A plug top is a movable connector that is connected to electrically powered equipment, whereas a socket is a fixed connector that connects to an electrified electrical circuit that is fixed on equipment or a building structure. The plug is a male connection with projecting pins that fit into holes and female contacts in the socket. Female contacts are included in some plugs and are only utilized to connect to the earth ground. Some plugs have built-in fuses for enhanced safety. In this article, you will find information related to different designs of plug tops for your home.

Plug type A (or NEMA-1)

Two flat live contact pins are positioned in parallel at 12.7 mm on plug type A (or NEMA-1). The connections measure 15,875-18,256 mm in length, 6.35 mm in width, and 1,524 mm in thickness. Plug-top type A is best suited to tiny devices. The plug is not safeguarded against polarity reversal due to its design.

Plug Type B (or NEMA 5-15, 3 pin plug top)

Two flat live contact pins are positioned in parallel on the plug type B (or NEMA 5-15, 3 pin). A protective conductor is provided via an additional offset placed circular contact. The plug is safeguarded against polarity reversal thanks to this design. Because the protective conductor contact is longer than the other two pins, it joins the socket first.

Plug Type C

Type C plugs are CEE 7/17 or contour plugs,

While Type C plugs are CEE 7/16 or Euro plugs.

The contour plug (or CEE 7/17) has two connections, each measuring 19 mm in length and 4.8 mm in diameter, separated by 19 mm. A cut-out is 10 mm above and below the axle on the plug.

It is not protected against polarity reversal since it lacks a protective conductor. Its contacts measure 4 mm in diameter and are spaced 19 mm apart.

Type D Plug Top

Because the earthing contact is slightly longer (20.6 mm) and thicker (7.06 mm) than the two current-carrying connections (length 14.8 mm / diameter 5.08 mm), it is the first to enter the power supply. The plug's design inherently prevents it from polarity reversal however, it is not safe to touch due to the constantly conducting contacts.

Some multi-standard sockets allow for the use of multiple types of plugs; nevertheless, improvised, or unregulated adaptors between incompatible sockets and plugs may not give the same level of safety and performance as an installed socket-plug combination.