Understanding Mitsubishi Wire Sizes

  March 1, 2017      Jeff Rosenblum


Recently I have been receiving a lot of questions regarding the wire sizes that connect to the indoor units and line set sizes on Mitsubishi equipment. Here is a brief explanation:

  • An M Series 1-to-1 system (1 indoor, 1 outdoor) wire size is 14GA
  • P Series 1-to-1 system is 16GA
  • An M Series Multi-Zone without a branch box is 14GA
  • An M Series with a branch box requires 16GA wire from the indoor head to 
the branch box. It also requires 16/2 stranded shielded wires to be run from the branch box to the outdoor unit. It will also need 14/2 to be run from the branch box to the outdoor unit (this powers the box). This wiring must be followed for proper operation.

The last thing to bring up is the line set sizing. Line set sizes must follow what the indoor unit requires. For example:

If the indoor unit requires 1/4″ – 3/8″ then the line set must be 1/4″ – 3/8″ regardless of the port of the outdoor unit or branch box. If a change in size is needed to connect to the outdoor unit or branch box, we sell adapters to be used at the outdoor unit or branch box.

If you have any questions please feel free to contact the HVAC Technical Support Team.

Jeff Rosenblum 
Technical Support
18 Years Industry Experience
Cell (330) 962-2491
[email protected]