UFC 3 -520-01
June 10, 2002
11-3.2.2 Verify with the manufacturer the minimum required breaker size to ensure
proper surge protector performance. This is important because breaker instantaneous
trip units also respond to surge currents. Testing by one manufacturer determined that
a 60 ampere breaker can usually withstand a 65,000 a mpere 8/20 surge. A 30-ampere
rated breaker tended to trip above a 25,000 ampere surge. Based on the above results,
lower-rated breakers can be expected to trip at lower current levels. For sub -panels, a
30-ampere minimum breaker should be used to minimize the likelihood of breaker
tripping during a surge event. This is important because breaker tripping removes the
surge protector from the circuit, thereby disabling surge protection for subsequent
surges.
11-3.2.3 Some surge protectors have been liste d based on the connection to an
upstream breaker. Review the manufacturer's installation instructions to determine if
special electrical connection requirements apply.
11-3.2.4 If a spare breaker is not available, it is acceptable to connect to the load side
of an existing used breaker. Parallel surge protectors are passive devices that draw a
negligible current during operation.
11-3.3
Grounding. Verify that the surge protector is properly grounded. Without a
low impedance ground, the surge protector cannot effectively shunt the surge to ground.
Also, surge protection will be less effective if the entire facility does not have a low
impedance grounding system.
11-3.4
Acceptance Tests. Perform the following checks :
11-3.4.1 Inspect for physical damage and compare nameplate data with drawings and
specifications.
11-3.4.2 Verify that the surge protector rating is appropriate for the voltage (this is a
common error).
11-3.4.3 Inspect for proper mounting and adequate clearances.
11-3.4.4 Verify that the installation achieves the minimum possible lead lengths.
Inspect the wiring for loops or sharp bends that add to the overall inductance.
11-3.4.5 Check tightness of connections by using a calibrated torque wrench. Refer to
the manufacturer's instruc tions or Table 10-1 of International Electrical Testing
Association (NETA) ATS, Acceptance Testing Specifications for Electrical Power
11-3.4.6 Check the ground lead on each device for indivi dual attachment to the ground
bus or ground electrode.
11-3.4.7 Perform insulation resistance tests in accordance with the manufacturer's
instructions.
11-7
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