Powerco is working through its five-year upgrade of Whanganui electricity network while dealing with some familiar challenges the winter winds can bring.

Poor weather caused power to be cut to some Westmere residents early Tuesday morning and around 40 other Whanganui properties were also without electricity.

Small pockets of Powerco customers across the lower North Island also experienced power cuts last weekend, which were caused by trees, debris or lines clashing in the strong winds.

Powerco is one year into a $1.27 billion, five-year investment programme.

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Network operations manager Phil Marsh said Powerco invested heavily in asset management and replacement to ensure the network remained safe and reliable.

"It has significantly increased the maintenance and replacement programmes across our entire network. Compared to historical levels, we are increasing maintenance by 26 per cent and asset replacement by 55 per cent."

Marsh said the cost of placing all existing overhead supply underground would be prohibitive, but some overhead lines had recently been put underground.

"One of these involved the removal of six supply lines that spanned the Whanganui River to a substation at Hatrick's Wharf. The second project involved the undergrounding of 3km of cable from the city's northern boundary, along SH3 to Virginia Rd to the Brassey Rd intersection."

Marsh said power supply for all new subdivisions was placed underground.