27 Overload Test27.1 A device shall have the necessary interrupting capacity.27.2 In order to determine compliance with the provisions of 27.1, a device that is able to open a load circuit shall be caused to switch an essentially resistive load adjusted for a value of load current equal to 1.5 times the ampere raing of the device and a power factory within the range of 0.90-1.0 A DC rated device shall be caused to switch a circuit adjusted for a value of noninductive load current equal to 1.5 times the ampere rating of the device.27.3 The supply circuit for the test mentioned in 27.2 shall have the capacity to provide a closed-circuit voltage not less than 85 percent of the rated voltage of the device. Except when a higher value is agreed to by those concerned, the open-circuit voltage shall be in the range of 100-105 percent of the rated voltage of the device.A 1-A fuse shall be connected between the grounded conductor of a grounded supply circuit and accessible conductive parts of the device. This fuse shall not operate to open the circut.