You have the concept for solving the problem,
yotta, but your math is flawed.
Following your suggestion of cutting the 2 x 4 in half, there are two 250 cm pieces, theoretically spanning 31 wires when approaching them from the perpendicular. However, Pat has two legs, and so long as he slowly shuffles his feet, his 74 kg mass is quasi-evenly distributed between both slats, thereby reducing the point load over span to 1.18 kg/wire.
Before anybody says it, yes, if Pat were to approach in fashion parallel to the wires, he'd trip the alarm, but Pat had checked that out.
yotta wins a fuzzy bunny holding a broken calculator.