Light Pole Transformer: Detailed Analysis of Standards, Grades, and Industry Applications

Types of Light Pole Transformers

A light pole transformer is a crucial electrical component mounted on or near lighting poles that ensures safe and efficient power delivery to outdoor lighting systems. These transformers adapt high-voltage utility power to levels suitable for various lighting technologies, enhancing safety, reliability, and performance across residential, commercial, and municipal applications.

With the evolution of lighting technology—especially the widespread adoption of LED systems—transformers have become more specialized. Below is a comprehensive overview of the most common types of light pole transformers, their functions, advantages, and ideal use cases.

Step-Down Transformers

Designed to reduce high incoming voltage (e.g., from 120V/277V or higher) to safer levels (e.g., 12V or 24V) suitable for lighting fixtures.

Advantages

• Enhances safety by lowering voltage at point of use
• Ideal for powering multiple fixtures simultaneously
• Widely compatible with standard lighting systems
• Supports energy-efficient operation

Limitations

• Requires proper grounding and insulation
• May generate heat under continuous load
• Larger models need protective enclosures

Best for: Streetlights, parking lots, parks, and large-scale outdoor lighting networks

Step-Up Transformers

Increase voltage levels to minimize power loss during long-distance transmission before stepping down again near the load.

Advantages

• Reduces current and line losses over extended runs
• Improves transmission efficiency
• Useful in remote or rural lighting installations

Limitations

• Rarely used directly at light poles
• Higher risk if not properly insulated
• More complex installation and safety protocols

Best for: Remote area lighting, long-span roadway systems, temporary high-voltage distribution setups

Isolation Transformers

Provide galvanic isolation between the primary power source and secondary lighting circuit, preventing direct electrical contact.

Advantages

• Significantly improves electrical safety
• Reduces risk of electric shock and ground faults
• Protects sensitive equipment from surges and noise
• Meets strict code requirements for wet locations

Limitations

• Slightly less energy efficient due to magnetic losses
• Typically larger and heavier than non-isolated units
• Higher initial cost

Best for: Outdoor pedestrian areas, public plazas, coastal regions, and damp environments

Multi-Tap Transformers

Feature multiple output terminals allowing selection of different voltage levels (e.g., 12V, 16V, 20V, 24V) to suit various lighting loads.

Advantages

• Highly flexible for mixed lighting setups
• Compensates for voltage drop over distance
• Reduces need for multiple transformer types
• Easy to adjust during installation or upgrades

Limitations

• Potential for incorrect tap selection
• Requires technical knowledge for optimal setup
• Slightly more complex wiring

Best for: Landscape lighting, decorative lighting arrays, multi-zone outdoor lighting systems

LED Drivers

Specialized transformers (often constant-current or constant-voltage power supplies) designed specifically for LED lighting systems.

Advantages

• Optimized for LED efficiency and longevity
• Provides stable current/voltage output
• Supports dimming and smart control integration
• Compact and energy-efficient designs available

Limitations

• Sensitive to overheating in enclosed spaces
• Lower-quality drivers may fail prematurely
• Compatibility issues with certain dimmers or controls

Best for: Modern streetlights, architectural lighting, smart city infrastructure, energy-saving retrofits

Encapsulated Transformers

Sealed units potted in resin or oil to protect internal components from moisture, dust, vibration, and corrosion.

Advantages

• Extremely durable in harsh environments
• Resistant to water, chemicals, and temperature extremes
• Low maintenance and long service life
• Reduced risk of internal arcing or short circuits

Limitations

• Difficult or impossible to repair if damaged
• Higher upfront cost
• Heavier than non-encapsulated versions

Best for: Coastal installations, industrial zones, cold climates, and high-humidity areas

Type	Voltage Function	Safety Level	Durability	Ideal Application
Step-Down	Reduces voltage	High	Good	Street lighting, parking lots
Step-Up	Increases voltage	Moderate	Fair	Long-distance transmission
Isolation	Same or stepped voltage with isolation	Very High	Good	Wet/damp public areas
Multi-Tap	Adjustable output	High	Good	Landscape & decorative lighting
LED Drivers	Constant current/voltage	High	Varies by quality	LED streetlights, smart lighting
Encapsulated	Any type (protected)	Very High	Excellent	Hazardous or extreme environments

Expert Tip: When selecting a light pole transformer, always consider local electrical codes, environmental conditions, and future expansion needs. For LED retrofits, ensure compatibility between the driver and control systems (e.g., dusk-to-dawn sensors or dimming protocols) to maximize energy savings and system lifespan.

