"I purchased a whole system that included an ETA power conditioner rated 20 amperes. The plug will not plug into a standard wall outlet because one of the pins is rotated 90 degrees. My house and almost every house on the planet is set up for 15 ampere plugs and I assume it is not a good idea to just replace the plug with a 15 amp version. What should I do to use it?"

Well, hold on a minute. Before someone accuses us of being too colloquial, let me remind you that nowhere near every house on the planet has 15 amp service. That said, you can assume most houses in the U.S. (our target audience) do. You are correct that a 20 amp plug has one pin turned sideways. This is done specifically to keep them from being inserted into a 15 amp plug. You can buy 20 amp wall outlets. They will accept both 15 and 20 amp plugs. You can recognize those by observing that one of the slots looks more like a sideways "T," which is how they accommodate both types. Of course, the reason you have a 15 amp plug is almost certainly because it is connected to a 15 amp circuit breaker and probably, but not necessarily, because the wiring between them is only rated at 15 amps. This leads us to our first possible solution.

Before we go on, please be advised that we are not electrical engineers and do not know the electrical and fire codes covering your geographic area. Anything we tell you should not be attempted unless you know what you are doing and/or consult with an electrician. We are not responsible for... blah, blah, blah. Okay?

If you can determine that the house wiring in question is capable of handling a 20 amp load you can probably just replace the circuit breaker and wall outlet to accommodate your power conditioner, This is the best solution.