Need a hole in breaker box 1997 Scamp 13

[nigeleccleston]

I'm adding a breaker to hook up to an additional electrical outlet in my 1997 Scamp 13. So I'll need to thread and clamp electrical cable through the wall of the breaker box.
The breaker box is plastic. I can feel a circular line on the left underside of the box but it doesn't break out, which ever side I press it from. Do I need to pull the entire breaker box so I can drill or cut a hole?
Thanks!

[stevebaz]

Loosten it up enough to put a socket with a nut size slightly bigger than the knockout ring and then get a narrow screwdriver and punch around the ring into the socket until you can twist it out with linemans pliers. Of course disconnect power supply before working on the electrical system.

[Joe MacDonald]

if it's a plastic box then it probably has the indent of where one would be, it may break out if you punch around the indent you feel, but that might just break the box. better by far to loosen it enough that you can see the indent clearly, the hole would be the exact size of a 7/8 hole-saw, you could probably twist one in by hand.
I keep an old drill chuck around for working with plastics, then I can control the speed and torque better as it's my hand doing the twisting

Joe

[nigeleccleston]

So I couldn't loosen it. And there wasn't enough space to use stevebaz's suggestion of bracing with a socket. Instead, I threaded a second #14 wire through an existing clamp and everything is working. Thanks!