Function and Features of Light Pole Transformers

Light pole transformers are essential components in modern street lighting systems, enabling safe and efficient power delivery to public lighting infrastructure. Mounted either on or near light poles, these compact electrical devices play a crucial role in transforming high-voltage electricity from distribution lines into lower, usable voltages for streetlights. Understanding their core functions and key features helps ensure reliable operation, improved safety, and long-term cost savings in urban and rural lighting networks.

Core Functions of Light Pole Transformers

Voltage Reduction

As step-down transformers, light pole units convert high-voltage electricity (typically 7,200V or higher) from primary distribution lines to lower voltages (usually 120V or 240V) suitable for street lighting fixtures. This voltage transformation is critical for ensuring compatibility with standard lighting systems and preventing damage due to overvoltage.

By delivering properly regulated voltage, these transformers enhance operational safety, reduce fire hazards, and extend the lifespan of bulbs and LED drivers used in modern luminaires.

Electrical Isolation

One of the most important safety functions of a light pole transformer is providing galvanic isolation between the high-voltage primary circuit and the low-voltage secondary (lighting) circuit. This separation prevents dangerous voltages from reaching accessible parts of the lighting system.

Isolation also protects against voltage surges caused by lightning strikes, grid fluctuations, or equipment faults, significantly improving system resilience and reducing maintenance costs.

Stable Current Supply

Light pole transformers are engineered to deliver consistent and stable current flow tailored to the specific electrical demands of the connected lighting load. Whether powering a single fixture or multiple lights in a series, they maintain optimal current levels to prevent flickering, dimming, or premature lamp failure.

This regulation ensures uniform illumination across roadways and walkways, contributing to better visibility and enhanced public safety at night.

Phase Transformation

These transformers can operate within both single-phase and three-phase power distribution systems. In residential or suburban areas, single-phase models are commonly used, while three-phase transformers serve larger installations like highways, commercial districts, or industrial zones.

Their ability to interface with various grid configurations makes them highly versatile and adaptable to different municipal power infrastructures, supporting scalable and efficient lighting deployment.

Key Design and Operational Features

Tap Changing Capability

Many advanced light pole transformers come equipped with either on-load or off-load tap changers, allowing technicians to adjust output voltage in response to changing line conditions or seasonal load variations.

This feature ensures consistent performance despite fluctuations in input voltage or increased demand during peak hours, maintaining optimal lighting levels and protecting connected equipment from stress.

Compact and Space-Efficient Design

Designed for integration into tight urban spaces, light pole transformers are built with a compact footprint. They are often pole-mounted or pad-mounted at the base, minimizing land use and visual impact.

Their streamlined design allows seamless incorporation into sidewalks, medians, and narrow streets without obstructing traffic or pedestrian movement, making them ideal for dense urban environments.

Robust Durability

Built to endure harsh outdoor conditions, these transformers are constructed using corrosion-resistant materials such as weatherproof steel enclosures and sealed bushings. They can withstand extreme temperatures, moisture, salt spray, dust, and pollution—common challenges in coastal, industrial, and high-humidity regions.

This rugged construction ensures long service life and minimal downtime, even in demanding climates, reducing the need for frequent replacements or repairs.

Energy Efficiency (Low Losses)

Modern light pole transformers utilize advanced core materials (e.g., amorphous metal or high-grade silicon steel) and precision-wound coils to minimize core and copper losses. These energy-efficient designs reduce wasted heat and improve overall system efficiency.

Lower energy losses translate into reduced operational costs and a smaller carbon footprint—key considerations for municipalities aiming to meet sustainability goals and reduce electricity expenditures over time.

Overload and Short-Circuit Protection

Integrated protective mechanisms such as fuses, circuit breakers, or reclosers safeguard the transformer and lighting circuit from overloads, short circuits, and fault currents. These devices automatically disconnect power during abnormal conditions to prevent equipment damage and potential fire hazards.

Such built-in protection enhances system reliability, reduces maintenance frequency, and improves safety for both maintenance personnel and the general public.

