I would guess that 'breakaway' refers to something that would unplug when the pole is knocked over.
I think the Bussman in-line fuseholders I've been using are called "HEG." They use fuses such as KTK (fast acting) and FNQ (time delay).
I strongly recommend using time-delay type fuses, especially with HID lights.
The one drawback to the fuseholders is that it is difficult to get a good crimp. If the fixtures are not already wired with stranded wire, I suggest re-wiring them - or at least make pigtails.
