Nail guns have replaced hammers in wood frame construction. They are powerful, easy to operate and boost productivity for nailing tasks. They are also responsible for an estimated 37,000 emergency room visits each year – 68% of these involve workers and 32% involve consumers.
Puncture wounds to the hands and fingers are most common, but more serious injuries and deaths occur using nail guns. A nail gun can produce nail velocities as high as 1,400 feet per second penetrating stressed concrete up to .4 inches (10 cm).
When nail gun accidents do occur, the injuries are often not reported or given proper medical treatment.
Read the material in each section to find the correct answers to each of the questions. After answering all questions, click the "Check Quiz Answers" button to see your score and a list of missed questions. To correct a question, return to the question, review the material, change your answer, and return to the last section page. Click the "Check Quiz Answers" again to recheck the results.
Do not use the browser's "Back" arrow or "Refresh" button to navigate course section pages. Use the dark tabs above (1.1, 1.2, 1.3, etc.) to review/change missed questions.
Note: Videos and exercises in our courses are for information only and not required to view. Final exam questions will not be derived from the videos. OSHAcademy is not responsible for video content.
Nail gun injuries are common - one study found that 2 out of 5 residential carpenter apprentices experienced a nail gun injury over a four-year period. Nail gun injuries hospitalize more construction workers than any other tool-related injury. Click the button to see the list OSHA has compiled of the most common types of injuries while operating nail guns.
Serious nail gun injuries to the spinal cord, head, neck, eye, internal organs, and bones have been reported. Injuries have resulted in paralysis, blindness, brain damage, bone fractures, and death.
According to NIOSH, there are several common causes (risk factors) for nail gun injuries. Click the button to see how nail gun injuries occur in the workplace.
The most common nail gun injuries occur as a result of unintentional double-fire, blowout, and misses.
A 26-year-old Idaho construction worker died following a nail gun accident in April 2007. He was framing a house when he slipped and fell. His finger was on the contact trigger of the nail gun he was using. The nosepiece hit his head as he fell, driving a 3-inch nail into his skull. The nail injured his brain stem, causing his death. The safety controls on the nail gun were found to be intact. Death and serious injury can occur using nail guns—even when they are working properly.
Nail gun safety starts with understanding the various trigger mechanisms. Let’s take a look at what you need to know.
All nailers rely on two basic controls: a finger trigger and a contact safety tip located on the nose of the gun. Trigger mechanisms can vary based on:
Combining the above variations gives four kinds of triggers. Some nail guns have a selective trigger switch which allows the user to choose among two or more trigger systems.
There are four nail gun trigger types recognized by OSHA. They are:
Each trigger type is described in the next few tabs. We also provide a brief description of how the controls are activated.
This type of trigger fires a nail when the safety contact and trigger are activated in any order. You can push the safety contact tip first and then squeeze the trigger, or you can squeeze the trigger first and then push the safety contact tip.
If the trigger is kept squeezed, a nail will be driven each time the safety contact is pushed in. All nails can be bump fired. This type of trigger is also known as bump trigger, multi-shot trigger, successive trigger, dual-action, touch trip, contact trip, and bottom fire.
Bump firing or bounce nailing is using a nail gun with a contact firing trigger held squeezed and bumping or bouncing the tool along the work piece to fire nails. Red dots in the image show path of motion of the nail gun. Each time the gun contacts the surface, a nail is fired.
When using a contact trigger, there are things you need to remember when using single nails and multiple nails.
The full sequential trigger is always the safest trigger mechanism for the job. It reduces the risk of unintentional nail discharge and double fires. To drive a nail, the worker must first depress the trip against the surface and then pull the trigger.
Use full sequential trigger nailers for placement work where the lumber needs to be held in place by hand. Examples include building walls and nailing blocking, fastening studs to plates and blocks to studs, and installing trusses.
Unintended nail discharge is more likely to lead to a hand or arm injury for placement work compared to flat work, where the lumber does not need to be held in place by hand. Examples of flat work include roofing, sheathing, and subflooring.
When using a full sequential trigger, there are things you need to remember both when using single nails and multiple nails.
You may want to consider restricting inexperienced employees to full sequential trigger nail guns starting out. Some contractors using more than one type of trigger on their jobs color-code the nail guns so that the type of trigger can be readily identified by workers and supervisors.
Like the full sequential trigger, this trigger will only fire a nail when the controls are activated in a certain order. First, the safety contact tip must be pushed into the work piece. Then, the user squeezes the trigger to discharge a nail. To fire a second nail, only the trigger must be released. The safety contact tip can stay pressed into the work piece. Nails cannot be bump fired.
When using a single sequential trigger, there are things you need to remember both when using single nails and multiple nails
Research has identified that the risk of a nail gun injury is twice as high when using a multi-shot contact trigger as when using a single-shot sequential trigger nailer.
Like the contact firing trigger, this trigger will fire a single nail when the safety contact and trigger are activated in any order. A second nail can be fired by releasing the trigger, moving the tool and squeezing the trigger again without releasing the safety contact tip. Note that some manufacturers refer to these triggers as "single sequential triggers," but they are different. The first nail can be bump fired with a single actuation trigger but not with a true single sequential trigger.
When using a single actuation trigger, there are things you need to remember both when using single nails and multiple nails.
Read the material in each section to find the correct answer to each quiz question. After answering all the questions, click on the "Check Quiz Answers" button to grade your quiz and see your score. You will receive a message if you forgot to answer one of the questions. After clicking the button, the questions you missed will be listed below. You can correct any missed questions and check your answers again.