Feature	Function	Benefits
Voltage Reduction	Converts high voltage to safe, usable levels	Equipment protection, safety, compatibility with lighting systems
Electrical Isolation	Separates primary and secondary circuits	Prevents shock hazards, surge protection, system stability
Tap Changing	Adjusts output voltage as needed	Maintains performance under variable loads, prolongs equipment life
Compact Design	Space-saving physical configuration	Ease of installation, suitability for urban settings
Durability	Resists environmental stressors	Long lifespan, low maintenance, reliable operation
Low Energy Losses	Minimizes wasted power	Cost savings, energy conservation, environmental benefits

Important: Regular inspection and maintenance of light pole transformers are essential to ensure continued safe and efficient operation. Issues such as oil leakage (in liquid-filled units), insulation degradation, or damaged enclosures should be addressed promptly by qualified personnel. Always follow local electrical codes and manufacturer guidelines when installing or servicing these units to avoid hazards and maintain compliance.

Scenarios of Light Pole Transformers

Light pole transformers play a vital role in modern outdoor lighting systems by stepping down high-voltage power from utility lines to safe, usable levels for lighting fixtures. These compact yet powerful devices are strategically integrated into light poles across various environments to ensure reliable, efficient, and safe illumination. Below are the most common applications where light pole transformers are essential.

Stadiums and Sports Facilities

Stadiums and sports complexes require high-intensity lighting to support nighttime events, training sessions, and spectator safety. Light pole transformers are critical in these settings, converting medium-voltage supply (typically 4.8 kV to 13.8 kV) to lower voltages (120V–480V) needed by powerful lighting systems such as metal halide, high-pressure sodium (HPS), or modern LED floodlights.

• Multiple tall light poles with integrated transformers provide uniform illumination across large playing fields
• Transformers are often pole-mounted or pad-mounted nearby for easy maintenance and cooling
• Used in conjunction with photocells and timers to automate lighting schedules
• Essential for meeting broadcast lighting standards in professional sports venues

Safety note: Proper grounding and weatherproof enclosures are crucial due to exposure to outdoor elements and potential vandalism.

Parking Lots

Parking lots—whether at shopping centers, office buildings, or residential complexes—rely on consistent lighting for security, visibility, and compliance with municipal codes. Light pole transformers power a variety of lighting technologies, including energy-efficient LED fixtures and traditional HPS lamps, ensuring a steady voltage supply despite fluctuations in the primary distribution network.

• Transformers can be mounted atop the pole (integral design) or housed underground in vaults
• Enable zoning of lighting circuits for targeted illumination and energy savings
• Support smart lighting systems with motion sensors and remote monitoring capabilities
• Reduce voltage drop over long pole runs, maintaining brightness at the farthest fixtures

Pro tip: Modern LED retrofits often allow for reduced transformer capacity, offering cost and energy savings during upgrades.

Public Parks and Recreation Centers

To promote public safety and extend usable hours, parks and recreation areas are equipped with outdoor lighting powered by light pole transformers. These transformers ensure that pathways, playgrounds, sports courts, and picnic areas remain well-lit after sunset, supporting community engagement and deterring criminal activity.

• Transformers adapt to mixed lighting loads, from low-wattage path lights to high-output area floodlights
• Often paired with solar-assist systems or battery backups in remote park locations
• Designed to minimize electromagnetic interference with nearby residential areas
• Constructed with tamper-resistant enclosures to prevent unauthorized access

Environmental consideration: Many parks now use dark-sky compliant fixtures and shielded transformers to reduce light pollution and protect nocturnal wildlife.

Commercial and Industrial Areas

In commercial plazas, manufacturing facilities, warehouses, and logistics hubs, reliable outdoor lighting is essential for operational efficiency, worker safety, and security. Light pole transformers deliver stable power to large-scale lighting arrays used in loading docks, storage yards, and perimeter fencing.

• Handle heavy electrical loads from multiple high-bay or mast-arm fixtures
• Engineered for durability in harsh environments with dust, moisture, and temperature extremes
• Support emergency lighting circuits and backup generators during outages
• Facilitate compliance with OSHA and NFPA safety standards for workplace illumination

Maintenance advantage: Centralized transformer placement allows for easier diagnostics and servicing without disrupting entire site operations.

