Other MidNite Electronics > MidNite SPD (Lightning arrestor)

MSNPD with only one LED shining


I just installed two MNSPD 115's on a 6 string combiner box. One of the 115's has both blue LED's shining, and the other only has one lit.

The combiner has a split bus bar with 3 strings on each leg. The strings are 3 Hyundai 290w panels, maxing out at around 100v. The red wires are each connected to one side of the split bus bar.

Will the MOV varistors work ok if it takes a hit, if only one LED is lit, or is this a sign of a functional problem?

I think I heard that only one LED lights up when it is on DC - both on AC. 
I suppose you could switch the wires and see if they change  how they light up or if it does the same thing .
So not sure why one would have both LED's lit and one has only one if they are wired up the same way.
Are they the same model MNSPD - there was a bit of design change on them over the years - maybe only internal components.


From the Midnite Knowledge Base
 All Categories ยป SPD - Surge Protection Devices
SPD - How do I test the SPD?
We need to verify the SPD is compromised and not something else in the System.

TESTING procedure for the SPD300-DC and SPD600 and SPD115
Using a simple (good) 9 volt battery.
Connect the RED WIRE to the battery POS and the BLACK WIRE to the battery NEG.
Both LEDs should light.

TESTING the SPD300-AC, SPD300-AC/DC and some older version SPD115.
Connect the RED WIRE to the battery POS and the GREEN WIRE to the battery NEG.
A single BLUE LED should light.

Connect the BLACK WIRE to battery NEG and the GREEN WIRE to battery POS.
The other BLUE LED should light.

Help Topics: SPD - Surge Protection Devices

 Last updated Fri, Jan 12 2018 1:02pm

If one works and one doesn't I am assuming its the SPD. Please email me ryan@midnitesolar.com and I will help get you sorted out


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