National Grid (LSE: NG.) shares are quietly becoming one of the stock market’s go-to defensive plays. Volatility is back. Investors are looking for stability.

As a regulated utility, its earnings are largely shielded from economic cycles. Instead, they are driven by long-term infrastructure investment and regulatory frameworks. That gives the business strong visibility. In today’s uncertain macro environment, that matters more than ever.

But the investment case may be shifting. This is no longer just a defensive income story. Electricity networks now sit at the centre of two major structural trends: the rise of artificial intelligence and the rapid electrification of industry and transport.

That changes the narrative. The question is no longer just about stability. It’s whether the market fully recognises the company’s role in powering the next wave of demand growth.

Electrification

What is changing is not the regulatory model, but the demand placed on it. Electricity networks are no longer supporting a stable, mature system — they are becoming the constraint in a rapidly electrifying economy.

AI infrastructure, data centres, and the shift towards electric transport and heating are all driving a step-change in power demand. Crucially, that demand does not spread evenly across the system. It concentrates around grid capacity, turning networks into a critical bottleneck.

That has important implications. When capacity becomes scarce, investment follows — and for regulated operators, that feeds directly into a growing asset base and higher allowed returns over time. In effect, demand growth translates into earnings visibility rather than volatility.

Seen through that lens, National Grid looks less like a passive income stock and more like core infrastructure for a structurally expanding electricity system.

Accelerating demand

That demand story is not theoretical — it’s already feeding through into investment plans.

The company is currently working to connect up to 19GW of additional electricity demand in the UK by the early 2030s. Strikingly, roughly half of that is expected to come from data centres alone — a clear signal of how quickly AI is reshaping electricity consumption.

To support that, investment is ramping up at pace. More than £5bn was deployed in the first half alone, with full-year spending expected to exceed £11bn. Over the longer term, a £60bn programme is set to expand the regulated asset base, driving roughly 10% annual growth.

That matters because, in a regulated model, higher investment feeds directly into future earnings. What looks like a stable utility on the surface is, in reality, gearing up for a sustained period of demand-led expansion.

What’s the verdict

Of course, there are risks. National Grid’s growth depends on heavy investment, which means higher debt. If interest rates stay elevated, borrowing costs could rise and put pressure on returns and the share price.

At the same time, as a regulated business, allowed returns are not entirely within management’s control, creating some uncertainty over how quickly higher costs can be passed through.

That said, in my view, the scale of demand now building across electricity networks is easy to underestimate. As investment translates into a larger asset base and more predictable earnings, I see this as a business with both defensive qualities and long-term growth potential — which is why I view the stock as one to consider.