Hello,
I have a number of arduino based sensors and controls deployed around my house to help to monitor and manage electrical power usage. After a recent lightning storm all the arduinos ceased working (either fully blown or the serial communication was taken out). I am keen to understand the mechanism of failure. There is a lightning conductor on the house which is connected to earth.The electrical system is an 230v AC off-grid, island network running at 230v supplied via an SMA sunny island inverter, SMA sunny boy inverters. the DC system is a 48v battery storage circuit with a wind turbine connected. The neutral of the 230v AC system is bonded to the earth. There are are four earth spikes which are all connected.
My guess is that there are two possible causes of failure:
Overflow of charge and earth seepace caused by lightning strikes in the vicinity.
Voltage spikes in the AC caused by a more direct hit.
Some arduinos suffered catastrophic failure but others only suffered failure to the serial communication functionality - probably because they were connected to other arduinos that suffered more catastrophic faiure.
I think that the more probable cause is item 1 above. I am keen to know how to protect against this. i connect the earth on the arduinos to my earth system.
Actually, there is a third reason. All your wiring is acting as antennas and pick up the tremendous RF generates by lightening. The RF covers ALL frequencies and generates many millions of watts of power. Not much you can do to prevent that.
Describe what you call "spikes" you use to ground your system. Are ALL the spikes connected together with large copper wire?
To protect an Arduino from lightning, it should be enclosed in a grounded metal case, and all conductors leading into the case need to be shielded, with the shield connected to ground. Ground, in this case, means Earth ground.
All those serial connections act as antennas, picking up high voltage impulses from the lightning strikes, and those are what fried the MCUs.
All the spikes are connected with large copper wire.
If the arduino is in a metal box which is grounded, there is still the chance that the serial connections will act as antennas. Presumably, the arduinos can still get fried even if the circuits are in a grounded metal box because the serial communication wires will introduce the high voltage impulse. I can't see how to protect against this. Is there a way to introduce some safety circuitry into the communication wires?