Stingers are an industry term for an extension cord. They come in 10', 25', and 50' lengths. They are color-coded blue for 25', and red for 50'.

We use SJOOW type insulation with 12 gauge wire for our stingers.

S – Service cord, heavy-duty, flexible cable for industrial and commercial use.

J – Junior service rating, meaning it’s rated for 300 volts (not 600 volts like SOOW).

OO – Oil-resistant insulation (O) and oil-resistant outer jacket (O again).

W – Weather and water resistant, suitable for outdoor and damp locations.

Uses

Stinger Crate on Set

A crate comes with 4-25' and 4-50' stingers. This count fits well and is easy to remember.
When you stage a crate of stingers near a power source or anywhere on set, place the crate on the short side leaving the open side accessible. the short side takes up less floor space.
Place the 4) 25ft stingers on top of the crate, leaving the 4) 50ft stingers inside the crate still. This allows you easy access to both types of stingers without causing a mess.
As you're wrapping stingers and bringing them back to the crate, stack the 25fters on top with the laces out. Place wrapped 50ft stingers inside the crate with the laces facing out.
Only when you have 4 of each type of stinger can you put the 25fters back into the crate. Once the crate is fully loaded, place it on the long side with the open part of the crate facing up. This position states that the crate of stingers is full and is ready to be put away.
Its best to wrap the tie around at least twice and then tie your knot as this will keep it tight.

Stingers should be staged at your power source.

Run the stinger with 90 degree turns and along with other cable.

Twist the stinger as you pull it out to remove kinks.

Run it in a way that does not cross major foot traffic areas.

If you must cover it with rubber matting or use tape as a last resort.

The excess coil of stinger should be at the base of the lamp.

Flip the coil over so that if you stem up it will not flip over your coil.

Stingers should always be run under camera cables

If you are worried about kick outs on stingers that are in line with each other, use the ties to connect the two stingers. do not tie the two stingers into a half hitch.

If you have intermittent connectivity it means you have a loose wire. You can figure this out by bending the stinger at one of the connectors to see if it gains or loses connectivity while energized. Open up the connector while the cable is NOT energized and figure out which wire is loose and tighten it. If the connector looks melted in any way replace it.

You can use the following tools for troubleshooting.

Edison Tester: Patch in the Edison tester into an outlet or connector and it will tell you if it has no ground, if the hot and neutral are reversed, or no power at all.
Multi Meter: Measures voltage and has a continuity tester. Will also measure resistance.

Slightly different connector, but a very similar concept for fixing a stinger. How To Fix A Broken Electrical Cord / Wire