I ordered Posi-Tap wire connectors to attach my feeders to my bus wires.
I have two buses: the DCC Bus is 12 ga. stranded wire; the Lighting Bus is 14 ga. stranded wire. So I ordered Posi-Tap connectors ZRTL 643-30 (black) which says it taps 12-18 ga. wires & ZRTL 605-30 (blue) which says it taps 14-18 ga. wires. They are too small to fit the intended wires. The 12 ga. (black) connectors only work with 14 ga. or smaller wire. The 14 ga. (blue) connectors only fit wires 16 ga. or smaller.
So the advice is to buy the connectors one size larger than what you need. I’ll keep the black connectors for my 14 ga. lighting bus and I’m trying to return the blue connectors and instead get the yellow ones which say the fit 10-12 ga wires.