Test levels are given as the maximum dc charge voltage of the surge generator or current delivered to a tested equipment terminal, and R is the value of the current limit resistor. The current limit resistor may be internal or external to the generator. Note 1: Not applied to equipment designed to be always used with primary protection. For K.20, K.21, and Test 2.1.1, there must be operator agreement and an appropriate internal port test applied (see Table VI). Note 2: Equipment with conductor-to-ground SPDs shall be tested at 1.5 kV instead of 6 kV. Insulated case equipment has 6 kV insulation test. Note 3: With network operator and manufacturer agreement, equipment containing high-current-carrying components that eliminate the need for primary protection shall be tested without primary protection. Testing shall be done with highest-voltage high-current-carrying components. Note 4: Equipment, which is agreed not to use primary protection, shall be tested without primary protection. K.44, 3.1.4. Note 5: Simultaneously applied to all ports. When the equipment has more than eight ports, only eight of the ports are tested. Note 6: Only for equipment that contains high-current-carrying components that eliminate the need for primary protection. Note 7: Apply K.45 port-to-external-port test at the K.20 enhanced level for small telecommunication centers with fewer than 250 lines.

Table I. Lightning tests for ports connected to external symmetric-pair cables.