An implantable pulse generator or external trial stimulator for coupling to a lead with a distal end and a proximal end, the lead comprising at least one terminal disposed at the proximal end. The implantable pulse generator comprises a connector for receiving the proximal end of the lead, the connector having at least one contact, and a sensor configured and arranged for detecting electrical connectivity between the implantable pulse generator or external trial stimulator and the lead, the sensor comprising at least one sensor contact, the sensor contact being configured and arranged for electrically coupling to a terminal of the lead and at least one of the contacts of the connector when the lead is fully inserted in the connector and thereby detecting electrical connectivity between the implantable pulse generator or external trial stimulator and the lead.