Install 33kV Underground Cable - Stage 1 & 2

Install underground cable 3
Install underground cable 4

Key Facts

  • Project: Install 33kV Underground Cable ‐ Stage 1 & 2
  • Client: WEL Networks Limited
  • Location: Te Kowhai North West of Hamilton, New Zealand
  • Contract Value: NZ$766,000.00

DESCRIPTION

With the growth in Hamilton Northern suburbs WEL Networks brokered a solution with the National Grid owner Transpower New Zealand Limited, for a new point of supply at Te Kowhai, North and West of Hamilton City. WEL were concerned that in the event of faults at Transpower Hamilton or Western Road substation, the supply to the growing Hamilton City could be jeopardised. Electrix has been successful with two projects associated with the Te Kowhai 33kV cable works and has won this work, evaluated by WEL on their weighted average attribute evaluation method, which analyses not only price but also methodology, resources and relevant experience.

SCOPE

Electrix was initially awarded package ‘A’ from the Te Kowhai substation in Bedford Road to Horotiu Road. The work entailed open trenching for four separate circuit options being; two circuits of 3550 metres in length from Bedford Road to Horotiu Road; and one circuit from Te Kowhai substation to Bedford Road of 700m in length, these circuits used single core 630mm2 ALXLPE.

The Fourth circuit from Te Kowhai substation to Horotiu Road shared the trench with one of the 630mm2 above for part of its length and was 3670m long using single core 800mm2 ALXLPE. Also included as part of this contract was a 12 core fibre optic cable installed between the electrical cable circuits. Jointing of the single mode gel filled optical fibre was inclusive of the installation.

Most of the trenching was confined to the roadside, however to avoid disruption to the Te Kowhai village, part of the route ran, cross country, North of the residential area, this route traversed a very swampy gully and the work was confined to the summer months to limit the amount of water to be contended with. Just the same it proved to be quite a challenge for our trenching sub contractor “Utility installations” and they had to apply to Environment Waikato to build a dam upstream of the trench to hold the water. The dam includes a 300mm diameter pipe, complete with filter to direct the water over the trench. WEL Networks Ltd supplied all the materials and arranged for delivery of the cable on an as required basis. This limited the storage space required and ensured greater security with the aluminum cable. Once all the cable was laid and mid span joints completed Electrix was awarded a further contract to complete all testing and cable terminations.

The cables have an outside diameter of 80mm and a mass of 15kgs per metre. These were cut above the bridge and threaded through the abutment onto cable racking suspended from the under side of the bridge. The cable was winched across the racking and re‐joined.

The day of the cable pull, the number of personnel on site swelled to over 50 to basically man handle the over 2 tonne of cable in large snake like curves to its new location.

VALUE TO CLIENT

The client had the entire 33kV system commissioned on time with an excellent quality of workmanship. The project was accident free and the client very satisfied.

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