A polarized plug is designed to differentiate between which conductors and will fit into a receptacle only one way.

• A. They have three prongs
• B. They can be plugged in any orientation
• C. They include a built-in fuse
• D. They differentiate between grounded and hot conductors and fit only one way

Answer: (D)

Polarization is about identifying which conductor is neutral (grounded) and which is hot, and making sure the plug can only go into the outlet in the correct orientation. A polarized two-prong plug uses one blade that’s wider than the other. The wide blade is the neutral (grounded) conductor, and the narrow blade is the hot conductor. The corresponding outlet slots are sized to match, so the neutral blade only fits into the wider slot and the hot blade into the narrower slot. This forces the device to be connected with the proper polarity, reducing the risk of shock if a fault occurs.

The other ideas aren’t about polarity: a three-prong design adds a ground pin; a fuse is a safety feature but not about blade polarity; plugs designed to fit in any orientation defeat polarization.