RFI Shielding

Projects General Guidance
1

I would think this would have come up before, but unfortunately, searches for "RFI Shielding" return a bunch of results for "RFID" and "shields". Anyhow, how resistant to RFI interference is the ATMega328? How about a standard Arduino board? How about a Arduino main board with a SPI based shield (Ethernet shield for example)?

I'm thinking particularly of two scenarios: 1) when the arduino operating in close proximity to AC power wires that may have a 50-60Hz AC signal on them along with all the various other signals the wires may pick up and 2) when the arduino is close to communication equipment like CB or ham radios.

2

Like any piece of electronic equipment the arduino can be upset by radio frequency interference if you give it enough.
This is not normally a problem with mains. With RF transmitters it could be given enough RF power and a small distance.
What do you want to do?