settings should cause a door to stop or reverse on encountering more than approximately 20 lbs (9.07 kg) of resistance. Safety eyes should be installed a maximum of six inches above the ground. Many garage door injuries, and nearly all garage door-related property damage, can be avoided by following these precautions. Certain parts, especially springs, cables, bottom brackets, and spring anchor plates, are under extreme tension. Injuries can occur if parts under tension are removed. Extension spring systems should always be restrained by a safety cable that runs through the middle of the spring, tying off to a solid point at the rear and front of the horizontal door track. The safety cable prevents hazards to bystanders when a spring, pulley, or cable breaks under tension and makes the system quite safe. Torsion spring systems can be very dangerous as they are always under tension and release energy when the spring fails. Serious injury or death can be caused by the projectile pieces of a failed torsion spring. Many people have been injured or killed trying to adjust torsion springs, and special training and procedures are required to safely adjust a torsion spring, it is a job for a professional not a homeowner or DIYer. References External links American inventions Doors Garages (residential)