Manual

20 | 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.

Figure 2.1

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 simply turns off 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