MC43 Fusing

Chris Litwin 5 years ago in Master modules / MC4x updated by Ryan 4 years ago 4

The MC43 documentation states to use a single 40A external fuse to protect the module. Is it sufficient to run two single 20A fuses, one on each +BAT connection?

The +BAT is tied inside the module, so if one of the wires were to break or be damaged you would pull all the current to handle the outputs through a single 20 A fuse. We prefer the 40 A fuse close to the module and then a Y splice to the +BAT pins.

Can I assume this is also true for the XC43?


I'd say that two separate 20 A fuses could be preferable. 40 A is the maximum specified for the MC4x, but one other aspect to consider is the wire gauge. 

As Ken points out, if you do split it up in two 20 A fused wires, trobleshooting a cut wire could be tricky, as that would blow the fuse on the undamaged wire.