Can I hook up to a house from a 30A plug to a 15A circuit

As other have said, you can do this but there is a risk of using too much and causing a brown out. What that does is is when voltage drops below 105 volts. Some things are not affected by that low voltage, like a space heater. Many appliances are. Extension cords and hockey puck adapters can be affected. They can over heat and cause fires.

I would get a Kill-A-Watt and not go below 105 volts.