Lamp sockets are essential components in lighting fixtures, serving as the bridge between the bulb and the electrical power source. Here’s a detailed exploration of what lamp sockets are, their types, and their functionality.
Basic Function of a Socket
A socket delivers electricity to the bulb. It connects the electrical wiring to the bulb through a hot and neutral contact, completing the circuit that powers the light.
Electrical Flow in a Socket:
- Current Path: Electricity flows from the power source to the hot contact in the socket.
- Bulb Connection: The hot contact touches the base of the bulb, transferring the current into the bulb.
- Completion of Circuit: The current flows through the bulb, exits via the threaded base (neutral contact), and returns to the power source, completing the circuit.
Historical Socket Sizes
Historically, incandescent bulbs used four different socket sizes:
- Candelabra (E-12): Reminiscent of chandelier bulbs and vintage Christmas lights.
- Standard Edison or Medium (E-26): Common household bulb size.
- Intermediate (E-17): Rarely used for indoor lamps.
- Mogul Base: Used for large bulbs in vintage floor lamps.
This guide focuses on Standard Edison (E-26) sockets, but the wiring techniques apply to other socket sizes as well.
Types of Standard Edison Sockets
1. Metal Cap and Shell Sockets:
- Consist of four parts, including the shell and cap.
- Some have UNO threads for attaching shades or shade holders.
- Offer various built-in switch types, including keyless (no switch) and 3-way switches for 3-way bulbs.
- The following is the Hot & Neutral anatomy of inserts.
2. Phenolic Sockets:
- Made from phenolic resin, also used in making billiard balls and pot handles.
- Often used in chandeliers and easy to wire.
- The wide shoulder design accommodates various shades, offering versatile styling options.
Detailed Anatomy of Popular Socket Types
Metal Cap and Shell Sockets:
- Hot Terminal Screw: Connects to the hot wire, transferring electricity to the bulb’s center contact.
- Center Metal Tab (Hot Contact): Touches the bulb’s base to deliver power.
- Threaded Shell (Neutral Contact): Contacts the bulb's threaded base, allowing current to exit the bulb and return to the power source.
Phenolic Sockets:
- Shouldered Design: Provides support for a wide range of lampshades.
- Hot and Neutral Contacts: Function similarly to metal cap sockets, supporting electrical flow through the bulb.
Summary of Electrical Process in Sockets
- Power Source to Socket: Current flows from the power source to the socket’s hot terminal screw.
- Hot Terminal to Bulb: Current passes from the terminal screw to the center metal tab (hot contact).
- Bulb Illumination: Current flows through the bulb, lighting it up.
- Return Path: Current exits the bulb via the threaded base (neutral contact), returns through the neutral terminal screw, and completes the circuit back to the power source.
Lamp sockets are vital in lighting, supporting the bulb and ensuring a safe, functional electrical connection. Understanding their components and how they work can enhance your ability to select and maintain lighting fixtures effectively.
