About this video:
Transformers are necessary whenever the power supply has to be changed to accommodate a different current load. They are generally located next to a panelboard that requires a different voltage than what is being distributed throughout a building. There are two main types of transformers: step-up and step-down transformers.
- Step-Up Transformer: A step-up transformer increases the voltage. These transformers are used where the voltage is lower than what is needed and the transformer has to increase the voltage to accommodate the need.
- Step-Down Transformer: A step-down transformer decreases voltage. These transformers are used where the voltage is too high and has to be decreased to accommodate the need.
The ComSOP does not require inspectors to inspect the transformers. However, transformers are common, and inspectors should be able to identify them and accurately document basic label information.
To identify the type of transformer, inspectors should check the high and low voltage numbers, also known as primary and secondary voltage ratings. If the primary voltage is greater than the secondary voltage, then it is a step-down transformer. If the primary voltage is lower than the secondary voltage, then it is a step-up transformer.
The primary voltage refers to the input, while the secondary voltage is the output. Generally, if it doesn’t specify “primary,” you can determine the input voltage by referring to the first number listed on the label. Inspectors can trace the conduit from the transformer to learn more about the installation.
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