There are wires connecting the House Shunt to the Battery, they just are not "twisted" ... the manual strongly recommends twisted pair cable. The Manuals also boldly states all load grounds not be connected on the battery side of the Shunt. And, no other wires connected to the Battery NEG other than the wire to the Shunt. That's not the case with my install and I suspect as you confirm why I am having trouble with the House readings. I will redo the wiring, probably replace with twisted wire for the run from the Shunt to the BAT (it is a long run, presently bundled with a bunch of other cable through the bilge) and see what happens ! Cheers, John