What Are The Different Safety Classes Under The En Iso 20345 Standard? A Guide To S1, S2, S3, S4, S5

To put it simply, the EN ISO 20345 standard classifies safety footwear into escalating levels of protection, starting with basic toe protection and adding features like puncture resistance, water resistance, and slip resistance. The main classes are S1, S1P, S2, S3, S4, and S5, each designed to counter specific workplace hazards.

The core principle isn't about finding the "best" safety class, but about correctly matching the specific protective features of the footwear to the known risks of your work environment. Choosing the right class is a fundamental step in risk assessment.

What are the different safety classes under the EN ISO 20345 standard? A Guide to S1, S2, S3, S4, S5

The Foundation of All Safety Footwear

The 200-Joule Mandate

Every shoe or boot certified under EN ISO 20345 must first meet the SB (Safety Basic) standard. This is not a class you typically select but the absolute minimum requirement for all others.

The non-negotiable feature of an SB-rated shoe is a toe cap capable of withstanding a 200-joule impact. This ensures protection against heavy falling objects, forming the bedrock upon which all higher S-classes are built.

Decoding the Primary Safety Classes (S1-S5)

The classification system is progressive. Each higher number incorporates the features of the classes below it, with the exception of the S4/S5 categories, which are distinct.

S1: The Standard for Dry, Indoor Environments

An S1 shoe includes the basic SB toe cap plus antistatic properties, an oil-resistant outsole, and energy absorption in the heel region. This class is ideal for indoor work where there is no risk of water or sharp objects underfoot.

S1P: Adding Puncture Protection

The S1P class includes all the features of S1 but adds a penetration-resistant midsole. This is a critical upgrade for environments where stepping on nails, screws, or other sharp debris is a real risk, such as in carpentry or demolition.

S2: Introducing Water Resistance

An S2 shoe contains all the protective elements of the S1 class but adds a water-resistant upper. This makes it suitable for working in damp conditions or outdoors where light rain is expected.

S3: The Comprehensive All-Rounder

The S3 classification is one of the most common and versatile. It combines all the features of an S2 shoe (including water resistance) with the penetration-resistant midsole of the S1P class. This makes it the go-to standard for general construction and most outdoor trades.

S4 & S5: The Waterproof Specialists

The S4 and S5 classes are different. They are typically boots made entirely from a moulded polymer or rubber, making them 100% waterproof, not just water-resistant.

S4 boots have the basic SB toe cap, antistatic properties, and are fully waterproof.
S5 is the highest level of protection, including all S4 features plus a penetration-resistant midsole. These are essential for work in extremely wet, muddy, or flooded conditions.

Understanding Additional Markings and Protections

Beyond the main S-class, additional codes specify protection against specialized hazards.

Slip Resistance (SRC)

Footwear is tested for slip resistance on two different surfaces. SRC is the highest rating, indicating the shoe has passed both tests:

SRA: Tested on ceramic tile wetted with a soap solution.
SRB: Tested on smooth steel with glycerol.

Thermal and Environmental Protection

Specific codes denote resistance to temperature extremes:

HI: Heat insulation for the sole.
CI: Cold insulation for the sole.
HRO: Heat-resistant outsole, able to withstand contact with a 300°C surface for one minute.

Specialized Hazard Resistance

Other important markings include:

ESD: Electrostatic Dissipative, for protecting sensitive electronic components.
CR: Cut-resistant upper, providing protection against sharp objects like glass or sheet metal.

Key Trade-offs in Footwear Selection

Choosing the right footwear involves balancing protection with other practical factors.

Protection vs. Comfort

Higher levels of protection, like those found in S3 or S5 boots, often result in a heavier and more rigid shoe. For all-day wear in a low-risk environment, a lighter S1 shoe may provide significantly more comfort and reduce fatigue.

Water Resistance vs. Breathability

While an S2 or S3 shoe's water-resistant upper is great for damp conditions, it is less breathable than a standard S1 shoe. Similarly, fully waterproof S4/S5 boots trap sweat, which can be a consideration in warm climates or during strenuous work.

Making the Right Choice for Your Environment

Your selection should be a direct response to your daily tasks and potential risks.

If your primary focus is dry, indoor work (e.g., logistics, assembly): An S1 shoe provides the necessary impact and antistatic protection without unnecessary weight. Choose S1P if sharp floor debris is a risk.
If your primary focus is general construction or outdoor trades: An S3 boot offers the most complete and versatile protection against impact, water, and puncture hazards.
If your primary focus is work in extremely wet or hazardous liquid environments: An S4 boot is the waterproof standard, but upgrading to an S5 is critical if puncture risks are present.

By understanding these codes, you can move beyond simply meeting a requirement and choose footwear that is precisely tailored to keep you safe and productive.

Summary Table:

Safety Class	Key Protective Features	Ideal For
S1	Basic toe cap (200J), antistatic, oil-resistant sole	Dry, indoor environments (e.g., warehousing, assembly)
S1P	All S1 features + Penetration-resistant midsole	Indoor work with puncture risks (e.g., carpentry, demolition)
S2	All S1 features + Water-resistant upper	Damp conditions, light outdoor work
S3	All S2 features + Penetration-resistant midsole	General construction, most outdoor trades
S4	Basic toe cap, fully waterproof (moulded boot)	Extremely wet environments
S5	All S4 features + Penetration-resistant midsole	Wet environments with puncture risks (e.g., utilities, mining)

Ensure Your Workforce Has the Right Protection

Choosing the correct safety class is critical for compliance and worker safety. As a large-scale manufacturer, 3515 produces a comprehensive range of EN ISO 20345 certified footwear for distributors, brand owners, and bulk clients. Our production capabilities encompass all types of safety shoes and boots, from lightweight S1 models to heavy-duty S5 waterproof boots.

We can help you select or manufacture the perfect safety footwear tailored to your specific hazards and comfort requirements.

Contact us today to discuss your needs and request a catalog!

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