new used transformersESU buys, sells and stocks Electrical Supplies for Electricians. Power Transformers, Circuit Breakers, Fuses, Panelboards and much more. For transformers, ESU, Inc. has a large inventory of new and used buck boost and auto transformers  If you require I phase 3 Phase 208/240, 208 to 240, 208 to 480, 120 to 240 or other voltages we usually have the transformer in stock.

We usually stock Acme, Westinghouse, Cutler Hammer, ITE Siemens, FPE  Federal Pacific, Square D, General Electric and Zinsco products.

We also carry a wide variety of commercial power transformers. Low Voltage Distribution General Purpose Commercial Transformers for all of San Diego. ESU offers a wide selection of electrical products that include buck-boost transformers, low voltage lighting transformers, mini power centers, and autotransformers.

For four decades, Electrical Supplies Unlimited has been the go-to source for electrical supplies in San Diego, proudly serving electricians and electrical companies with top-notch products and unparalleled expertise. With a rich legacy of 30 years in the industry, we have established ourselves as a trusted supplier, stocking a comprehensive range of new and used power transformers, circuit breakers, panel boards, and various other electrical essentials. Our commitment to excellence is evident in our diverse inventory and our dedication to meeting the unique needs of electricians across San Diego. Whether you're working on a residential project or a large-scale commercial venture, Electrical Supplies Unlimited is here to provide the quality products and personalized service that have been our hallmark for over three decades.

Electrical Supplies Unlimited stands as a beacon of reliability for electricians and electrical companies in San Diego, offering a vast selection of electrical supplies for over 30 years. As a seasoned supplier, we take pride in our extensive stock of new and used power transformers, circuit breakers, panel boards, and more, catering to the diverse needs of electricians across the region. Our commitment to providing high-quality products is matched only by our dedication to exceptional customer service. At Electrical Supplies Unlimited, we understand the unique requirements of electricians and electrical projects, and our experienced team is ready to assist you in finding the right solutions. Trust us as your partner in electrical supplies, where decades of expertise meet a commitment to quality that has stood the test of time.

All our recycled equipment has been tested and has our guarantee.

An electrical transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This effect is called mutual induction


A single phase transformer is a type of transformer which operates on single-phase power. 

Single-phase transformers are usually used for single special applications or voltages. For instance, equipment that specifically requires 240 volts single-phase where the service voltage is 120/208 volts. For an application like this, it is common to only provide a single-phase transformer for the equipment because there won’t be a different electrical loads served by it. 

Phase imbalances can occur when a single-phase transformer is used for general distribution while using a three-phase utility. If a property is served by single-phase and a transformer is used (e.g., for isolation) then a single-phase transformer would be appropriate.

Three-phase transformers are a type of transformers that are used to change voltages of electrical systems with three phases. There are different types of configurations for three phase transformers: star-star, delta-delta, star-delta, and delta-star. 

Core-type transformers act as a single-core, three-phase transformers where each phase is magnetically coupled to each other.