QO Circuit Breaker Load Centers, PK18GTAL, from Square D are Underwriters Laboratories (UL) Listed and CSA rated panelboards. They are designed to meet residential, commercial, and industrial requirements to protect electrical systems, equipment, and people. All metering stacks are shipped from the factory with meter sockets and vertical bus bars pre-installed, and require a minimum of on site labour time to install the circuit breakers and main bus links. Provision to lock and seal the circuit breaker handles in the off position has been made for the convenience of utilities and electrical inspectors. This main tap box with 1200A rated main bus and main 1 phase service can provide (3) AWG 4-750 MCM or (4) AWG 4-600 MCM in aluminium or copper lug size. The unit comes in sizes of height 19 in, 23 in width and 9.55 in of depth. All meter stacks are designed for CSA Type A cold metering in which the individual sub-service breakers are connected on the line side of the meter sockets thereby protecting the meter and all electrical equipment installed subsequent to it.