Garage Door Cables For Torsion Spring System, Extension Spring System, and Safety Cables

Garage Door Cables Are strands of wire twisted together and then bundled and twisted to form cables that are strong enough to lift the garage door. Garage Door cables are the component that actually carry the load of the door when opening and closing. Many things go Into the strength rating for garage door cables. First are the wires themselves typically made of aircraft aluminum or stainless steel to reduce corrosion to the wires. Next are the number of individual wires in each strand and finally the number of strands in each bundle. The heavier the garage door, the stronger the cable should be. Garage door cables have a loop at one end that attaches to the bottom bracket of the garage door and at the opposite end there will be a stop and sometimes a slide stop that attach to the drums(for torsion spring systems). The loops can be simple open loops, loops with spools, or loops with a thimble.

In a torsion spring system the loop of the cable attaches to a stud on the bottom bracket on either side of the garage door. The cable is then run up the height of the garage door and the stop or slide stop if present attaches to the drum. As the door goes up the cable winds itself around the drum and as the door closes the cable unwinds from the drum. The drum is attached to the torsion tube at the top of the garage door opening. In this type of system the torsion spring/s provide the force via the torsion tube through the drums to the cables to open and close the garage door.

In an extension spring system the loop attaches to the stud on the bottom bracket on either side of the garage door and threads up the height of the garage door and through a pulley system that attaches to the extension spring. The cable attaches at the open end back to the garage door track. The other end of the extension spring attaches via a hook to the track support bracket near the ceiling. In this type system the cable running through a series of pulleys and attaching to the extension springs provides the force to open and close the garage door.

Safety cables are only used in extension spring systems. The safety cable run through the extension springs and attach at each end. These safety cables prevent the extension spring from exploding if it breaks or comes loose causing damage to property and or life. Extensions springs can be very dangerous.

*Note: Safety cables are only needed in an extension spring set up.

Garage door cables come in varying lengths depending on the height of the garage door, but as a rule the cables should be 18″ inches longer than the height of the garage door. The easiest way is to purchase cables premade for your garage door height, but you can purchase the parts and make your own cables.

Standard Garage Door Cable Strengths

As stated earlier the strength of garage door cables are based on the number of wires twisted together to form an strand and the number of strands twisted together to form a cable.

A 7X7 cable would have seven wires twisted together to form a strand and seven strands twisted together to form a cable.

A 7X19 cable would have 19 wires twisted together to form a strand and seven strands twisted together to form a cable.

The diameter of the cable is the total size of the cable with all strands twisted together.

The following list gives standard cable sizes and weight ratings:

3/32nd inch 7X7   920 pounds1/8th inch 7X7       1700 pounds

1/8th inch 7X7       2000 pounds

5/32nd inch 7X19   2800 pounds

3/16th inch 7X19   4200 pounds

All of these cables have the strength needed to lift most standard garage doors, but if your door is custom or heavier be sure the cables used are rated to carry the load they are being asked to carry.

When inspecting and servicing your garage door, remember to check your cables for fraying or kinking and replace as necessary. It is also a good idea to apply a thin coat of lubricant to the cables as needed to prolong the life of the cables.