Hard hats are a crucial piece of personal protective equipment for workers in construction, manufacturing, mining, and other industrial occupations. The hard hat is designed to protect the wearer’s head from impact, penetration, electrical shock, and other workplace hazards.
In the United States, the key standards organization for hard hats is the American National Standards Institute (ANSI). ANSI has established performance and testing standards for hard hats under the ANSI Z89.1 standard. This helps ensure hard hats on the market can provide adequate protection for workers.
The ANSI Z89.1 standard divides hard hats into three classes based on the levels of impact and electrical protection they provide:
Class G – General
Class G hard hats are general purpose hard hats that provide impact and penetration protection but limited voltage protection. They are intended for protection from blows to the head caused by falling objects. Class G hard hats have a full brim and provide impact protection from forces caused by objects striking the top or sides of the hat.
The specifics of impact testing for Class G hard hats include:
| Impact Test | Criteria |
| Top impact – 2.5 kg weight dropped from 304 cm | Maximum force transmitted to headform must be less than 5000 g |
| Side impact – 2.5 kg weight dropped from 152 cm | Maximum force transmitted to headform must be less than 5000 g |
Class G hard hats are tested by dropping weighted objects onto samples from different heights. The maximum allowable force transmitted to the headform on which the hat is mounted is 5000 g or less for the hat to pass testing.
In terms of penetration protection, Class G hard hats must resist a 3.18 kg pointed spike dropped from a height of 1 m onto the shell. When tested, the spike must not contact the headform.
For electrical protection, Class G hard hats provide limited voltage protection, tested to 2200 volts or less. This protects against bumps to live electrical conductors at lower voltages but does not substitute for voltage-rated rubber insulating equipment.
Class E – Electrical
Class E hard hats provide dielectric electrical protection beyond that offered by Class G hats. They are intended for protection against falling objects plus high voltage electrical hazards.
Class E hard hats must pass the same tests for impact protection as Class G hats. In addition, they require further electrical testing consisting of:
| Electrical Test | Criteria |
| Voltage test | Withstand 20,000 volts AC for 3 minutes with no current flow to headform |
| Proof test | Withstand 120 volts AC for 3 minutes with leakage current less than 3 mA to headform |
| Flame test | Resist ignition when exposed to methane gas flame for 5 seconds |
The 20,000 volt AC proof test simulates exposure to high voltage electrical hazards. The hard hat must prevent any current flow to the headform during testing. The 120 volt test ensures some minimal electrical leakage protection at standard voltages.
The flame test ensures the hard hat material will not continue to burn after very brief exposure to an open flame, which could otherwise ignite flammable vapors.
Class E hard hats provide crucial protection for electrical trades workers, linemen, and others exposed to high voltage situations. However, they do not replace electrical safety gloves and other rubber insulating PPE for close work on live conductors.
Class C – Conductive
Class C hard hats provide lightweight impact protection for workers in confined spaces. They are also known as bump caps.
Class C hard hats are designed differently than Class G and E hats. They have reduced brim coverage and do not fully enclose the head. This allows improved mobility and visibility in tight spaces where a full brim hard hat would prove restrictive.
Instead of impact testing, Class C hard hats require a label clearly indicating the limited Impact protection and electrical shock protection they provide.
Class C hard hats may also include ventilation holes not permitted in Class G and E to improve airflow. Due to the reduced coverage, Class C hats only provide protection from bumps to the top of the head, not the sides. They are unsuitable for protecting against falling objects or electrical hazards.
Example occupations where Class C hard hats are used include:
– Construction laborers in confined spaces
– Miners in low coal mines
– Assembly line workers in cramped machinery spaces
Class C hard hats should only be used where allowed by a workplace hazard analysis. Otherwise, Class G or E hard hats are preferable for impact and electrical protection. Proper hard hat selection and fit are important in ensuring the intended level of protection.
Identifying Hard Hat Classes
All hard hats conforming to ANSI Z89.1 requirements must be marked with the specific class – G, E, or C. This allows easy identification of the protection level provided. Additional date, model, and manufacturer markings are also required.
It is crucial for employers to select the proper class of hard hat for the hazards present in the workplace. Equally important is proper education of workers on the meaning behind hard hat markings and selection of appropriate protective headgear.
Proper use and maintenance of hard hats is also essential. Workers should inspect hard hats regularly for cracks, dents, or signs of aging that can compromise protection. Head protection should be replaced after any significant impact or electrical exposure per the manufacturer’s recommendations.
Conclusion
The ANSI Z89.1 standard provides crucial specifications that allow hard hats to effectively protect workers from common industrial hazards. The three classes – G, E, and C cover general, electrical, and conductive hard hat applications. Class G hard hats provide basic impact protection. Class E hats add dielectric electrical protection. Class C lightweight bump caps trade coverage for mobility in confined spaces. Proper class selection, use, and maintenance helps ensure hard hats perform their vital protective role. Hard hats have saved countless lives and prevented serious injuries over the decades since becoming standard equipment across general industry, construction, utilities and other hazardous vocations where head protection is essential.
