The 12 month project involved upgrading and strengthening overhead power lines, electricity substations and underground cables ready for winter.
ENW spent £20 million upgrading 10,000 electricity poles, 653 pylons and 191km of overhead power lines.
It also spent £3.7 million cutting back trees posing a risk to the cables.
ENW said the investment will benefit more than five million customers across its network.
ENW chief executive Steve Johnson said: “Thankfully for most people power cuts are very rare, but they can have a big impact – particularly if you’re not prepared.
“Severe weather can damage the network and cause power cuts which is why we have been working hard over the past year investing and preparing for this winter.”
The network is also supporting the Government’s ‘Get Ready For Winter’ campaign by asking customers to think about what they would do in a power cut.