How Does That Work?

Padmount transformer

What are they?

You may see these green “boxes” – or padmount transformers – on a street corner, behind a business or even in your backyard. Their role in the delivery of power to your home is important.

Here’s how they work:

• 1-phase padmount transformer: The transformer inside this “box” steps down voltage from the utility level, usually 8,000 volts, to 120/240 volts, or a secondary voltage. This is the voltage at which customers can use the power in their homes.To send power to a residence, secondary cables are installed from the 120/240 volt side of the transformer and run underground to a customer’s house. These transformers primarily serve residential customers and other small, single-phase loads such as streetlights, traffic signals and signs.
• 3-phase padmount transformer: These transformers are in a much larger green metal “box”. Here, the voltage steps down from utility level, usually 13,800 volts, to a lower voltage, usually 120/208 or 277/480 volts.The power is now usable for customers. Secondary cables are installed, usually by the customer, to connect the secondary side of the transformer to the building. These transformers serve commercial and industrial customers, who have larger power requirements.

It’s important to remember that landscaping around these transformers in your yard must follow specific guidelines to ensure OPPD crews can access the transformer when needed.