I’m also wondering about your house wiring. It sounds like it’s overdue for an upgrade. New, higher-capacity wires; 3-prong safety outlets… it’s a Good Thing.
I once knew someone who had had a housefire due to the freakiest of causes: a window-mounted A/C unit was vibrating, which (according to the investigator who examined the destruction) caused the electrical wiring inside the wall under the A/C to also vibrate, however slightly. Unfortunately that was sufficient to eventually wear away the insulation at one point and spark a fire inside the wall. :eek:
Laser printers are supposed to be especially bad about throwing off ozone. If you’ve got two laser printers in a smallish room, that’s a real health hazard.
It should be pointed out, in the interest of accuracy, that an actual arc is not necessary for the production of ozone. All that is needed is a sufficiently strong electric field between two conductors, which results in what is know as corona discharge. It can be seen in the dark as a faint bluish-purple glow. Corona disharge is responsible for the ozone production of copiers, laser printers and, of course, ozone generators.