Do I Need a Separate Electric Meter for My ADU?

By Buz Artiano, BuildX | November 2025

Every week we talk to people who have this exact question: should they spend $2,000 to $4,000 on a separate electric meter, or save that money and put it towards better appliances? We have built a lot of ADUs here in Massachusetts and we have seen families regret both decisions actually. The ones who don't opt for a separate meter are usually calling us about three years later because they can't rent out their ADU without a ton of expensive electrical work. But the ones who paid for the separate meter a lot of times wonder if it was worth it or if they should have put that money towards better appliances.

At BuildX, our experience has taught us that it's not really about the meter at all, it's about understanding your property's future. We build ADUs all over Massachusetts, and the meter question comes down to three things: your town's requirements, whether you want to rent out the unit, and how long you plan to own the property. You need to get all of this right or you could spend $10,000 later to fix a $3,000 decision you made today.

What Are Your Three Meter Options?

Massachusetts ADU owners have three metering configurations to choose from, each with different costs and functions.

A shared meter means your ADU just pulls power from the main house and there is no separate bill. This adds zero installation cost, but you also can't legally rent the unit to anybody who isn't family, and you have no way to track the ADUs individual power usage.

A sub-meter is a smaller device that tracks ADU electricity usage while the power still flows through your main service. It only costs about $500 to $800 to install, and you can read the meter yourself to figure out how to fairly split the cost of the bill. But sub-meters don't create a separate utility account, which means they don't satisfy rental requirements.

A separate meter establishes an independent utility account for your ADU with its own billing from the power company. Installation runs $2,000 to $4,000 depending on your property's infrastructure. You also have to pay an extra monthly service fee of $15 to $25 for the second account. The advantage is complete independence: your renter receives their own bill and is responsible for paying the electric company themselves, and your property has more value because of the flexibility.

Why Do Town Requirements Vary So Much?

Massachusetts is under statewide ADU laws, but local authorities can still interpret the electrical requirements differently. Some towns require separate meters on all ADUs regardless of their usage. Other towns let you share meters for family use, but still make you have separate service if you're going to rent it out. And there are a few towns that leave the decision completely up to you.

We've seen inspectors in one town approve shared metering while the next town over requires separate service for the exact same plans. The language in Massachusetts code is ambiguous, and local building departments interpret it their own way. Before committing to any path, contact your local building department directly. Ask specifically whether shared meters are permitted for what you intend to use the ADU for.

How Much Power Does an ADU Actually Need?

Your metering decision is relevant to your ADU's power requirements. All-electric ADUs with heat pumps, electric stoves, and electric dryers typically require a 200-amp service and pull around 120 amps with everything running at once. The current code says you have to have a 60-amp outlet for future electric vehicle charging, which makes the amperage requirement a lot higher than most people expect.

If you choose gas appliances for heating, cooking, and laundry, your electrical needs go down quite a bit. A gas appliance ADU might only need 100 to 150 amps at the most, with normal draw being around 60 to 80 amps. Doing it this way sometimes allows you to connect to the existing 200-amp house service as long as it is managed correctly.

We always recommend a separate 200-amp service for ADUs whenever possible. The cost difference between 150-amp and 200-amp service is next to nothing and with the 200 amps you'll never run out of power as appliances upgrade or EV charging becomes necessary.

What Hidden Costs Should You Budget For?

The meter itself represents only part of your electrical costs. There are other expenses that affect your total budget.

Panel upgrades cost $1,500 to $3,000 if your existing panel can't support additional capacity. Trenching is a big part of the cost as well, $50 to $100 per foot depending on soil conditions and distance to the main connection point. Utility companies charge connection fees between $500 and $1,500 to establish new service. The meter socket and disconnect hardware add $400 to $600. Finally, permits and inspections typically run $200 to $500 depending on your town.

Small spaces such as ADUs can create other concerns. Building code requires three feet of clearance in front of electrical panels. In smaller units, where space is very limited, we can install weather-rated panels on the outside of the house to make sure you get the most out of your interior space.

When Does a Separate Meter Make Sense?

Separate meters is the better choice for most situations, even though it costs quite a bit more.

If you plan to rent your ADU at any point in the future, make sure you install the separate meter during construction. Going back and doing it later costs so much more than installing it during the build. If you want exact records of ADU energy costs for budgeting or tax purposes, you have to have a separate meter so you have utility-verified documentation that you can't get with a sub meter. If you are ever going to sell the property, separate metering increases resale value by giving potential buyers more options and flexibility.

If your ADU will have its own solar setup, you need separate metering to establish net metering credits and track solar generation from the ADUs panels.

When Can You Skip the Separate Meter?

We build plenty of ADUs with shared meters when the situation calls for it.

If your ADU will be a permanent home for family members with no intentions to ever rent it out, and your town allows it, shared metering is a fine solution. If you need to save some money and you understand that you cannot rent the ADU out in the future, the money you save could be a big help if the budget is tight. And keep in mind that if your town does not allow ADU rentals, it's not really worth it to pay for separate metering.

The important thing to think about is permanence. Building codes evolve, family circumstances change, and properties get sold. The $3,000 you save today could cost you $10,000 to go back and fix in five or ten years.

How Does BuildX Handle Meter Installation?

We manage the entire electrical process for every single ADU we build. We communicate directly with the utility company, pull all necessary permits, and schedule the inspections. When you're ready to set up your account, we give you all the phone numbers and walk you through the easy process.

During construction, we use your existing electrical service temporarily. This usually adds about $500 to your electric bill over the 100 day period. Once we install the ADU meter, the new account gets all set up and your bill goes right back to normal for the main house.

For properties where separate service makes sense, we almost always install a 200-amp underground service from the utility pole to the ADU. This gives you completely separate service and bills to keep all your options open for the future of your ADU.

What Meter Configuration Fits Your Situation?

You should make your decision based on four things. One, are you planning to rent the ADU at any point in the next decade? Two, does your town allow shared metering? Three, do you want to track ADU power usage separately from the main house? And last, do you plan on selling the property in the future?

If you plan on renting out your ADU, then the separate meter is a must. If family housing is the permanent arrangement, then shared metering with a sub-meter is a great option. If you're unsure whether you will sell the property in the future, we suggest the separate meter because it gives you insurance in case your circumstances change.

Ready to Plan Your ADU's Electrical System?

You need to decide about the meter at the beginning of the process, before trenching starts and walls are closed up. Changing your mind mid-construction costs a lot of extra time and money that could have been avoided.

BuildX offers complimentary site evaluations where we assess your property's electrical infrastructure, discuss your intended use, and recommend the metering configuration that fits your situation. Our team handles utility coordination, permitting, and installation so you can focus on the parts of your ADU project that matter most to you.