Finding a
good breakaway neck lanyard is quite a bit more complicated than most users imagine.
First of all, the 'weak link' part
must be located on the lanyard in such a way that when gravity pulls the light into it's normal hanging position the weak part will be right at the center of the back of your neck or very close to it. Any so-called breakaway lanyard that has the weak link out near the light will be nearly worthless from a safety point of view. It's easy to see that if whatever sucks up your light grabs any slack in the lanyard before straining the weak link to the breaking point it may very well have a death grip on your lanyard
way beyond any point that will break before causing death or serious injury to the user.
Many of the
friction approaches (like heat shrink tubing, for example) are fatally flawed because they are inconsistent. One heat shrink joint may offer just the resistance you wanted while the other may be too lose. One or both of the joints may become too lose as time goes on since the joint is based only on friction. It should also be noted that in many circumstances, loss of your light because of a faulty breakaway link may be just as hazardous as the choking threat of a standard lanyard.
In my experience there are really only two viable approaches to this problem:
- The most straightforward and probably safest tack would be TonkinWarrior's advice -- that would be to make the entire lanyard out of a material that does not have the strength to do great injury in case of a mishap -- like bead chain. I think that general strategy is probably the safest and most fool-resistant.
- Under some very demanding conditions where abrasion and wear are a problem a weak link in a heavier lanyard may be all that will work. In that case a weak link of known strength must be attached in such a way that the joints will not lose much of their strength with time and use. In most cases sewing a weak link of known strength into a heavier lanyard will be very stable over the long haul. Remember that sewing or nearly any means of attaching the link will usually bring the breaking strength of the link below it's normal rating.
Breakaway lanyards should be periodically tested throughout their lives to assure that they are still able to hold your light so it will be there when you need it.
