Lumin Smart Panel

Installation Error

Most commonly, the installer has not completed the GDC. Ensure that this circuit is receiving 120 volts from a portion of the wiring system that will lose voltage in a grid outage.

Blown Fuse

The inline fuse (see photo below) is tested during manufacturing and so will very rarely be blown upon arrival to the customer. However, abnormal electrical conditions on this circuit will blow the fuse.
To check the integrity of the fuse:

1. Ensure that the GDC circuit is de-energized from the grid source (this is normally done at the GDC overcurrent protection device).
2. Insert a small flathead screwdriver into the nock at the end of the fuse holder.
3. Depress the end of the fuse with the screwdriver and turn 1/4 turn counterclockwise.
4. The fuse holder is spring loaded and once turned in this manner the inner fuse cartridge will partially pop out of the fuse holder.
5. Fully remove the fuse from the fuse holder by hand.
6. Visually examine the clear glass fuse.

It is easy to visually verify whether the metallic fusible link is intact or not. An intact fuse is shown below.

Replacement fuses can be sourced from a variety of online vendors. Use the following search string: "Littelfuse 0313001.HXP FUSE, 3AG, 1A, SLO-BLOW 250VAC". Suitable fuses may also be available locally. Ensure substitute fuses have equivalent specifications: 1-amp, slow-blow, rated for more than 120 volts alternating current. Note that use of replacement fuses that are of a different rating than the original may void Lumin's warranty as it relates to the grid detection components. Replacement fuses may require a different aftermarket fuse holder. Note that direct-current fuses intended for automotive use will not work safely on AC circuits.

Important: The cause of the blown fuse should be determined before replacing the fuse. Failure to do so will likely result in an additional blown fuse. Almost all blown fuses are the result of a shorted GDC circuit. Such a short can occur if the two conductors of this circuit make contact, usually at the translucent yellow GDC relay. One common cause of such a short is connecting the GDC to two ungrounded conductors. The relay is rated for 120 V, not 240 V. Excess voltage can burn out the relay, leading to a short between conductors and short circuit current in excess of the 1-amp rating of the fuse. Anytime a fuse is blown, ensure that the GDC neutral conductor has been connected to neutral and not to a hot/ungrounded conductor.

A less common source of a blown fuse is overvoltage from a nearby lightning strike or other surge event.

If the fuse has been blown, the GDC relay should also be examined for damage. Typical damage will be evident as discoloration in the relay. See photos below of this relay. The housing should be a uniform translucent yellow. The cylinder inside should be a uniform solid blue. Any brown areas indicate a blown relay. An intact relay will make an audible click when voltage is introduced or removed.

Unseated Fuse

In rare cases, usually after installer involvement, the fuse cartridge may be inserted in the fuse holder but not fully seated. This will prevent a complete circuit even if the fuse is intact. A fully-seated fuse is indicated by a fuse cartridge that is flush with the rim of the fuse holder.

Fully-seated	Unseated

Before seating/unseating the fuse, ensure that the GDC circuit is de-energized from the grid source (this is normally done at the GDC overcurrent protection device).

Pulled-Apart GDC Relay

For Lumin Smart Panels manufactured in the second half of 2020, a common issue is GDC wiring that has pulled apart at the GDC relay, often as a result of wire strain during shipping and installation. Note that this is now a rare problem as most of this inventory has already been installed. 

As a result of these issues, Lumin Smart Panels manufactured from late 2020 onward have relay connections that are soldered, not crimped, so this issue is unlikely to occur in more recently manufactured units.

The image below shows the relevant GDC/GVD components. Note that in most documented cases of GDC failures due to the pull-apart issue the relay is zip-tied to the lower left of the cape board instead of the lower right as shown in this photo.

A pulled-apart GDC relay can be easily repaired in the field. The repaired crimp is unlikely to fail as the unit is no longer subject to the same wire jostling experienced during shipping and installation.

