What it is: the straight through jumper for the bottom run at END columns: the tee chain's through leg lands on it and it drops the last 5 ft 5 in (assumed) to the final run. 12/3 SOOW, 6 ft 0 in cut, straight through pin to pin, NL4 male one end and NL4 female the other. Build 6: 3 in service + 3 spare.
Wire map — POWER ONLY, all legs common conductor to conductor
Conductor (verify at bench)
NL4 pin
Function
Black
1+
+24V leg 1
Red
2+
+24V leg 2
White
1−
shared GND (V−)
—
2−
EMPTY, capped and labeled
Where it goes
Position
Connection
DS end column · US end column · AP3
2fer through leg (above) → this jumper → NL4 joint at the last run's segment end
Do not confuse with rope jumpers: this is a power-map cable (black 1+, red 2+, white 1−), not the NL4 SPI rope map. GOLD tape (custom length).