This might seem as obvious as warning people not to pressure wash a lemon meringue pie, but people do it anyway. You just don’t hear much about it because they no longer have power in their homes and so can’t complain about it on Reddit. Okay, maybe it’s not that bad, but it’s still not a good idea.
Electric meter enclosures have a NEMA 3R rating, which means they provide some degree of protection against the ingress of rain. How much protection? In testing, these boxes are subjected to water spray at 5 psi. The worst consumer pressure washer will deliver 400 times that much pressure, and the box manufacturer makes no claims about keeping water out at that pressure. It’s not just about meters, either. Other outside electrical enclosures, like disconnects you might use for HVAC and other equipment, have a similar water-resistant (but not watertight or waterproof) rating. And in spite of being described by the National Electric Code as “weatherproof,” outdoor outlets admit water pretty easily, especially if they’re in use (meaning an electric cord is plugged in, preventing the enclosure’s cover from closing). It matters because water can damage electrical components inside of these enclosures, and certainly will cause short-circuits and provide an unexpected path for water to reach you.