In the US as was stated you have to have a minimum of $25,000 in your account to be a day trader. As a day trader you can trade up to four times the maintenance margin excess in the account as of the close of business of the previous day, go over and you're in trouble and will recieve a margin call even if you are flat and have all cash in your account.
In response to your poll, it is a violation, but you are expected to know the rules so it is not a 'good faith violation' just a violation.
