I've seen multiple sources that seem to indicate that one MUST keep his sideburns to either

1. The bottom of the ear
2. The bottom of the ear cartilage
3. To the jaw bone, around the middle of the ear.

When looking this up online, I came across [this psak halacha from R' Abadi](http://kashrut.org/forum/viewpost.asp?mid=6125&highlight=payos), in which he indicates that one who shaves with an electric shaver need not worry about any of this and only needs to leave a few rows of hair remaining in the payos area.

Is this a valid option? Is the practice to keep the sideburns long, as most yeshivishe people do, just a chumra?