The device must be reliably grounded to meet protective equipment grounding requirements. The surface-mounted case is grounded using the bolt and nut, appropriately marked, as the ground connection. The flush-mounted case must be grounded in the area of the rear sidepieces at the location provided.

The bracket is marked with the protective ground symbol:

The cross-section of the ground conductor must conform to applicable national standards. A minimum cross section of 2.5 mm² (≤ AWG12) is required.

In addition, a protective ground connection at the terminal contact on the power supply module (identified by the letters “PE” on the terminal connection diagram) is also required for proper operation of the device. The cross-section of this ground conductor must also conform to applicable national standards. A minimum cross section of 1.5 mm² (US: AWG14 or thicker) is required.

If a detachable HMI is installed, a further protective conductor (ground/earth) of at least 1.5 mm² (US: AWG14 or thicker) must be connected to the DHMI protective conductor terminal to link the DHMI and the main relay case; these must be located within the same substation.

All grounding connections must be low-inductance, i.e. it must be kept as short as possible.

The protective conductor (earth) must always be connected to the protective grounding conductor terminal in order to guarantee the safety given by this set-up.