Working with 3M Mini-Clamp Connectors

This post describes how to prepare wire and crimp the 3M Mini-Clamp connectors to it. Tools needed are a pair of slip joint or channel lock style pliers, wire cutters (or sharp scissors) and a wire stripper or utility knife.

Mini-Clamp II Series 371 Plugs part # 3M 37104-A165-00E. These are the connectors Firefly/Spyder uses for all of their drop cable connections. Easily crimps with a pair of pliers. Available from many sources including Firefly Integrations in Middlebury, IN. Digi-Key is another supplier that offers reasonably priced USPS first class shipping for small quantity lightweight items like this. I suggest ordering extra of these for future projects – or – in case you make a wiring mistake. Once crimped I do not believe they can be reused (although I never tried to resurrect one).



I really like these connectors. They are much less complex than other connector styles, require no special tools to crimp and are easy to work with. RV-C does not specify any connector requirements, however these are perfectly suited to the job. This connector style has been adopted by Spyder/Firefly and is used on all their equipment, plus some other OEM suppliers are using them as well, such as Garnet.

The connectors, as well as “official” RV-C drop cable are available from Firefly Integrations in Middlebury, Indiana. The will be happy to sell you some. From my last purchase in 2016 they charged me $0.26/ft for the cable and $2.50 for the connectors. The connectors can also be ordered from several internet sources, search on the 3M part numbers in the diagram above. I know of no other source for the “official” RV-C drop cable however CAT-5 or CAT-6 can be substituted as long as it is 20, 22 or 24 gauge, stranded and unshielded. Simply cut off the two unused pairs.


  1. Strip 1 to 1.5″ of the outer cable sheath to expose the conductors.

  2. Generally arrange the wires in the correct order. Starting at the clip with the blue side up the color order is Red/White/Blue/Black.
  3. Grasp the 4 exposed conductors and while maintaining the proper color order, align them closely together. The lengths probably won’t be even, so trim the ends so they are all flush.

  4. Insert them into the wire ports in the blue plastic being careful to maintain the proper color order starting with Red closest to the clip (pin 1).
  5. Make sure all 4 conductors go all the way in.
  6. Now while holding the wires firmly in place, squeeze the blue crimp area with a pair of pliers. Slip joint pliers or channel locks work best because they provide a more even squeeze. Even so, it’s not a bad idea to rotate the pliers position 180 degrees and squeeze from the other side to ensure an even crimp.
  7. Before crimping:
    After crimpling:




2 Comments to Working with 3M Mini-Clamp Connectors

  1. […] Working with 3M Mini-Clamp Connectors […]

  2. […] Once crimped I do not believe they can be reused (although I never tried to resurrect one). See this post for instructions on crimping these […]

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