Well, I FINALLY got around to ordering a Greenwave DE meter and 15 filters. They cost a small fortune since the 230V international version is only available from their web site, and they're $45 a piece - plus shipping + VAT + customs fees!
The first thing I did was measure outlets all around the chateau. Well... That was an eyeopener.
Most readings were about 200-300, with some hotspots about 500-700 where there are lots of puters. But the top 3 measurements were:
1. Behind Laura's desk: 2000+ (IOW, the meter went off the scale!!!!)
2. In front of Iza's desk: 1400
3. Next to Ark's side of their bed: 900
So, first thing I did was install 3 filters at the breaker panel where the power enters the house (in 3 new outlets - one for each of the 3 phases of AC). I noticed that one of the filters sparked when I plugged it in, and they were all buzzing rather nicely (some more than others).
Then I went around plugging in filters and trying to reduce the readings as much as possible in the nasty areas. Of the Top 3 Winners above, all readings are now down around 60, which is a HUGE reduction. I also noted that while they say to get readings down to as low as 25, the GW meter actually reports "Low Noise" when the reading is 100 or lower. That seems more reasonable anyway, because the "balloon effect" as LQB calls it is a real pain to deal with: lower a reading here, and it spikes over there! It's like playing whack-a-mole.
After the remaining 12 filters were installed, the buzz at the 3 filters by the breaker panel is almost 0 now.
Ark discovered that the dimmers in their room were VERY noisy. Interestingly enough, I have an expensive Legrand dimmer that's electronic and even compensates for different types of bulbs (using it with LEDs), and it is actually very quiet in terms of DE noise produced.
I'm not sure what produced the crazy-high amounts of noise in the Top 3 locations, though. It wasn't anything specific plugged in, so there is something else at work that makes those points particularly nasty. Wiring errors shouldn't be a factor because I did the wiring myself in those locations - so no shared neutrals or anything like that.
I'm still not totally happy with readings in some rooms, so I thought I might need more filters. I've shifted filters around to reduce the higher readings here in our downstairs office, and upstairs in L&A's rooms since we spend the most time in those locations. But some bedrooms are still 120 or so, and I'd like to get that lowered. Obviously, sitting at a puter for hours and hours when the level is 560 is probably more exposure than sleeping where it's 120. And some areas (like the Lodge) still have highish readings and no filters.
But I'm not going to pay $1k for another 15 filters. So, I decided to build my own.
This is the inside of a US Stetzer filter from some years ago that I found on YT:
The 256K single cap is 25uF. That resistor as far as I can tell is totally the wrong size for safely discharging that size of cap when the filter is unplugged. Oh well!
So then I took apart one of our 230V GW filters and the following is what's inside:
Note that the above circuit would simplify to just a single 24.7uF cap and a 111k resistor, both across live/neutral. DONE!
As with the older US Stetzer version, there is about 24.7uF of capacitance in the form of 3 MKP62 305V X2 caps across live/neutral. There are also 2 resistors that add up to 111k of resistance to discharge the caps (1/2 W each, and they're actually 222k, I think - close enough). And finally there are two 220pF ceramic single-layer caps between ground-neutral and ground-live. I measured everything just to be sure, disconnecting caps and stuff so I could get accurate readings.
Well, alrighty then!
I did some calculations, and the cap values actually make sense to me when you consider the capacitance, charge/discharge time, risetime of the noise frequencies, and the max current the filters are rated at (15A).
How I think it works: The caps resist a change in voltage. So, when there's a noisy AC sine wave (dirty electricity), you get higher-frequency spikes or dips above or below the nice clean sine wave. IOW, the sine wave looks jaggedy.
If you have a negative V spike, the cap sources current to bring the voltage back up to it's proper smooth level. If you have a positive spike, the cap sinks current to bring it back down. If you don't have enough filters, the cap becomes saturated. In that case, it could source but not sink current. I think...
The two teeny blue ceramic 220pF caps connect to ground must just dump higher-frequency noise to ground or something? They certainly can't sink/source much current like the big honkin' metalized polypropylene EMI caps can.
Anyway, I managed to hop on AliExpress and find:
1. Power Enhancer Save Energy gizmos for $4 each (I need the box with plug)
2. UK -> EU plug adapters (since the 'Energy Savers' are UK plugs w/ground)
3. A bunch of 8.2uF caps ( 3 x 8.2 = 24.6uF)
4. Some 220k 2W resistors (the 0.5W ones are a bit undersized for my taste)
5. Bunch of 220pF ceramic caps
The CassWave filters will look like this:
When it all arrives from China, I will assemble a test filter and see what happens. Total per-unit part cost: $8 a filter!
I wish I would have bit the bullet and done this years ago...