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hazards

Nail Gun Hazards

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.

Check out this short audio clip by Dan Clark of the theSafetyBrief.com with help to keep nail gunners from getting an injury.

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 refresh these pages or you'll have to answer all questions again.

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.

1. What is the most common nail-gun injury?

a. Electric shock
b. Puncture wound
c. Struck by flying object
d. Muscle strain

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Updated 5/28/2021

Likelihood of Injuries

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.

  • Hands and fingers: More than half of reported nail gun injuries are to the hand and fingers. One quarter of these hand injuries involve structural damage to tendons, joints, nerves, and bones.
  • Legs: After hands, the next most often injured are the leg, knee, thigh, foot, and toes.
  • Arms, neck, head, and trunk: Less common are injuries to the forearm or wrist, head and neck, and trunk.

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.

Nail Gun Injuries-Graphic
(Click to play video)

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.

  • Unintentional fire: If the trigger is pulled on a single contact or actuation trigger and you accidentally knock a person or material the gun may discharge the nail.
  • Knocking the safety contact: Unintentional fire due to knocking the safety contact with the trigger squeezed.
  • Accidental double fire: A double-fire may occur if you push too hard on a contact trigger nailer, or are nailing in an awkward spot. The second may come out too fast for you to react.
  • Nailing through wood/materials: The nail may come out the other side of the material you're nailing, posing a risk to others. This is especially true if you are holding the material in your hand when firing the gun.
  • Blowout: The nail may go through the material and ricochet off a hard piece of metal or other material underneath.
  • Missing the work target: Take careful aim and don't rush.
  • Modified safety mechanism: Never modify a nail gun to circumvent the safety features such as removing the spring in the safety contact tip. (Source: OSHA)

The most common nail gun injuries occur as a result of unintentional double-fire, blowout, and misses.

Real World Accident

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.

2. More than half the injuries while operating nail guns is to the _____.

a. forearm and wrist
b. neck and head
c. hand and fingers
d. leg and toes

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Updated 5/28/2021

Nail Gun Triggers

trigger
Nail gun safety starts with understanding the various trigger mechanisms.

Nail gun safety starts with understanding the various trigger mechanisms. Let’s take a look at what you need to know.

How Triggers Differ

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:

  1. the order in which the controls are activated, and
  2. whether the trigger can be held in the squeezed position to discharge multiple nails OR if it must be released and then squeezed again for each individual nail.

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:

  1. Contact Firing,
  2. Full Sequential,
  3. Single Sequential, and
  4. Single Actuation,

Each trigger type is described in the next few tabs. We also provide a brief description of how the controls are activated.

3. What two types of controls do nailers rely on?

a. Finger triggers and contact safety tips
b. Engineering controls and personal protective equipment
c. Triggers and guards
d. GFCIs and safety switches

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Updated 5/28/2021

Contact Firing Trigger

contact
Contact safety tip
contact
Bump firing or bounce nailing.

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.

  • Single nail: Push the safety contact, then squeeze the trigger, or squeeze the trigger, then push the safety contact.
  • Multiple nails: Squeeze and hold the trigger, then push the safety contact to fire one nail, move and push the safety contact again to fire additional nails.

4. Which type of trigger is used when bump firing or bounce nailing?

a. Single action trigger
b. Single sequential trigger
c. Full sequential trigger
d. Contact firing trigger

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Updated 5/28/2021

Full Sequential Trigger

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.

  • Single Nail: Push the safety contact and then squeeze the trigger.
  • Multiple Nails: Release both the safety contact and trigger and repeat the process.

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.

5. Which type of trigger is always the safest trigger mechanism for the job?

a. Contact firing trigger
b. Full sequential trigger
c. Single actuation trigger
d. Single Sequential trigger

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Updated 5/28/2021

Single Sequential Trigger

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

  • Single nail: Push the safety contact, then squeeze the trigger.
  • Multiple nails: Release the trigger, move the tool, and squeeze the trigger to fire the additional nail.

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.

6. Which type of trigger can shoot multiple nails only after you release the trigger, move the tool, and squeeze the trigger again?

a. Single actuation trigger
b. Contact firing trigger
c. Single sequential trigger
d. Full sequential trigger

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Updated 5/28/2021

Single Actuation Trigger

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.

  • Single nail: Push the safety contact and squeeze the trigger, or squeeze the trigger and then push the safety contact to fire.
  • Multiple nails: Release the trigger, move tool, and squeeze the trigger to fire additional nail.

7. Like the contact firing trigger, which trigger will fire a single nail when the safety contact and trigger are activated in any order?

a. Full sequential trigger
b. Single sequential trigger
c. Full actuation trigger
d. Single actuation trigger

Check your Work

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.

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Updated 5/28/2021
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