In the United States, there has been a growing trend of installing 400 Amp services in residential properties. With the increasing demand for power from modern appliances and electronics, higher amperage electric service has become a necessity. As a result, many homeowners, builders, and contractors are exploring the possibility of using two 200 Amp service panels instead.
It is not prohibited by the National Electrical Code (NEC) to install two 200 Amp panels if the residence has 400-amp service. However, the installation process differs depending on whether it includes a sub-panel or two independent disconnect panels, and there may be variations in local codes. To determine the specific local codes, it is recommended to contact the building inspection department in your area.
An experienced licensed electrician can provide you with the necessary information regarding installing two service panels in the event of a 400-amp service connection. When discussing this issue, it is important to comprehend the benefits and drawbacks of each type of installation.
In order to make an informed decision about your electrical service, it is important to consider the requirements and costs of each installation type. By examining both types of installations in-depth, you will have a solid foundation for making the best decision for your needs.
The Choice of Installations – Sub-Panel or Two Disconnect Panels
For residential properties with 400 Amp electrical service, the cost of installing a single 400 Amp service panel may be too high for some people. In such cases, contractors or builders often suggest installing two 200 Amp panels instead, which is a more cost-effective option.
There are other advantages to this option beyond cost savings. It is important to carefully consider both options and understand the differences between the two types of panel installations. This will help you have a meaningful conversation with your contractor or builder and make an informed decision.
Installing a Main Panel with a Sub-Panel
A sub-panel is typically installed when the main service panel does not have space for additional circuit breakers. It is commonly used in areas where the main service panel is hard to access, such as an upstairs apartment or a workshop with specialized power needs.
One significant difference between a sub-panel and a main service panel is the presence of the main disconnect switch. According to the National Electrical Code (NEC), all electrical installations require a main disconnect circuit breaker or switch.
This circuit breaker is usually located in the main service panel and is responsible for safely disconnecting power to all the branch circuits in the home.
Conversely, a sub-panel may be installed near the main service entrance panel or in a remote location like a detached garage or utility space. The power that supplies the sub-panel is taken from the main service panel, and the main disconnect circuit breaker provides protection for both the main panel and the sub-panel.
The Pros and Cons of Adding a Using a Sub-Panel
When installing a sub-panel, the size of the wire needed between the main panel and the sub-panel will depend on the specific installation. In some cases, it may be necessary to use the same size wire used to bring the electrical service from the meter to the main panel. This can increase the installation’s cost in terms of materials and labor.
When it comes to electrical installations, installing a sub-panel in locations that are difficult to access or in detached parts of a structure can be wise. For example, a sub-panel may be the best option if you have a workshop with special power requirements or a second-story rental apartment.
In addition to the convenience factor, there can be significant cost savings in copper wire alone when branch circuit runs are lengthy. It is important to note that installing a sub-panel should be done per local electrical codes and regulations.
Make sure to check with your local electrical codes before deciding to install a 200 Amp main panel and a 200 Amp sub-panel. Some areas may have extra requirements or prohibit this type of installation when a residential building has a 400 Amp service.
Installing Two 200 Amp Main Panels
In certain situations, opting for two 200 Amp main disconnect panels in your residential property might be more practical. For instance, installing a new main panel could be a viable choice if you’re building an addition to your home that requires new branch circuits. The same goes for constructing a workshop or garage.
The installation of each panel necessitates a service line that runs from the electrical meter base to the main panel. Depending on the local codes, a two-lug design may be required for the meter base to accommodate this type of installation.
A two-lug meter base has two neutral and two hot connection points on the service side, allowing for two separate service lines to be safely connected to the meter base and comply with certain electrical codes.
The Pros and Cons of Installing Two 200 Amp Main Panels
One way to achieve greater efficiency is to install a main disconnect on each panel located in different locations. This becomes even more practical if the second panel is situated in a separate structure such as a garage or a pool house.
It is quite common to have accessory structures on larger residential properties like pool cabanas, equipment sheds, or workshops. Similarly, rental units located on adjacent lots may also require separate power supplies.
While installing two main service panels with disconnects can enhance efficiency, it may entail slightly higher costs. Disconnect panels are relatively expensive compared to sub-panels, and running two separate service lines may also add to the expenses.