Highways and Major Roads

For highways, interchanges, tunnels, and major arterial roads, continuous and dependable lighting is a cornerstone of traffic safety. Light pole transformers are strategically placed along roadways to step down high-voltage transmission lines to levels suitable for streetlights, ensuring drivers have clear visibility at night and in adverse weather conditions.

• Typically installed every few poles or at junction boxes along the right-of-way
• Designed for high reliability and long service life with minimal maintenance
• Integrated with intelligent transportation systems (ITS) for adaptive lighting control
• Must meet strict DOT and AASHTO standards for performance and safety

Critical function: Prevents voltage fluctuations that could cause flickering or premature lamp failure, which poses risks on high-speed roadways.

Expert Insight: When planning outdoor lighting projects, always consider future expansion and technology upgrades. Specifying light pole transformers with a 20–25% capacity margin allows for adding more fixtures or transitioning to higher-efficiency systems without replacing the transformer. Additionally, opting for smart transformers with remote monitoring can significantly reduce maintenance costs and improve system reliability.

Application	Typical Voltage Input	Output Voltage	Common Lighting Types	Transformer Mounting Style
Stadiums & Sports Facilities	7.2 kV – 13.8 kV	120/208V, 277/480V	Metal Halide, LED Floodlights	Pole-top, Pad-Mounted
Parking Lots	4.8 kV – 13.8 kV	120/240V, 277V	LED, HPS, Induction	Integral, Underground Vault
Public Parks	4.8 kV – 7.6 kV	120V, 240V	LED Path Lights, Low-Pressure Sodium	Pole-Mounted, Canopy
Commercial/Industrial	7.2 kV – 13.8 kV	277/480V, 480V Delta	High-Bay LED, Metal Halide	Pad-Mounted, Pole-Top
Highways & Major Roads	12.47 kV – 34.5 kV	120V, 240V, 277V	LED Streetlights, HPS	Pole-Top, Junction Box

Additional Considerations for Light Pole Transformer Applications

• Weather Resistance: All outdoor transformers must be rated for wet locations (NEMA 3R or higher) to withstand rain, snow, and humidity
• Vandalism Protection: Tamper-resistant enclosures and lockable compartments are recommended in public areas
• Noise Levels: Amorphous metal core transformers offer quieter operation in noise-sensitive zones like parks and residential borders
• Energy Efficiency: DOE 2016-compliant transformers reduce losses and support sustainability goals
• Smart Grid Integration: Modern transformers can include sensors for voltage monitoring, fault detection, and integration with city-wide lighting management systems

How to Choose the Right Light Pole Transformer: A Comprehensive Guide

Selecting the appropriate light pole transformer is a crucial step in ensuring the reliability, efficiency, and safety of outdoor lighting systems. Whether you're managing a municipal project, commercial property, or residential installation, choosing the wrong transformer can lead to system failures, increased maintenance costs, or even safety hazards. This guide provides detailed insights into the key factors to consider when selecting a light pole transformer, helping you make an informed decision that balances performance, durability, and cost-effectiveness.

Safety Warning: Always ensure electrical installations are performed or supervised by a licensed electrician. Improper transformer selection or installation can result in electrical hazards, fire risks, or damage to connected lighting fixtures. Verify compliance with local electrical codes and standards such as NEC (National Electrical Code) and IEEE.

Key Factors to Consider When Choosing a Light Pole Transformer

1. Calculate and Match Wattage Requirements

   Wattage is the most critical specification when selecting a transformer. It determines the transformer’s capacity to power your lighting load without overheating or underperforming.

   • Sum the total wattage of all connected lighting fixtures (e.g., LED, HID, or metal halide lamps).
   • Add a 15–20% safety margin to accommodate future expansions or voltage fluctuations. For example, if your total lighting load is 800 watts, choose a transformer rated for at least 920–960 watts.
   • A transformer with insufficient wattage will overheat, trip breakers, or fail prematurely.
   • An oversized transformer operates inefficiently at low loads, increasing energy costs and reducing lifespan.

   Tip: Use the formula: Minimum Transformer Capacity = Total Fixture Wattage × 1.15

2. Verify Input and Output Voltage Compatibility

   Matching voltage specifications ensures seamless integration with your power supply and lighting system.

