Issue:
Installing Neutral Bonding Screw on QO & Homeline Load Centers
Product Line:
QO and Homeline load centers
Environment:
Box Bonding for High Amp, 150A and Above
Cause:
Application
Resolution:
All QO and Homeline load centers that are marked 'Suitable for Use as Service Equipment', will come from the factory with a Green Neutral Bonding Screw, to be installed when the load center is used in a Service Entrance Application.
When a load center is used as Service Equipment, the NEC requires that the neutral shall be bonded to the metal box. The Service Equipment is identified by the fact it includes the first disconnect of the incoming power from the Utility. For a single family house, many times the load center is the main panel, with the main breaker acting as the Service disconnect. In this panel, the green screw is used to bond (fasten) the neutral to the metal box. This is only done in the main panel.
NOTE: Any panels installed downstream of the main panel are called sub-panels, and the neutral in these panels must not be bonded to the box. Since many Load Centers can be used as either the main panel, or as a sub-panel, the green screw is included with the load center to be used in the appropriate installation.
The green screw is also commonly called the "Neutral Bonding Screw", or the "Bonding Screw".
Refer to the Wiring Diagram Label of each load center, the label will be located on the interior sidewall of the enclosure. The Wiring schematic will state "Box bonding when required" and indicate the location on the Main Neutral Assembly of where to install the green bonding screw. The green bonding screw, is a Form Threading(or self-tapping) screw and will require a small amount of force to get the screw started in the hole of the enclosure.
Installing Neutral Bonding Screw on QO & Homeline Load Centers
Product Line:
QO and Homeline load centers
Environment:
Box Bonding for High Amp, 150A and Above
Cause:
Application
Resolution:
All QO and Homeline load centers that are marked 'Suitable for Use as Service Equipment', will come from the factory with a Green Neutral Bonding Screw, to be installed when the load center is used in a Service Entrance Application.
When a load center is used as Service Equipment, the NEC requires that the neutral shall be bonded to the metal box. The Service Equipment is identified by the fact it includes the first disconnect of the incoming power from the Utility. For a single family house, many times the load center is the main panel, with the main breaker acting as the Service disconnect. In this panel, the green screw is used to bond (fasten) the neutral to the metal box. This is only done in the main panel.
NOTE: Any panels installed downstream of the main panel are called sub-panels, and the neutral in these panels must not be bonded to the box. Since many Load Centers can be used as either the main panel, or as a sub-panel, the green screw is included with the load center to be used in the appropriate installation.
The green screw is also commonly called the "Neutral Bonding Screw", or the "Bonding Screw".
Refer to the Wiring Diagram Label of each load center, the label will be located on the interior sidewall of the enclosure. The Wiring schematic will state "Box bonding when required" and indicate the location on the Main Neutral Assembly of where to install the green bonding screw. The green bonding screw, is a Form Threading(or self-tapping) screw and will require a small amount of force to get the screw started in the hole of the enclosure.
Released for:Schneider Electric Canada
