I've been experimenting with a battery powered PEA. It is the smallest unit of the three sizes available.
So far, I like it best around AC devices such as line conditioners. I get the most effect there, so far. I have not tried it inside components. Second strongest effect is over the inlet of components, close to the IEC inlet. Over power cord plugs is about the same as the IEC inlets.
One of my PLCs has the Pulse Gen inside, which works fine, and is further improved by the PEA over an unused outlet. Over the metal has less effect.
I plan to buy the middle sized PEA, AC powered, and place it over my Synergistic Research Powercell. The Powercell is made of hard plastic and should let in the radiated field of the PEA. One in the breaker panel will be worth a try.
Remember: The small and medium PEA units fire downward.