Using common sense and keeping alert is always recommended when suspending heavy objects in the air. Most lighting newbies think C-stands are awesome because they're made of steel, but C-stands are not light stands. If one wants to support a light fixture with steel (always a good choice) then purchase a light stand made of steel—the selection is plentiful. The reference for correct C-stand usage comes from the manufacturers of C-stands, e.g. Avenger:
"Avenger C-stands primarily designed to hold grip products, are an effective way of articulating the item they support using grip heads and arms. Available in a variety of heights and some with detachable colums, the Avenger C-Stands have a fast set up and are made from the best materials available."
You can find a similar statement from Matthews. Alternatively, read about correct C-stand usage and other grip methods from Hollywood professionals like Michael Uva who are legally responsible for keeping a film set safe.
