He told me I didn't know what I was talking about and that there was no way I could be certain what was happening as I insisted. I told him that they could leave it the way it was then and I would just sue them for my computer network, fridge, a/c etc when they were damaged. I said that my Fluke recording voltmeter would probably pass for evidence of the spikes.
Back in the early 80's I was the designer of some multiprocessor special-purpose business computers which the company sold in the $100K-250K range. We sold one to a Manhattan typesetting shop and they had it installed in the middle of nowhere (Arkville, NY) because the data entry operators would work for far less out there. Almost immediately there were complaints about lockups and errors. This typesetting shop had been using paper tape equipment with transistor logic and beefy linear power supplies. Microprocessors with 35ns static memory chips and switching power supplies couldn't cope with the wild spikes and sags in power.
I went up there with the owner of the company and a leased Dranetz power quality meter. We set it up in the late afternoon and went out for a leisurely dinner. When we came back, all of the adding-machine tape from the Dranetz was coiled on the floor, reporting continuous errors. The Dranetz itself was catatonic and had to be sent back to the manufacturer to be rebuilt.
My computer was moved to Manhattan where it ran for quite a few years. The owner of the typesetting shop cancelled the service contract "to save money". A few years later, I get a panic call from him that the system isn't working. I go over there and find a solid inch of dust and paper shards blocking the air filter. Fearing the worst, I opened the top of the card cage and discovered that it had gotten so hot in there that the gold caps on the RAM chips had un-melted from the solder and fallen down to the bottom of the memory array.
I was able to reconfigure the system from 8 entry stations plus the high-speed transmitter to the typesetting machine, down to 2 stations plus the transmitter.
This system was used to typeset the first editions of a number of books you may have heard of:
"The Islamic Bomb" - a NY Times book and the first one completely done on the system I designed.
"License Renewed" - the first post-Fleming Bond novel by John Gardner
"2010: Odyssey Two" - while the liner notes state that the text was transmitted electronically from Sri Lanka to New York, that went to the publisher and was printed out. That copy was re-entered by hand on the system I designed after the copy was marked up with typesetting cues.