SPD 600 LED Question- One or two blue lights when operating????

[michaelantinore]

I have installed a number of SPD 600 on SMA inverters over the past few months and have had one blue light on when energized. Today, when energizing an inverter, our SPD 600's had 2 blue led lights illuminated.

Has anyone ran into this?

Is there a difference in the number of lights illuminated based on the inverter, isolated transformers vs. non isolated?

[michaelantinore]

Just found out that SPD's manufactured and marker "Q2 2014" will have one LED when the array is connected? SPD's marked "Q3 2014" or later will have 2 LEDS when connected.

[vtmaps]

Is there a difference in the number of lights illuminated based on the inverter, isolated transformers vs. non isolated?

Welcome to the forum,

The lights only come on if there is a potential (AC or DC) between the conductor and ground. 

If you put the SPD on the neutral wire, and the neutral is bonded to ground somewhere, the LED (for the neutral wire) will not light up.

Does that answer your question?

--vtMaps