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.

The NEC is about setting safety baselines for electrical work. It provides minimum safety standards for how electrical systems should be installed and maintained, covering wiring methods, overcurrent protection, grounding, conduit use, and device placement. These rules are designed to reduce shock and fire hazards and to help ensure electrical systems operate safely. Jurisdictions adopt the NEC into local law, so following these standards is required where electrical work is performed. It isn’t about fines, medical procedures, or environmental safety—that’s handled by other codes or agencies.

Grounding and bonding are safety practices that ensure fault currents have a clear path to earth and that all metal parts in a system are at the same electrical potential, reducing shock risk and equipment damage. The NEC lays out a dedicated article that explains how to establish a grounding electrode system (like ground rods and other bonded electrodes), how to run equipment grounding conductors from the panel to outlets and equipment, and how to bond non-current-carrying metal parts (such as water piping, gas piping, and structural metal) to maintain a unified electrical potential. This article is the primary reference for requirements and best practices in grounding and bonding, detailing what’s needed for proper safety and system performance. Other parts of the NEC address different topics, such as service conductors and overcurrent protection, conductor sizing and ampacity, and general definitions, but they do not provide the focused rules for grounding and bonding.

A three-way switch has three connection points for conductors, plus a separate ground. The three terminals are one common and two traveler terminals. The common terminal carries either the hot feed or the switched leg to the light, while the traveler terminals connect to the two traveler wires that run to the other switch. Ground is not counted among the terminals. That’s why the standard three-way switch has three terminals. The other counts (two or more than three) don’t match this configuration: two terminals is a simple single-pole switch, and four or five would belong to other, nonstandard or multi-gang arrangements.