DC panel meter uncertain of the wiring. Hoping for some suggestions

[golash]

Hi
I have this panel meter and I`m uncertain from the diagram which wires go the load. And what
wires power the panel meter`s electronics.  It seems the meter has 3 wires but the pic shows 4 wires.



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[TimFox]

You apply DC supply voltage for the meter electronics between the two wires on the right.  The negative terminal on the power supply (battery or whatever) is common to the negative terminal of the measurement voltage.
The voltage being measured is applied between the two wires on the left.  Again, note that the negative terminal is common to the power supply negative, which normally would be grounded external to the meter.

[Seekonk]

Just make sure you don't power it with more than 28V.   I will often  source the positive power through a resistor if more than 12V to drop the voltage down and prevent line spikes from damaging the meter.  100 ohms is a good start and place a 100uf or greater at the meters red and black wires for filtering.

The current meters are trickier to install as they sense current in the negative lead for convenience of measuring low side voltage and sometimes it isn't easy to isolate common.