zanydroid
Solar Wizard
AC SPDs have many different possible protection modes.AC SPDs they have nothing to do with ground
They can do L-N clamping, L-L clamping, L-G clamping (if not more). The more the merrier, probably. I've seen some claims (but no explanation to back it up) of either L-N or L-G being better than the other ?
And it varies by the type that you get. You can get L-N, L-L-N, L-L-N-G wiring ones. It's like razor blades.
I believe with SPDs there's also redundancy advantage with having multiple, as well as how quickly they can clamp in response to surges coming from various directions.
(Actually I think the same diversity would apply for DC SPD)