How the Lights Stay On

Chapter 5: The Last Hundred Feet

A few years after I lived in the old Hoboken apartment with the blinking bulbs, I moved.

The new place was only a few blocks away. Same neighborhood. Same utility company. Same grid feeding the same streets. The only thing that changed was the building. The new one was newer, larger, built in this century rather than the last one. The wiring inside the walls had been put in by people who knew that twenty-first-century apartments would have central air conditioning, microwaves, dishwashers, gaming computers, and an EV charger or two somewhere in the future.

I turned on the AC the first hot night. The bulbs did not blink.

I stood there for a moment in my new living room and looked at the lamp. I turned the AC off. I turned it back on. The motor hummed to life. The bulbs stayed bright. Steady. Quiet. Boring.

That was when I understood something that had been hiding in plain sight for years.

The grid above my head had been the same grid the whole time.

The thing that had changed was the building.

The Blink from Chapter 1 was not really a grid problem. It was a building problem.

This is one of the most important distinctions in the entire book, and almost nobody outside the electrical trades makes it cleanly. So let’s make it cleanly here.

When you flip a switch in your house, the electricity reaching your bulb has been on a journey through two different systems, run by different companies, regulated by different rules, built to different standards.

The first system is the grid — the synchronized machine, the transmission lines, the substations, the high-voltage wires. This is what we have been talking about for four chapters. It is the system run by your utility company and watched over by control rooms in places like Audubon, Pennsylvania.

The second system is the building you live in. The wires running through the walls. The service panel — sometimes called the breaker box — in the basement or the hallway closet. The outlets. The light switches.

These two systems meet at a place called the service drop — the wires that come down from the utility pole into your house, or up out of the ground in newer developments. Everything before the service drop is the grid’s responsibility. Everything after it is the building’s.

When the grid fails, you get a blackout. Everyone on your block goes dark. The utility sends a crew.

When the building fails, you get a blink. A flicker. A breaker that keeps tripping when you run the microwave and the toaster at once. A burning smell from an outlet that you should absolutely not ignore. The utility does not help with this. You call an electrician.

Most people never have to think about which kind of problem they are having. The reason most Americans never have to think about it is that, for the second system to work reliably, somebody had to build the house correctly. And for old buildings, “correctly” was defined a long time ago.

There are about a hundred feet of wire between the transformer on the pole outside your house and the outlet next to your bed. Maybe a little more. Maybe a little less. Inside that hundred feet lives most of the small electricity problems most people will ever experience.

There are three usual suspects.

Undersized service. When your house was built, the electric company brought in a wire sized for the demand expected at the time. In the 1950s, that might have been 60 amps. In the 1970s, 100 amps. New houses today usually get 200 amps. A 60-amp service was fine when “high demand” meant a refrigerator, a few lights, and an electric stove. It is not fine when you add central air conditioning, a clothes dryer, a microwave, a dishwasher, a hair dryer, three televisions, a gaming computer, and a car charger. The wires coming in are too thin. The breaker box is too small. Every time you ask for a lot of current at once, the system strains.

Old wiring inside the walls. The actual wires running between your outlets and your panel might be older than you are. In houses built before the 1960s, the insulation around the wires is sometimes a fabric-and-rubber compound that becomes brittle with age. Touching a brittle wire can crack the insulation. Cracked insulation can cause short circuits and fires. There is also an infamous period in the 1960s and 1970s when American builders used aluminum wiring instead of copper, because copper had gotten expensive. Aluminum wiring is not inherently dangerous, but it expands and contracts more than copper, and the connections at outlets and switches can loosen over decades. Loose connections produce heat. Heat produces fires. The U.S. Consumer Product Safety Commission still considers homes with the original 1960s-70s aluminum wiring to be a real fire risk.

A tired transformer outside. The gray canister on the pole — or the green box in the yard, in newer developments — was originally sized for the load of the buildings it serves. If those buildings were sized for 1965 demand, and the neighborhood has not been upgraded, the transformer is doing more work than it was designed for. It may run hot. It may sag in voltage when the neighborhood collectively turns on its air conditioners at 6 PM. The blink in your apartment may not actually be coming from inside your apartment at all. It may be coming from a transformer that has been on the pole since the Johnson administration.

The hot summer night in my old Hoboken apartment, the blinking bulb might have been any of these three. Probably some combination. The new building I moved to had been wired in this century by people who expected modern loads, was connected to a properly sized transformer, and had a panel large enough to absorb the inrush current of an air conditioner without flinching.

The grid was the same. The last hundred feet had changed.

Take a walk around an older American neighborhood. Look up.

You will see gray canisters mounted on the utility poles, every few houses or so. They are about the size of a small barrel. They hum slightly. They are usually painted a dull gray and have warning labels with lightning bolts on them. Sometimes the wires coming off them have insulation that is a little faded. Sometimes there is a leak of oily liquid on the side, which is the cooling oil that keeps the transformer from overheating. Sometimes they are covered in pigeon mess.

Almost nobody notices them.

