How long should the break-away brake cable be?

[Sinnettc]

The break away cable on my boat trailer, with an attwood surge brake coupler, is maybe 3 feet long and doesn't have a lot of slack when it's connected to one of the safety chain holes in the hitch. It's short enough that I suspect it would trigger the brakes if the hitch comes off the ball.

The one on my Trail Cruiser TT is much longer and nearly drags on the ground when it's hooked the same way but it's too short to go around the bumper or anything else. Are the brakes supposed to come on if your tongue drops onto the safety chains or is it only supposed to trigger the brakes if the entire thing comes loose? If the former, how do I figure out how long it needs to be to trip the brakes?

Thanks.

[Ole_Man_Dan]

An overlong cable can be threaded thru links of the safety chain and reduce it's length.