What it is: the mid-span injection tee: one feed in, two segment leads, one through leg that continues down the chain. No molded 4-way exists from the vendor, so these are shop built with a junction: 12/3 SOOW, all four legs 18 in, NL4 end on every leg. Build 9: 6 in service + 3 spare. Build ONE first and have Kenny or Chance eyeball it before running the rest.
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
Leg roles
Upper runs at a mid-span column (DSP, USP, AP1, AP2)
feed in from above · one lead to the segment END arriving at the column · one lead to the segment START leaving it · through leg continues down. The two segments never tie together.
Never at end columns - those are 2fers only. Chain drawing: bea.kg3.io/power.