@joeyfox85 They're a little more expensive but you can find box fans with a ground (three prong) such as Air King. Some reasonably priced commercial HEPA may have a ground connection, not sure.
@joeyfox85 它们稍微贵一点，但您可以找到带接地（三爪）的箱式风扇，例如 Air King。一些价格合理的商业 HEPA 可能有接地连接，不确定。