How to Change a 100 Amp Breaker Box to a 200 Amp Breaker Box

Obtain a building or remodeling permit from your local building inspector. This permit allows for significant changes to be made to a structure and, in almost all cases, is required by law.

Call the local electric company and have the electrical service terminated for that location for the scheduled installation day. This may be done temporarily, for example, for one to two days, and is different than a standard service termination.

Equip all electrical safety equipment. This includes electrical safety gloves, goggles and work boots.

Test the main connection into the breaker box with the multimeter to verify that there is no current and the power was turned off by the electric company.

Draw a diagram detailing the connections of every wire and to which breaker they are connected. All connections, including neutral wires, busbar connections and the circuit "hot wire" must be accounted for. This diagram acts as a guide when installing the new panel.

Loosen all mounting bolts holding wires in place. Tuck these wires away for a cleaner work environment.

Turn all breakers into the "off" or "open" position.

Remove all breaker switches from the breaker box. You will reuse these breakers in the new 200-amp breaker box.

Loosen the "lug" bolts at the main breaker. This main breaker is not removable and contains the highest amperage rating within the panel.

Remove the panel mounting bolts. These bolts connect the panel to the structure or home.

Remove the 100-amp breaker box from the wall by pulling it away from the wall in a perpendicular direction. This may require some force if the panel has been installed for many years.

Install the new panel and replace the mounting bolts. Often, the new 200-amp breaker box requires new mounting bolts because there is no standard size in relation to the breaker box capacity.

Remove the face plates blocking access to the new breaker slots. Pry off these plates using a screwdriver.

Insert the breakers removed from the 100-amp breaker box. Although you don't have to place them exactly as they were oriented previously, place them relatively close to their old installation location so the wires can reach them in their new positions.

Remount all wires according to your diagram. These wires are mounted by wrapping their exposed metal surfaces around the mounting screws and tightening the screws just enough to hold them securely in place.

Mount the service wires to the new lug bolts in the service panel. Tighten these wires firmly in place.

Turn the breakers into the "on" or "closed" position. Turn on the main breaker first, followed by the smaller circuit breakers.

Have the installation inspected by a licensed electrical professional. Though this step is optional, it is highly advised for safety purposes. An electrical professional will guarantee you made no mistakes that could result in injury or property damage when you turn on the electricity. In some cases, a building inspector may be required to examine the work before deeming the property safe for electrical power reactivation.

Inform the electric company to reestablish electrical service to the structure.