Fall Protection Cable

Pretension will reduce sag but will not "take the sag out of the cable" as you stated. Tension in the cable can only be calculated by considering the magnitude of the sag.

Substituting a pipe or a rod for the cable is not a good idea either. Before it can act as a tension member, it has to yield in flexure in order to create a sag.

Why don't you use a beam capable of carrying the vertical loads in bending? That way, you do not need to provide large horizontal restraint at the ends.

Good point about the yield. There is actually a beam directly above this capable of supporting the load, the workers like the cable to be only supported at the ends so they don't have to unhook and reattach between the supports.

If you have a beam capable of supporting the load, why not attach a sliding anchorage device such as shown below?

There is a liner panel attached to the bottom flange of the beams. There is also equipment suspended from the beams by support hangers so a beam and trolley system won't work that well. I think a beam suspended below the other beam may be the best way.

I believe you are correct.

I am not very familiar with Cabe you mentioned above,but I know a kind of Cabe,it is Network cable,Internet speeds up to hundreds megabyte。This website (www.stonecrusher.cn ) used Network cable,browsing speed is very quickly.

Hi koala716,

Welcome and I wish you luck! This is a great site, enjoy yourself.

This is meant in the kindest way.

You are on totally the wrong track here. The OP (Original Poster) is referring to a physical restraint not an electronic safety mechanism, OK?

Take care and happy new year.

Guru us right that you can never take all the sag out. It can be awfully small with sufficient (lots of) tension, but never all of it. What's wrong with letting it sag a bit?

You say the cable is for fall protection, which I take to mean arresting a fall before it goes too far. However, you have not mentioned the weight of the falling object which the cable tension would also have to support. Even worse is the impact load as the falling object is stopped.

Don't forget that whatever the cable ends are attached to also has to support this load.

OSHA requires to take into consideration 310lbs for a person and tools he may be using with a maximum fall of 6'. OSHA requires a fall protection to be designed for a 5,000lb load or 3600 lb if it is certified. I've calculated the load to be about 3700lbs for a 310lb object falling the 6' distance. It can sag a little that's not the problem; it only takes about 810lbs of pretension to take the sag out. We want the cable to stay near where the person is working. If you don't take the sag out the attachment point it could slide to the lower point.

Hi becoleman3,

Take a look at these search sites. They may well help in your predicament.

fall+protection+cable

Take care and happy new year.

Very interesting thread.

My first question; why design this when there are systems in the market? Search horizontal lifelines (North Safety, for example). Also, the user attached should be wearing a harness with an energy-absorbing lanyard. These energy absorbers will limit the forces (in the vertical direction) to 900lbs or less. Also, the horizontal cable should have its own energy absorber at its attachment point.

I wouldn't re-invent the wheel when workers lives are at stake. There are products out there specifically for this applicatios.

Cheers.