Just to be clear, I'm not saying "don't buy the BrickWall products". They actually look pretty interesting, although I would like to know how they handle common mode or floating neutral scenarios (these are the reason most surge supressors wire a MOV from hot to ground as well as hot to neutral).
There are, I guess, four main claims for the BrickWall suppressors :
1. By using an LC circuit in front of the surge dumps they are able to reduce the current surges and prevent the rest of the circuitry from failing.
2. By using active circuitry (SCRs and slew-rate sensing trigger circuitry) rather than MOVs they are able to provide more robust protection and to do a better job of minimizing the amount of surge energy passed through to the equipment.
3. By using series capacitors in the surge dumps (see 2) they are again able to limit the amount of current being dumped into neutral.
4. By only focusing on hot-to-neutral surges (the most common) they avoid dumping surge current into ground and the associated problems that ground bounce can cause.
Claim #1 seems valid but I don't think they are the only people using series LCR circuitry these days. They may be running the largest inductors which is definitely a benefit.
Claim #2 is probably true in the sense that MOVs tend to be fairly small and the design doesn't seem to scale up well to "big honkin' MOVs", while "big honkin' SCRs" have been commonplace for decades.
Claim #3 seems valid for short surges but it seems to me that the series caps would also largely eliminate protection from longer surges. I haven't done the math to see if the capacitors would fill up before a corresponding MOV would fry, but I don't think you can store an MOV's worth of joules in a little capacitor
Claim #4 is true but then what DOES happen in the case of a common-mode surge (lightning) or floating neutral scenario ? Most of the reviews I have seen of the BrickWall seem to suggest pairing it with a more conventional MOV suppressor anyways, placing the MOV suppressor after the BrickWall. I suspect this is to pick up the hot-ground MOV protection that BrickWall doesn't believe in
Anyways, they look interesting but unless we understand what they do about common mode surges I wouldn't throw out your MOVs yet.
