If I signed a promissory note to purchase a house what state law does it fall in?

The law where the property is located applies. It is a consumer debt. Read the promissory note.

If this is some sort of standard form promissory note, it may have a provision for which state's law controls. If not, if both parties signed the note in California, California law would control, especially if the real property is located in California. Subdivision (f) of California Civil Code section 1788.2 defines "consumer debt" as "money, property or their equivalent, due or owing or alleged to be due or owing from a natural person by reason of a consumer credit transaction." Subdivision (e), in turn, defines "consumer credit transaction" as "a transaction between a natural person and another person in which property, services or money is acquired on credit by that natural person from such other person primarily for personal, family, or household purposes." So, if the note is for the purchase of a personal residence, then it is a consumer debt. If it is for the purchase of a rental property or other commercial building, then it is not a consumer debt.

Purchasing a home is a consumer debt.