Has anyone any experience of using a product called Plug-in Pest-Free? It's a small box that plugs into a 13-amp socket and is claimed to drive away rodents. To quote from
"The PestFree Plug is built around a computer chip which is ... programmed to alter the electromagnetic field, which is produced by the mains electricity as it flows around your wiring. This is normally 50Hz which is perfectly acceptable to Rats, Mice etc. and Housebound insects such as cockroaches. The change which Pest Free Plug produces in the electromagnetic frequency disturbs the equilibrium of all household pests to such an extent that they no longer EAT or BREED and, most importantly, try to get away from this disturbance as quickly as possible."
It is claimed to have no effect on other electrical equipment.
The implication of the sentence which mentions 50Hz is that it alters the mains frequency!
Is this (a) possible, and (b) safe for other equipment? And (c) does it work?