Detached Garage or ADU? Why We Often Discuss 400 Amp Service During Preconstruction

considering a detached structure? one upgrade. huge impact.

One of the things we spend a lot of time discussing during preconstruction isn’t necessarily what a home needs today—it’s what it might need ten, twenty, or even thirty years from now.

Whether we’re building a custom home, a detached garage, a garage apartment, or an accessory dwelling unit (ADU), we try to help homeowners think beyond the immediate project and consider how their property might evolve with their needs.

Recently, we collaborated with our trade partner, Eric Meyler of Meyler Electric, to install a 400-amp electrical service on a project. Whenever homeowners hear “400 amps,” the first question is usually:

“do i really need that much power?”

The answer is: maybe. That is why having these discussions upfront makes all the difference.

it’s not about today

Most homes function perfectly well with a 200-amp service.

The challenge is that the way we use electricity is changing.

Electric vehicles are becoming more common.

Heat pumps continue gaining popularity.

Induction cooking is replacing gas in many homes.

Detached garages, workshops, accessory dwelling units (ADUs), backyard cottages, pool houses, and home offices are all increasing electrical demand.

When you start stacking those items together, available electrical capacity can disappear surprisingly fast.

The detached structure conversation

Many homeowners throughout North Carolina know they want additional space eventually, but they aren’t ready to build it today.

Sometimes it’s a future workshop.

Sometimes it’s a detached garage.

Sometimes it’s an accessory dwelling unit for aging parents, guests, rental income, or adult children returning home.

That’s where planning can make a significant difference. Installing larger electrical infrastructure during initial construction is often substantially easier and less expensive than upgrading after everything is complete.

Once landscaping is installed, driveways are poured, and structures are finished, making changes becomes much more complicated.

Sometimes the most valuable upgrade isn’t the one you use immediately.

It’s the one that gives you options later.

flexibility has value

One of the reasons we advocate for these conversations is because flexibility matters.

As a custom home builder, we’ve learned that homeowners rarely regret creating options for the future.

Maybe you will never buy an electric vehicle.

Maybe you never build the detached workshop you’ve been talking about.

Maybe your needs never change.

That’s completely okay.

But if they do, you’ll be glad you considered the possibility before the walls were closed up and the trenches were backfilled.

Good planning isn’t about predicting the future perfectly.

It’s about leaving room for it.

there isn’t a one-size-fits-all answer

. It’s important to note that we don’t recommend 400 amp service for every project.

We’ve built homes with both 200 amp and 400 amp services.

Every family, budget, property, and long-term goal is different.

Our job isn’t to make decisions for our clients.

Our job is to help them understand their options so they can make informed decisions for themselves.

Sometimes the right answer is 200 amps. Sometimes it’s 400.

The key is having the conversation before construction is complete.

final thoughts

The best building decisions are often the ones nobody notices after move-in.

They aren’t flashy.

They don’t show up in listing photos.

Years later, when life changes, and your home can adapt without major headaches, those decisions start looking pretty smart.

If you’re planning a detached garage, accessory dwelling unit (ADU), workshop, garage apartment, or custom home in North Carolina, it’s worth discussing your electrical service early in the process.

Your future self might thank you for it.

As always, consult your local builder and electrician.

— the cruz built team