The diamond symbol with a T denotes which device?

• A. Low-voltage transformer
• B. Temperature indicator
• C. Terminal block
• D. Thermal switch

Answer: (A)

In electrical drawings, symbols are shorthand that quickly identify the type of device. A diamond shape with a T inside is used to denote a transformer, with the T standing for transformer. This symbol points to a device that steps down line voltage to a lower, safer control voltage, which is common in control circuits to power relays, contactors, and sensors.

Other devices wouldn’t be represented by this diamond-with-T symbol. A temperature indicator is shown with symbols related to temperature measurement or a thermometer, not a transformer symbol. A terminal block appears as a block or block-like symbol indicating the connection points, and a thermal switch is drawn as a switch symbol often associated with a temperature element, not this transformer icon.