These are the workhorses of the last hundred feet. Each one is a step-down transformer — the same kind of equipment we met in Chapter 3, only much smaller. The wires coming down from the top carry the distribution voltage — usually around 7,000 volts, sometimes 13,000 volts. The wires coming out the bottom carry the much lower 240 volts that goes into your house.

A pole-mounted transformer typically serves anywhere from one house to a dozen, depending on the neighborhood. They are designed to last twenty to thirty years. Many of them have been hanging on those poles for forty or fifty.

When a pole transformer fails outright, the houses it serves go dark and the utility comes to replace it within hours. But long before they fail, transformers can age in ways nobody notices. They can lose efficiency. They can become unable to handle peak loads as well as they could when they were younger. They can be the silent reason a whole block has blinky lights every August.

Most of the time, the utility does not replace a pole transformer until it fails. Why? Because there are tens of millions of them in the United States, and replacing them all proactively would cost a staggering amount of money — money that would come from the customers in higher bills. It is cheaper to wait for them to fail and then fix them.

This is a choice. It is not a bad choice. It is a trade-off — the same kind of trade-off we will see again and again in this book. Reliable, affordable, clean: pick two.

The last hundred feet of every American house is about to get a lot of attention.

Here is why. For most of the twentieth century, the electrical demands of an average house grew slowly. A house built in 1950 used much less electricity than one built today, but the growth was steady and predictable. Utilities and building codes kept up.

Now the demands are growing faster. Here are a few of the things many American houses are getting, or about to get:

Heat pumps. Replacing a gas furnace and a separate air conditioner with one electric system. Heat pumps are three to four times more efficient than gas, but they need a much larger electrical circuit than the air conditioner alone. A heat pump can pull 40 amps continuously on a cold day.

Electric vehicles. A modern home EV charger draws 32 to 48 amps. That is roughly the same as running an electric oven full blast for as many hours as you charge.

Induction stoves. Replacing gas stoves with induction is faster, cleaner, and safer — but induction stoves can pull 40 amps too.

Heat pump water heaters. Replacing a gas water heater with an electric one. Another 30 amps when it cycles on.

If a house adds a heat pump, an EV charger, an induction stove, and a heat pump water heater — which is the standard package for fully electrifying a home — the total demand can easily exceed the capacity of an older 100-amp service. The grid above the house is fine. But the wires coming into the house, and the panel inside the house, were not designed for this much electricity.

In many American cities, getting a service upgrade — replacing your old panel, and possibly running a thicker wire from the pole — can cost five thousand dollars or more and take six months to schedule. There is a national shortage of qualified electricians. And in many neighborhoods, even if every individual house could be upgraded, the local distribution transformer would have to be upgraded too, because the combined new demand of all the upgraded houses would exceed what the transformer was sized for.

This is the bottleneck for electrification in the United States. Not the grid. The last hundred feet.

Years ago, I lived in Shanghai for nine years and never experienced a blackout. The grid was steady. The lights never blinked. The country had built one of the most reliable urban grid systems in the world.

And the building I lived in was old — out of code, the wiring caught fire once, the handyman pulled charred copper out of the plaster while I watched.

The grid was fine. The building was a fire hazard. They were not the same system. They had not been built to the same standards. They had not aged at the same rate.

Most people, in most places, do not have these two layers in their heads as separate things. We say “the electricity is unreliable here” or “the electricity is great there” and we mean one thing. But the experience of electricity in a building is the product of two layers, multiplied together. A great grid feeding a bad building gives you Shanghai’s burned wires. A great grid feeding a good building gives you boring, reliable, unremarkable electricity — which is the goal, by the way, even though “boring” sounds like a backhanded compliment. An okay grid feeding an old American building gives you the Blink.

You can fix one layer without fixing the other. You can also leave both broken. Which combination you live in is mostly about where you happen to be — and, within a given place, mostly about the building.

The last hundred feet is where most personal decisions about electricity live.

Can you install solar on your roof? That depends on your panel, your wiring, your local transformer, and your utility’s rules. We will get to that.

Can you afford a home battery, and when does it make sense? That depends on your last hundred feet too.

Should you electrify everything in your house, and in what order? That depends on your existing panel, your wiring, and your utility’s incentive programs.

For now, look around your house. Find the breaker box. The panel will have a number on it — 60, 100, 150, or 200 amps. That number is how much electricity your last hundred feet was built to deliver, on the day someone installed it.

Look at the pole transformer on the street, if your neighborhood has them above ground. If it is dented, leaking, or covered in pigeons, it has been there a while.

Look at the outlets. If they are the old two-prong style rather than three-prong, your wiring is probably older than the moon landing.

None of this means your house is dangerous. Old houses in good repair can be perfectly safe. But it is good to know what you are working with.

The Blink, in retrospect, was a small message from the system. It was telling me that the last hundred feet had been built a long time ago, for a different kind of life, and was now being asked to do more than it had ever been designed to do.

It is, more and more, what the entire country’s last hundred feet is being asked to do.

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