Easy to use those caps, place inside each plugtop as IS capacitors. Will do a lot to reduce mains noise. I bought a whole box ( 2000 units) of class X2 0.22uF 250VAC capacitors on auction once, for about $1. Been using them for that, and there are a few motors where the capacitors failed that have 20 or so in parallel inside as replacements.
As well I bought 2 boxes of zener diodes, been using them as signal diodes for years, still have not made much of a dent on the 40k of diodes. 12V 400mW and 24V 400mW zeners I now never buy. I was asked for some 13V ones, so gave a box and told them to use 2 in series to increase the voltage by 1V2, even did a quick demo there and then with a PSU, diodes and a random resistor using a DMM to show how.