The number of main disconnects allowed in a residential structure may be limited by local electrical codes. Some codes may prohibit having multiple main disconnects in one structure, insisting on a single main disconnect that protects all electrical circuits in the house.
If your codes permit having multiple main disconnects, the building inspection department may still require a load demand calculation on the electrical system. This additional requirement can increase the cost of the installation.
Cost Considerations
When it comes to electrical installation for your home, cost is a major factor to consider. Several factors can impact the cost of an electrical installation.
The cost of copper, as well as parts like breakers and panel assemblies, continues to rise. Labor costs also play a significant role, and they can vary based on the region. Conducting a quick cost comparison can provide valuable insight when making a decision.
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| 400 Amp Service Panel | 200 Amp Main Disconnect with Sub-panel | Two 200 Amp Main Disconnects | |
| Service Panel Costs | $1,300 | $300 | $450 |
| Circuit Breaker Costs (16 branch circuits) | $96 | $96 | $96 |
| Branch Circuit Wiring (Average residential New Construction Runs) | $9.73 Per Foot | $9.73 Per Foot | $9.73 Per Foot |
| Service Line Costs (underground 400 Amp 240V Service Line) | $20 – $40 per linear foot | $20 – $40 per linear foot | $20 – $40 per linear foot |
What Does the National Electrical Code Say
The National Electrical Code is widely followed in the United States as a guideline for electrical codes. Even if your local area has not officially adopted the NEC, it is likely that many parts of your local code are similar to the NEC’s language.
Although there are no direct sections of the NEC code that specifically address service panel installations on 400 Amp service, the NEC does refer to 400 Amp service in terms of equipment requirements, installation practices, and the sizes of wiring required. The NEC indirectly addresses dual panel installations on 400 Amp service. (Reference NEC Section 310 for wire specifications and requirements)
What Other Considerations Must You Consider?
When determining the installation of your 400 Amp electrical service, several other aspects exist. If you are building a new structure, your plans will typically be reviewed by the building inspection department, who can offer advice on local regulations and requirements.
Licensed electricians are required for electrical installations in most areas, particularly service entry points. This is a wise choice. If you choose to install the electrical system yourself with a homeowner’s permit, expect the electrical inspectors to make regular visits to your job site.
Make Sure you Load Balance your Electrical System
The service panel for electrical systems consists of two sets of circuit breakers arranged on each side of the panel frame. These breakers receive power from one of the two legs of the 240-volt service that feeds the panel. The electrical load is balanced to ensure that your home’s electrical system draws power equally from each side of the service panel.
If one side of the panel draws more power than the other, it can cause an overload on some circuits. This overload can cause overheating and eventually lead to the failure of electrical components in your home’s system or appliances.
In some instances, local electrical codes may require a load calculation report for the electrical system installed in your home. Load balance calculations can be performed in several ways, usually by your electrician, who can provide an acceptable report.
Two Main Disconnects VS. A Sub-Panel
Due to your local electrical code, determining whether to install a sub-panel or a service panel may be simpler than you think. In some areas, installing a disconnect switch on the electrical supply lines that feed a sub-panel is mandatory.
Essentially, the combination of a disconnect switch and a sub-panel is quite similar to a service panel that has a disconnect switch instead of a sub-panel. The main difference is the added expense of purchasing a separate disconnect switch, the enclosure, and the labor required for installation.
Often, these expenses surpass the additional cost of a service panel with a main breaker already installed.
Our Recommendation
Ultimately, we have several suggestions to offer on this subject. It’s critical to carefully evaluate these suggestions as you determine which style of primary service panel is right for you.
- Consider your local codes and ensure that your plans comply with them to avoid potential issues.
- Seek guidance from your electrical contractor on which type of installation would best suit your needs.
- If you decide to perform the work yourself, frequently consult with the electrical inspector for guidance on your progress.
Given that situations, codes, and needs differ, it’s nearly impossible to recommend which type of installation is ideal for homes with 400 Amp service. Gather as much information as you can and make your decision accordingly.
Getting The Power Where You Need It
Ultimately, the objective is to ensure that your home has power wherever it is required. The primary objective is to provide this power in the most efficient and safe manner possible. With a well-installed electrical system, you can expect many years of hassle-free service.