Here's another experience that is non-industrial, but educational. About 8 years ago I build a large addition on my home. Since then, one thing has led to another and I have never "got around to" installing a furnace. The room is well insulated and relatively warm anyway, so I use two freestanding electric heaters when it gets exceptionally cold. These are the 1200W/1500W type I think
. These are the 1200W/1500W type I think. The first big mistake I made was putting them on the same circuit. (I could have sworn that when I wired the room, I put those two outlets on separate circuits). Not long after that one of the heaters began operating intermittantly. When you wiggled the wall plug the heater fan speed changed, etc. Disassembly of the outlet indicated massive damage to the outlet at the spring connection terminals. The wire was also damaged for a couple of inches. Luckily I had left about six inches of total wire in the box, so I was able to cut off the damaged wire and install a new outlet. In addition, I had to remove all of the other outlets on the circuit and replace them with screw type terminals. I think those outlets were safety approved, but the moral to that story, I think, is don't use outlets with spring connectors. I don't think they can safely carry 20-A. About 6 months after that I was sitting in my room watching TV, with a heater on, and sparks began jumping out of the heater. I reached down and quickly turned it off. Turning the switch off didn't help--it just kept right on throwing sparks until I pulled the plug. Since then I have always unplugged the heaters when they aren't in use. One of the heaters is on a "heavy-duty extension cord". After some period of use, the connectors on both ends of the cord started getting very warm to the touch. I replaced these connectors and the connector on the end of the heater cord and it solved the problem. Ignoring my own initial mistake of using a single-circuit, I would say that my other problems have been a result of poor testing by the safety agency of the spring-type terminal outlets and the low-quality connectors that come on the ends of power cords. Max
