1. Panels and Subpanels

2. Main Service Panel aka Load Center The Load Center is the heart and soul of a home’s electrical system. It: – Serves as a distribution center for all branch circuits – Houses all overcurrent protection devices that protect individual branch circuits – Houses a master switch which cuts off power to the entire house

3. Types of Load Centers There are many types of load centers, but most fall into a couple categories: – Indoor – Outdoor – With Main Breaker – Without Main Breaker The most common application is indoor and it is a best practice to use the “With Main Breaker” type.

4. Sizes of Load Centers Load Centers come in all shapes and sizes. Some homeowners and contractors try to save a few bucks and go with the smallest one that will work. Honestly though, it is not worth the extra effort and down stream hassles. For the primary load center, I suggest a full size indoor load center equipped with a main breaker.

5. Subpanels Some installations call for the installation of a subpanel. A subpanel is typically used for situations that would benefit from another panel to protect a set of branch circuits. For example: – Detached garages – Workshops – Barns and Outbuildings

6. Elements of the Load Center Four Main Elements: – Main Breaker – Hot Bus – Neutral Bus – Grounding Bus

7. The Main Breaker The main breaker is located at the top of the load center. All electricity coming into the home flows (or should flow) through the main breaker. It’s primary purpose is to provide overcurrent protection to all wiring in the home. It’s secondary purpose is to serve as a main disconnect in the event of an emergency such as a fire. Some load centers are not equipped with a main breaker. When replacing the load center, make sure to always install a main breaker equipped unit.

8. The Hot Bus The main breaker transfers power to the hot bus. The hot bus consists of two copper or aluminum strips that run down the middle of the load center and are located immediately below the main breaker. The hot bus distributes power to the circuit breakers. Each leg of the bus is the same voltage when compared to neutral but acts as an independent power source.

9. The Hot Bus Con’t. Bridging across both bus bars, the voltage doubles. The circuit breaker for each branch circuit attaches to the hot bus. In turn, the black wire is attached to the circuit breaker. In a 240v branch circuit, the black and red wires are attached to the circuit breaker.

10. Neutral Bus The neutral bus provides a common return point for current, thus completing the circuit. The neutral bus consists of two long aluminum strips with many screws and are located along the sides of the load center. The screws serve as attachment points for each branch circuit. The white wire is attached to the neutral bus

11. Ground Bus The ground bus is located in the “gutter” of the load center. It is similar in shape and design to the neutral bus, two long strips with many screws. This bus serves as the attachment point for the ground wire in each branch circuit. The neutral bus is connected to the ground bus. The ground bus is connected to a 6 AWG wire which is then connected to the home’s ground

12. The Load Center This is the standard layout of a load center prior to installation. You will need to be able to identify all items listed from memory.