Owner`s manual

21 | P a g e
DC GFP (Ground Fault Protection)
The Classic has internal ground fault protection (GFP) built in. Since 2008 the NEC requires a DC-GFP
on all PV systems in the USA. The built in DC-GFP eliminates the need to purchase and install an
external DC-GFP. If the internal grounding jumper is installed in a Classic, the battery negative and DC
source negative must not be connected to the system grounding conductor anywhere in the system.
Grounding of these circuits will defeat the GFP function. In a network with multiple Classics, all
Classics must have the internal grounding jumper installed and GFP enabled. The factory setting will
make a DC negative to System Ground connection in the Classic charge controller. The GFP function
will need to be disabled for Positive ground or an ungrounded DC system.
Jumper Off (Ground Fault non Active) Jumper On (Ground Fault active)
The Ground fault device is simple to understand and use. The Classic DC-GFP works a bit different
than others. It detects a fault between battery/PV negative and earth ground just like the breaker DC-
GFP system. The difference with the Classic is that it turns off the charge ability and sounds a loud
warning when a ground fault is detected. This is different than disconnecting the PV plus circuit. This
trick of turning off was first pioneered by another charge control company as an alternative to a $100
external circuit breaker assembly. The Classic’s system consists of a PTC that is between the Negative
and Ground internally in the Classic. A PTC is basically a type of resistor with a 1 ohm value that when
loaded to three quarters of an amp will heat up and go to a very high resistance looking like an open
circuit. One of the 3 Classic microprocessors watches the PTC and when it sees a high resistance it will
disable the Classic. The ground fault device will then require a manual reset. The PTC is self-healing
though so there are no fuses to change. This method meets the requirement for DC ground fault
protection in the National Electric Code.
To disable the internal Ground Fault Protection function, the jumper labeled GFP needs to be removed,
and the GFP function must be disabled in the TWEAKS menu. See section below for instructions.
To reset the internal GFP function after detection has occurred; fix the actual ground fault, then turn
OFF the Classic and turn it back ON. Do this by turning the external battery breaker to OFF position
and then to ON position.
Disabling GFP
The GFP feature should only be disabled to operate the Classic in an ungrounded power system or in
systems where GFP is not required.
 Press Main Menu