   • Input Voltage: Must match the available power source (e.g., 120V, 240V, 277V, or 480V). Common streetlight systems use 120V or 277V (from commercial building mains).
   • Output Voltage: Should align with the voltage requirements of your lighting fixtures (e.g., 12V, 24V for low-voltage landscape lights, or 120V for standard poles).
   • Use step-down transformers for reducing line voltage to safe levels for specific fixtures.
   • Ensure the transformer is designed for continuous duty to handle sustained loads without degradation.
3. Evaluate Built-In Safety Features

   Safety mechanisms protect both equipment and personnel from electrical faults and environmental stress.

   • Look for models with short-circuit protection to prevent damage during electrical surges.
   • Over-voltage protection safeguards against voltage spikes from the grid.
   • Over-temperature shutdown prevents overheating in enclosed or poorly ventilated spaces.
   • Thermal fuses and automatic reset circuits enhance long-term reliability.
   • Grounding terminals and tamper-resistant enclosures improve electrical safety, especially in public areas.
4. Assess Durability and Environmental Resistance

   Light pole transformers are exposed to harsh outdoor conditions, so robust construction is essential.

   • Choose units with corrosion-resistant housings (e.g., aluminum or powder-coated steel).
   • Look for NEMA 3R or NEMA 4X-rated enclosures that provide protection against rain, snow, dust, and UV exposure.
   • Ventilated designs help dissipate heat, while gasketed covers prevent moisture ingress.
   • Sealed conduit entries and waterproof wire glands ensure long-term performance in wet environments.
   • Consider transformers with thermal management features like heat sinks or passive cooling fins.
5. Ensure Ease of Installation and Maintenance

   A user-friendly design reduces labor time, lowers installation costs, and simplifies future servicing.

   • Select models that come with clear wiring diagrams and installation manuals.
   • Look for terminal blocks with labeled connections for quick and error-free setup.
   • Mounting brackets or pole straps should allow secure attachment to standard light poles (typically 2.5" to 3" diameter).
   • Accessible knockouts and generous wire bending space make field wiring easier.
   • Modular designs or DIN-rail mounting options can streamline replacements and upgrades.

Selection Criteria	Recommended Specifications	Common Mistakes to Avoid	Verification Tips
Wattage Capacity	Total load × 1.15–1.2 safety margin	Ignoring future expansion needs	Add 20% extra capacity for flexibility
Input Voltage	Match supply voltage (120V, 277V, etc.)	Assuming compatibility without checking	Confirm with multimeter or utility provider
Output Voltage	Matches fixture requirements (12V, 120V, etc.)	Mismatching low-voltage systems	Check fixture nameplate ratings
Environmental Rating	NEMA 3R or higher	Using indoor-rated units outdoors	Inspect enclosure for IP/NEMA certification
Safety Protections	Short-circuit, over-voltage, thermal protection	Choosing bare-bones models to save cost	Review product datasheet for protection features

Expert Tip: When installing multiple light poles, consider using centralized transformers with distribution panels instead of individual pole-mounted units. This approach reduces maintenance complexity and improves load balancing across circuits.

Additional Recommendations for Long-Term Performance

• Choose energy-efficient transformers with high efficiency ratings (e.g., DOE 2016 compliant or Class I efficiency).
• Opt for models with UL, CSA, or ETL certification to ensure compliance with North American safety standards.
• Label transformers clearly with voltage, wattage, and circuit information for easier troubleshooting.
• Schedule periodic inspections to check for corrosion, loose connections, or overheating signs.
• Keep spare transformers on hand for critical infrastructure to minimize downtime during failures.

By carefully evaluating wattage, voltage compatibility, safety features, durability, and ease of installation, you can select a light pole transformer that ensures reliable operation for years. Remember, the lowest upfront cost isn’t always the best value—prioritize quality, safety, and long-term performance. When in doubt, consult with an electrical engineer or lighting specialist to validate your selection based on site-specific requirements.

Light Pole Transformer Q & A

Q: What is a light pole transformer?

A light pole transformer is a specialized electrical device mounted on or near a streetlight pole that converts high-voltage electricity from the power grid into lower, safer voltages suitable for powering outdoor lighting systems. These transformers are essential for ensuring that lighting fixtures—such as high-pressure sodium (HPS), metal halide, or LED lamps—receive the correct voltage to operate efficiently and safely.

