So, I just recently received this 2903-9001 light plate, and it came along with this diode that I’m not entirely sure what kind of diode it is, or what it is used for. I’m guessing it’s a “polarized diode” from the pictures I’m seeing.
The question is do I need this diode? I ordered a replacement light bulb that is arriving supposedly Friday, and I wanted to know if this diode is crucial for function of the light plate, or if I don’t need the diode and I can just leave it in my toolbox for “spare parts”.
Anybody got an answer? Fairly new to electronics, and I just started learning btw :lol:. Help would be appreciated if possible. I hope I’m explaining this correctly. If not, then sorry about that
See pictures below for light plate and diode:
Whether the diode is necessary depends on how you are going to use the light plate. The diode was added so the light could be connected to a reverse polarity NAC. It prevents the supervision voltage from going through the light bulb which would cause a short on the supervised circuit. If you connect it to a reverse polarity NAC, you need the diode. If connected to a circuit that is not supervised the diode is not needed.
Interesting that the diode is connected to a red wire. A device having a red and black wires usually means it is already polarized.
[quote="Retired STR-SG" post_id=80829 time=1528909997 user_id=3047]
Whether the diode is necessary depends on how you are going to use the light plate. The diode was added so the light could be connected to a reverse polarity NAC. It prevents the supervision voltage from going through the light bulb which would cause a short on the supervised circuit. If you connect it to a reverse polarity NAC, you need the diode. If connected to a circuit that is not supervised the diode is not needed.
Interesting that the diode is connected to a red wire. A device having a red and black wires usually means it is already polarized.
[/quote]
Ah okay. That’s what I was initially thinking 
. The light plate itself has a white wire (+) and black wire (-). Plus the device itself required 24 volts DC, not AC. I’m running my system on regular batteries, so the diode is not needed.
Good. I’ll hold on to the diode for now. Least now I can confirm it IS indeed a polarity diode. Will only need to use it for a FACP that has a reversed polarity NAC.
Thanks for that 