1. Gain better access to the relay by removing the cape mounting Phillips screw to which the GDC relay zip tie is secured to (see photo above). Installers should be aware that this is a specialty zip tie with a screw hole; they should avoid cutting this tie if possible.
2. Identify the hot/black and neutral/white GDC conductors that have likely been pulled completely off of the connector pins on the relay. These are terminated in crimp connectors.
3. Identify the polarity of the connector pins. With the relay in its original configuration, with the yellow housing oriented toward the top of the enclosure and the blue cylinder inside the relay oriented to the right, the hot pin is to the front and the neutral pin is to the rear. See the photos below for additional detail.
Original Configuration	Configuration Viewed from Behind/Flipped Over
4. Crimp the wires onto the correct pins using the original crimp connectors, which should still slide over the pins. A crimp can be made via a strong squeeze of needle-nosed pliers or another narrow crimping tool.
5. Close and re-open the Lumin app and ensure that Smart Power Mode appears under Controls. If not, check the integrity of repair crimps and other possible sources of failure in the circuit.
6. Resecure the GDC relay to the cape board using the original screw.

General Grid Detection Circuit Diagnosis

Occasionally, the diagnostic steps above will not isolate a problem and the installer will need to verify if the GDC assembly is functional or not. The following steps can prove GDC functionality, but caution should be taken before using these steps to declare a GDC non-functional. Each of these diagnostics are prone to instrumentation and observation errors.

WARNING: The following diagnostic procedures involve carefully examining electrical components while in an energized state. These procedures are safe when performed with care and an understanding of the dangers. Under no circumstances should the following be performed by an unqualified individual. 

Diagnostic Step 1:

Check the relay to ensure it is closed when grid voltage is present. The yellow translucent GDC relay can be carefully removed from the cape board by removing the mounting screw that penetrates the relay zip tie. Once the relay is free from the cape, it can be manipulated for a better view of the internal mechanisms. Ensure that no conductors become unconnected from the relay while manipulating it for a better view. The relay is normally open. When grid voltage is not present, the contact within the relay will be in the position indicated in Figure 1. When grid voltage is present, the relay will audibly switch to the position indicated in Figure 2. Warning: 120 volts may be present between the 10 AWG black and white wires crimped or soldered to the relay. Use caution to not touch the terminals of these wires or cause multimeter probes to create a short between these conductors.

Figure 1: No Voltage to GDC Relay	Figure 2: Voltage Present on GDC Relay

If the proper operation of the relay is not observed as described in this diagnostic step, skip to Diagnostic Step 3.

Diagnostic Step 2:

If the GDC relay closes in the presence of grid voltage as explained in the previous diagnostic step but Smart Power Mode still does not populate in the Lumin app or if the relay cannot be examined closely enough to determine if the contact is closing, the secondary wiring between the GDC relay and the cape board can be tested for continuity. To do this, trace the small-diameter wires crimped to the relay. Located where this black and red pair are landed on the cape board and disconnect this black connector by depressing the tab and pulling it away from the cape. The female ports of the connector are too small for testing with typical multimeter probes, however, the connector has exposed test points on its long axis (see Figure 3 below). When grid voltage is applied to the relay, a multimeter will indicate continuity between red and black wire connector test points. Note that there will be no voltage when testing this circuit while it is unplugged from the cape board. Touch probes to the two exposed metal test points on the connector as indicated in the figure below and test for connectivity or resistance. Resistance will be dependent on how clean the meter probes are, but should be less than 100 ohms.

Figure 3: GDC Connector Showing Metallic Continuity/Resistance Test Points

Diagnostic Step 3:

If the GDC is not working and the fuse is intact as indicated earlier in this document, the wire nuts between the GDC fuse and the GDC relay can be unscrewed while the GDC is de-energized. Once the wire splices are bare, accessible, and separated so that no arc will form between them, re-energize the GDC. Use a multimeter to ensure there is approximately 120 VAC between the splice on the black wires and the splice on the white wires. If there is not, there is a problem with the wiring on the line (upstream) side of the splices. This may be an issue with the fuse holder or the GDC field wiring. Ensure that the GDC is getting voltage from grid-connected premises wiring.

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