Can Dry Type Transformers Be Used Outdoors? | CHBEB 2025 Installation & Protection Guide

Introduction

A lot of project engineers and procurement managers want to know if dry-type transformers may be utilized outside.

Yes, but only if the conditions are correct. People like dry-type transformers because they are safe, good for the environment, and easy to take care of. However, they need air to cool and insulate them. This makes them more vulnerable to weather, humidity, and dust, especially while they are outside.

This article gives an unbiased, engineering-based look at how dry-type transformers can be used safely outside, what safety criteria they need to meet, and how to pick the right manufacturer for your project.

1. What Is a Dry-Type Transformer?

Instead of oil, a dry-type transformer employs air or solid insulation, like cast resin epoxy or the VPI process. They are great for:

• Schools, hospitals, and businesses
• Substations that are underground or in a building
• Solar, wind, and hydro power are all examples of renewable energy systems.

The same “dry” design that makes it safer inside also means that you need to protect it properly outside to make sure it works and lasts.

2. Outdoor Use Depends on Enclosure Protection (IP Rating)

Whether a dry-type transformer can be used outdoors depends primarily on its enclosure rating — measured by the IP (Ingress Protection) code¹, which defines the transformer’s resistance to dust and moisture.

IP Rating	Environment	Protection Level
IP20–IP23	Indoor use	Protection against solid objects and limited moisture
IP44–IP45	Semi-outdoor	Splash-resistant, suitable for covered or ventilated areas
IP54–IP55	Outdoor	Dust-tight and rainproof, suitable for open-air installation

Recommendation: Choose enclosures with an IP45 rating or greater for outside use. For very harsh climates, IP55 is best.

3. Key Design Requirements for Outdoor Operation

• Weatherproof case: Stainless steel or powder-coated case that won’t rust, become dusty, or get UV rays.
• Ventilation system: either natural or forced-air cooling to keep things from being too hot.
• Humidity control: Put space heaters or dehumidifiers inside the cabinet to keep condensation from forming.
• A good foundation is an elevated concrete plinth with drainage to keep water from pooling.
• Check the air filters, insulation resistance, and grounding every so often.

These steps safeguard the windings and core from stress from the outside world, which makes the transformer last longer.

4. Typical Outdoor Applications

Outdoor-rated dry-type transformers are becoming increasingly common in areas where oil-filled Outdoor-rated dry-type transformers are becoming more common in places where oil-filled units are not allowed for reasons of safety or environmental protection.Some of these places are:

• Solar farms and wind substations, which are examples of renewable energy plants
• Substations and transformers erected on pads in cities
• Public infrastructure such as metro systems and tunnels
• Industrial areas with tight fire safety regulations

Their oil-free and fire-resistant design makes them safe against fire and oil hazards, allowing their use in hazardous or environmentally sensitive locations.

5. International Standards and Compliance

• IEC 60076-11² — Sets up environmental classes (E2, C2, F1) for how things behave in different levels of wetness, climate, and fire.
• IEEE C57.12.01—General requirements for dry-type power and distribution transformers.
• ANSI/NEMA 250: Standards for protecting electrical enclosures (Type/IP equivalency).

Following these rules makes it possible for the system to work reliably even in tough outside situations.

6. Advantages of Outdoor Dry-Type Transformers

Feature	Advantage
Fire safety	No flammable oil; suitable for public spaces
Eco-friendly	No oil leaks or contamination risk
Compact design	Easier to install in urban or confined areas
Low maintenance	No need for oil sampling or refilling
Customizable protection	Available with IP45–IP55 enclosures for different environments

7. Limitations to Consider

• Costs more upfront than oil-immersed varieties
• Lower range of power capacity, usually less than 10 MVA
• Managing heat in sealed enclosures is more complicated.

Oil-immersed transformers may be more cost-effective for large-scale transmission or high industrial loads.

8. Choosing the Right Supplier — Balancing Quality, Cost, and Delivery

Choosing a transformer isn’t just about its technical specifications; it’s also about finding the right balance between quality, price, and delivery time.

People around the world recognize that China’s top 10 transformer manufacturers produce well-engineered, durable products with long service life. However, their products are often more expensive and mainly focused on large-scale utility projects.

In contrast, medium-sized transformer factories can offer OEM/ODM customization, competitive pricing, and faster production cycles, making them an excellent choice for EPC contractors, distributors, and regional utilities seeking cost-effective solutions.

When selecting a supplier, always check their certifications (ISO, IEC, CE), testing capabilities (routine, type, and special tests), and material standards (copper conductors, silicon steel, insulation grade). A well-audited manufacturer that follows IEC/IEEE design standards can deliver transformers that perform as reliably as top brands — but at a more efficient cost.

CHBEB — Reliable Partner for Distribution Transformers

With over 60 years of transformer manufacturing expertise, CHBEB has become one of China’s most trusted distribution transformer suppliers. The company operates two factories in Wenzhou, one in Nanjing, and an office in Beijing, ensuring both strong production capacity and responsive customer support.

What makes CHBEB stand out:

• Strict Quality Commitment: All raw materials are 100% new and high-grade — no recycled or downgraded components.
• Proven Reliability: A qualified supplier for the State Grid Corporation of China, with a spotless record of zero major accidents.
• 100% Product Testing: Every unit is fully tested before delivery to guarantee safety, efficiency, and long service life.
• Fast-Track Orders: Ability to fulfill urgent orders in as little as one week, helping customers meet tight project deadlines.
• Custom Inventory Planning: Flexible stocking and supply strategies designed to align with customer procurement schedules.
• Global Outlook: Rooted in China and expanding worldwide, CHBEB actively supports local agents and partners, including assistance with market-specific certifications.
• Flexible Customization: Tailored transformer designs for utilities, contractors, and industrial clients, with reliable quality and fast delivery.

👉 Looking for a distribution transformer manufacturer that combines Chinese manufacturing strength with international standards?Contact CHBEB for a tailored solution or Download our full transformer catalog here.

Conclusion

Yes — dry-type transformers can be safely used outdoors, provided they are properly protected with IP-rated enclosures, well ventilated, and designed in compliance with IEC/IEEE international standards. Their fire safety, low maintenance, and eco-friendly operation make them ideal for modern infrastructure, renewable energy, and public utility projects.

When purchasing, remember that “best” doesn’t always mean “most expensive.” While high-end brands deliver proven reliability, medium-sized, IEC-certified manufacturers often provide faster delivery, flexible customization, and a lower total project cost — without compromising on technical quality.

Ultimately, the right transformer is the one that matches your project’s environment, voltage class, safety requirements, and budget — ensuring stable, efficient, and long-term performance for years to come.

1. Ingress Protection (IP) Code ↩︎
2. IEC 60076-11: Power Transformers – Dry-type Transformers ↩︎