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Classic SL owner’s manual REV E 2056
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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 connected in Follow Me,
only one Classic should have its internal grounding jumper installed and all should have 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 12
The Ground fault device is simple to understand and use. 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. The Classic’s system
consists of a PTC that is between the Negative and Ground internally in the Classic. A PTC is basically a
self-healing fuse that will open when current exceeds its rating and reclose when current is dropped below
its rating. The Classic will monitor this PTC and disable the charging when it senses it go open. When the
fault is cleared the Classic will restore charging.
To disable the internal Ground Fault Protection function, the jumper labeled GFP needs to be removed and
the GFP function needs to be disabled in the TWEAKS menu. See “Disabling GFP” 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.
Figure 11