UFC 3 -520-01
June 10, 2002
Figure 11-3. Optimal Installation of Surge Protector Leads Second Example
11-3.1.4 The installation instructions provided by some manufacturers specify that the
surge protector should be installed within 3 meters (10 feet) of the circuit connection
point. This long of a lead length is unacceptable because the allowed let-through
voltage would be too large to protect the downstream equipment. This effect applies to
all parallel surge protectors, regardless of rating and qua lity. Figure 11-4 shows an
example of a surge protector that is located on the other side of a room from the load
center; in this case, the surge protector provides no meaningful protection against
surges. Figure 11-5 shows another poor installation in w hich a safety switch is installed
between the surge protector and the breaker panel. Although the safety switch
application is well-intended, its use adds several feet of cable between the surge
protector and the breaker panel. In summary, the best surge protector will be rendered
useless by installing long leads between it and the circuit connection point.
11-5
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