Thomas & Betts Grounding Wedge

No. The Thomas & Betts 3655 series is a grounding wedge, a bronze piece sized to the conduit it bonds, so it is a conduit/raceway bonding part. A mechanical lug-type connector such as the Burndy K2C20 SERVIT POST joins two cables to a flat surface, and the NSi copper C-tap crimps a ground conductor to another conductor. If you are tapping or splicing wire rather than bonding a conduit, one of those is the part you want.

Part 3655, the 2 inch wedge. The sizing follows trade conduit size, so a 2-1/2 inch run takes the 3656 and a 3 inch run takes the 3657. Ordering one size off is the usual mistake here, because the wedge has to seat on the specific size it was made for.

Not interchangeably. The NSi Industries CT series copper C-tap is a 600V compression grounding connector that crimps conductors together in a C-shaped sleeve, so it is a wire-to-wire tap and needs a crimping tool. The Thomas & Betts grounding wedge is a bronze connector sold in 2 inch, 2-1/2 inch, and 3 inch sizes, sized to the element it bonds rather than to a conductor pair. Use the C-tap where you are tapping a ground conductor, and the wedge where the bond is made at a sized fitting.

They solve the bonding problem in different ways. The Thomas & Betts grounding wedge is a bronze grounding connector offered in 2 inch, 2-1/2 inch, and 3 inch sizes, with the wedge driven to make the bond. The Burndy K2C20 SERVIT POST is a mechanical grounding connector configured for 2 cables to flat, so it clamps two conductors to a flat surface rather than wedging into a round sized fitting. Choose by what you are bonding to: a sized round element for the wedge, a flat pad or bus with two cable runs for the SERVIT POST.