Single Phase Pad Mounted Transformer (URD Series)

The Single Phase Pad Mounted Transformer is the cornerstone of modern Underground Residential Distribution (URD). Designed to be installed at ground level on a concrete or fiberglass pad, this "Mini-Substation" eliminates the need for unsightly overhead poles and wires. It serves as the final step-down point, converting medium voltage (e.g., 12.47kV or 24.9kV) to 120/240V for households and small commercial sites.

As a comprehensive single phase underground transformer solution, our series is engineered for universal utility acceptance. Every unit in this catalog is manufactured in strict accordance with ansi c57 12.25. This specific standard governs the dimensional integrity, bushing heights, and safety clearances for single-phase units, ensuring our transformers are mechanically interchangeable with existing utility infrastructure across North American grids.

Select your required capacity below to understand the specific engineering application.

1. The Residential Compact Series (25 - 50 kVA)

Ideal for: Cul-de-sacs, small clusters of homes, and street lighting.

25 kVA: The industry's volume leader. A 25 kva pad mounted transformer is typically sized to power 4 to 6 average energy-efficient homes. Its low profile (often <24 inches tall) allows it to hide discreetly behind landscaping bushes. For retrofit projects requiring a compact footprint, the 25 kva pad mount transformer remains the standard specification.

50 kVA: As average household consumption rises with larger HVAC systems, the 50 kva pad mounted transformer is becoming the new standard for new housing developments. It provides the necessary thermal headroom to handle simultaneous peak loads across 8-10 homes without overheating the mineral oil.

Green 25 kVA pad mounted transformer installed discreetly in a

residential front yard.

2. The High-Density Estate Series (75 - 100 kVA)

Ideal for: Large luxury estates, multi-family compounds, and EV-ready neighborhoods.

75 kVA: This unit bridges the gap between standard residential and light commercial. A 75 kva pad mount transformer is frequently specified for large luxury villas or small apartment blocks where the load density exceeds the capability of smaller cans.

100 kVA: With the proliferation of Level 2 Electric Vehicle chargers, residential load profiles are changing. The 100 kva pad mount transformer offers the robust capacity needed for modern "Electrified Neighborhoods," preventing voltage flicker when multiple EVs plug in simultaneously at night.

3. The Commercial Heavyweight Series (150 - 167 kVA)

Ideal for: Light commercial strips, schools, and large service entrances.

150 kVA / 167 kVA: While the IEEE standard technically defines capacities up to 250 kVA, we focus on the most practical utility ratings. We offer the globally common 👉 150 kva pad mount transformer for general commercial applications. Additionally, for strict ANSI markets, we supply the 167 kva pad mount transformer, which represents practically the "Workhorse Limit" for most utility inventories (exactly 1/3 of a 500 kVA bank). These units are the go-to solution for delivering massive single-phase power to schools, churches, or small strip malls via underground feeds.

Regardless of capacity, all our single phase pad mounted distribution transformers share a unified, utility-grade architectural standard focusing on public safety and grid flexibility.

 

1. Dead-Front & Tamper-Proof Design

Public safety is paramount. Our cabinets feature a "Dead-Front" construction, meaning there are no exposed live parts in the high-voltage compartment.

Tamper Resistance: The cabinet is locked with a specialized Penta-head bolt (requiring a 5-sided socket) and padlock hasp. The HV compartment cannot be opened unless the LV compartment is opened first, ensuring a distinct access sequence that prevents unauthorized entry by children or vandals.

Open compartment of single phase pad transformer showing

dead-front insulated connections.

2. Loop Feed Circuitry

Unlike overhead units which are dead-end, these units act as nodes in a ring.

HV Bushings: Equipped with 200A Bushing Wells (typically 2 in, 2 out) to facilitate a "Loop Feed" configuration. If a cable fault occurs in one section of the neighborhood, utility crews can isolate the bad section and feed the transformer from the other direction, minimizing outage duration.

3. Integrated Protection (Bay-O-Net)

To protect the grid, each unit houses internal Bay-O-Net Fuses immersed in the oil. These are field-replaceable and work in series with a partial-range Current Limiting Fuse (CLF) to clear both secondary overloads and high-current primary faults, preventing tank rupture.

Proper installation requires a pre-cast or poured concrete base. We provide the specific dimensions for the single phase transformer pad to ensure the cable window aligns perfectly with your underground conduits.