Board's system to the site of the Ngahere Substation. Approximately two miles of double-circuit 11 kV. line was constructed from Otira Substation to the tunnel portal. Telephone-lines.—During the year a telephone-line was constructed over Arthur's Pass to Otira to form an alternative route to the line through the tunnel and to serve as a patrol-line. Another line from Jacksons to Arahura approximately thirty miles is under construction. Substations.—Dobson: This 66/11 kV. substation was completed and put into service in October. Nine panels were added to the 11 kV. switchgear and the Power Board feeders gradually changed over from Kaiata Substation, the latter now being out of service. Arahura : First livened up and went into service in November last. Since then four 66 kY. 0.C.8.'s have been erected, together with the necessary control gear and relays, and placed in service. The 5,000 kVA. synchronous condenser was erected complete and put into service in May, 1939. This completes the major work at this substation, but a good deal of work has yet to be done on the grounds. Blackwater : Construction work at this substation was completed during the year, and it was put into service in October, supplying power to the Grey Electric-power Board and the Grey River dredge. Ngahere : This substation was partially built, sufficient to permit the 66 kV. lines in and out to be connected to their proper switches. The major part of the construction work has yet to be done and this is now in hand. (h) Wigram Aerodrome. Extensive low-tension underground reticulation was carried out and is continuing to be extended A 450 kVA. transformer bank was installed for temporary supply, and work is proceeding on the necessary adjustments and testing of the switchgear. (2) Operation and Maintenance. (a) Power-stations. General. —During the year the Lake Coleridge and Waitaki stations operated in parallel satisfactorily with Waipori in parallel as required. In December Monowai was paralleled and, after satisfactory voltage adjustments, has since operated as part of the system. In March the West Coast system was paralleled with Coleridge, the Diesels at Dobson being first used, and later Arnold River Station. The two systems have operated quite satisfactorily, the Diesels now being shut down, but are ready to be brought in as required to ease the system peaks. Lake Coleridge Power-station.—A very heavy flood in the Harper River in April, 1938, caused considerable damage to the eastern end of the main diversion groyne at the Harper intake, and destroyed two of the protective groynes a short distance below the main groyne. Repair work, due to adverse conditions, has been slow, but it is now well in hand. The extremely dry conditions for the first three months of this year have made it necessary to turn the full river flow into the lake and, as well, to construct a bag dam at the gates. Now that construction has been completed at the Harper intake the maintenance staff has been reduced to three men. The Acheron diversion was in use for about five months during the year. The lake-level caused slight anxiety in May of this year, due to its fall to 1,666-525 ft. but, due to heavy rains, the level is rising again, that at the end of May being 1,666-9 ft. An explosion occurred in a section of the 6-6 kY. indoor switchgear in June. Extensive damage was caused to the control cables, excitation leads and 6-6 kY. cables, while rendering all 7,500 kW. machines inoperative. The work of repair was undertaken by the Test Department, while later the walls of the switch gallery and control-room were cleaned and distempered. No. 1 unit was shut down in August for removal and renewing of the rubber packing-rings and welding of the scored parts of the piston and sleeve and internal body of the main valve. At the same time the turbine was opened up for general inspection. No. 2 unit, which was shut down in February, was recommissioned in June of last year, after steel protecting-rings had been fitted to the runner. In December one of the guide-vanes of this unit was broken, causing severe damage to the runner blades. This was repaired by welding. Considerable trouble was experienced due to foreign matter becoming lodged in the turbine guide-vanes of Nos. 4, 5, 6, and 8 machines, several gate-operating links being broken. New bronze rings were fitted to the main gate of No. 8 unit. This unit was shut down on another occasion to reduce side clearance of gates. Waitaki Power-station. —The average monthly river-flow varied from 26,300 cusecs to 5,010 cusecs. The automatic lake-level recorders at Lakes Ohau, Pukaki, and Tekapo were inspected periodically. Routine maintenance-work has otherwise been carried out, both the main and the auxiliary generating-sets operating quite satisfactorily throughout.

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