Typically used in municipal, commercial, and residential lighting applications, these transformers help reduce transmission losses and minimize electrical hazards by stepping down utility-level voltages (e.g., 7,200V or 14,400V) to standard operating levels like 120V or 277V. They are designed for outdoor durability, with weather-resistant enclosures and corrosion protection to withstand environmental conditions.

Q: What are the types of light pole transformers?

There are three primary types of transformers used in light pole applications, each serving a distinct electrical purpose:

• Step-Down Transformers: The most common type used in street lighting. These reduce high incoming voltages (from distribution lines) to lower levels required by lighting fixtures (e.g., 120V or 277V). They are crucial for safety and compatibility with standard lighting loads.
• Step-Up Transformers: Less common in typical streetlight setups, these increase voltage output and may be used in specific long-distance lighting runs where voltage drop is a concern, though they are more frequently found in transmission systems than at the pole level.
• Isolation Transformers: Provide electrical separation between input and output circuits without necessarily changing the voltage. They enhance safety by preventing ground loops and reducing the risk of electric shock, making them ideal for wet or high-traffic environments.

Most modern light pole installations use step-down isolation transformers for combined efficiency, safety, and reliability.

Q: What are the advantages of light pole transformers?

Light pole transformers offer several key benefits that make them indispensable in outdoor lighting infrastructure:

• Improved Safety: By reducing high distribution voltages to safer levels, they significantly lower the risk of electric shock to maintenance personnel and the public.
• Energy Efficiency: Properly sized transformers minimize power loss and support efficient operation of lighting systems, especially when paired with modern LED fixtures.
• Versatility: Compatible with various lighting technologies, including LED, HPS, and metal halide, allowing municipalities and contractors flexibility in design and upgrades.
• Reduced Voltage Drop: Local voltage transformation helps maintain consistent light output across long circuits by minimizing voltage drop over distance.
• Cost-Effective Infrastructure: Enables the use of thinner, less expensive wiring since lower voltages can be distributed locally after transformation.
• Durability: Designed for outdoor use with sealed enclosures, UV-resistant coatings, and thermal protection for reliable long-term performance.

Q: What are the disadvantages of light pole transformers?

Despite their many advantages, light pole transformers do come with certain limitations and challenges:

• Heat Generation: Transformers, especially older or overloaded units, can generate significant heat during operation, which may reduce lifespan or pose fire risks if not properly ventilated.
• Humming Noise: Magnetic core vibrations in transformers often produce a low-frequency hum, which can be a nuisance in quiet residential or urban areas.
• Bulk and Weight: Larger transformers can be heavy and bulky, requiring strong mounting structures and complicating installation or replacement, particularly on older or slender poles.
• Maintenance Needs: While generally reliable, transformers can fail due to moisture ingress, lightning strikes, or insulation breakdown, requiring inspection and occasional servicing.
• Initial Cost: High-quality, weatherproof transformers represent a significant upfront investment, though this is often offset by long-term energy and safety benefits.
• Environmental Concerns: Some older units may contain dielectric fluids (e.g., PCBs in very old models), though modern units use environmentally safe materials.

Proper selection, installation, and routine inspection can mitigate most of these drawbacks.

Q: How do light poles powered by LED lighting differ from traditional lighting?

LED-powered light poles differ significantly from those using traditional lighting technologies (like high-pressure sodium or metal halide) in terms of efficiency, transformer requirements, and overall performance:

Feature	Traditional Lighting (HPS/Metal Halide)	LED Lighting
Power Consumption	High (e.g., 150–400W per fixture)	Low (e.g., 50–150W for equivalent light output)
Transformer Size	Larger, higher-capacity transformers needed	Smaller, lower-wattage transformers sufficient
Energy Efficiency	Less efficient (30–50% energy lost as heat)	Highly efficient (up to 80–90% less energy used)
Lifespan	10,000–24,000 hours	50,000–100,000+ hours
Light Quality	Yellowish hue, poor color rendering	Bright white light, excellent color accuracy
Start-Up Time	Warm-up period required (3–5 minutes)	Instant on/off, no warm-up needed

Because LEDs are inherently more energy-efficient and require less power, the associated transformers can be smaller, lighter, and cooler-running. This allows for easier integration into existing poles and reduces strain on the electrical grid. Additionally, many modern LED fixtures include internal drivers that perform localized voltage conversion, further simplifying or even eliminating the need for external pole-mounted transformers in some retrofit applications.