What Size Ring Terminal Do I Need?
Ring terminals are a type of electrical connector used to attach wires to terminals on electrical equipment and devices. They consist of a circular metal ring on one end that fits around a screw or stud, with a barrel on the other end for connecting and securing the wire.
Ring terminals provide a convenient and reliable way to terminate wires for electrical connections. The metal ring loops around the post or screw, allowing the wire to be firmly secured while still maintaining flexibility for positioning and routing.
Some common applications and uses for ring terminals include:
- Connecting wiring in electrical control panels and junction boxes
- Attaching wires to electrical motors and pumps
- Terminating cable shields and grounds
- Splicing and extending wires through inline connections
- Providing flexible, removable connections for maintenance and repairs
With so many sizes, materials, and options available, selecting the right ring terminal for an application requires understanding wire gauges, terminal current ratings, and installation best practices.
Measuring Wire Gauge
Knowing the wire gauge is crucial for selecting the correct size ring terminal. Wire gauge refers to the diameter or thickness of the individual strands of wire. The American Wire Gauge (AWG) system is the standard for specifying wire gauge. The gauge numbers become smaller as the wire diameter increases. For example, a 10 AWG wire is thicker than a 14 AWG wire.
There are a few ways to measure wire gauge:
- Use a wire gauge tool that has numbered slots that match AWG sizes. Strip a section of the wire and see which slot it fits into snugly.
- Use a caliper or micrometer to precisely measure the diameter of an individual strand. Consult an AWG reference chart to match it to the gauge.
- Look for any labeling printed on the wire insulation that indicates the gauge.
Knowing the exact wire gauge is important because undersized ring terminals can cut into the wire strands, while oversized terminals may not grip the wire tightly enough. Using the proper ring terminal size for the wire gauge ensures a solid mechanical and electrical connection.
Common Wire Gauges
The most common wire gauge sizes used for electrical wiring projects and components are:
- 14 gauge – Used for normal house wiring and lighting circuits. Can handle 15 amps.
- 12 gauge – Used for 20 amp appliance circuits like kitchen outlets, electric water heaters, etc.
- 10 gauge – Used for 30 amp appliance circuits like electric dryers and air conditioners.
- 8 gauge – Used for heavy 40-50 amp appliance circuits like electric ranges and hot water heaters.
- 6 gauge – Used for 60 amp appliance circuits like welders, hot tubs, subpanels.
- 4 gauge – Used for 70-100 amp service entrance wires and high current applications.
- 2 gauge – Used for 100-200 amp service loads like main panels and generators.
- 1/0 gauge – Used for 200-400 amp service entrance wires.
The lower the gauge number, the thicker the wire size. Common sizes used for building wiring are 12, 10, 8, 6, and 4 gauge (source: https://precmfgco.com/wire-gauge-sizes-guide/). The National Electrical Code dictates the proper wire gauge sizes for various amperages.
Matching Ring Terminal Size to Wire Gauge
It is crucial to match the correct ring terminal size to the wire gauge you are using. Using an improperly sized ring terminal can lead to loose connections and overheating. The ring terminal must be large enough to fully seat the wire inside while also matching the terminal screw or stud size.
Here is a reference table showing recommended ring terminal sizes for various wire gauges:
| Wire Gauge | Ring Terminal Size |
|---|---|
| 22 AWG | #6 |
| 20 AWG | #6 |
| 18 AWG | #6 |
| 16 AWG | #6 |
| 14 AWG | #8 |
| 12 AWG | #10 |
| 10 AWG | #12 |
| 8 AWG | 1/4″ |
When selecting a ring terminal, match it to both the wire gauge being used as well as the terminal screw or stud size. Improper sizing can lead to loose and unreliable connections.
Materials
Ring terminals are made from a range of materials, but the most common are:
- Copper – Copper is the most commonly used material for ring terminals. It has excellent electrical conductivity and is corrosion resistant. Copper ring terminals are typically tin-plated to prevent oxidation and improve solderability. They work well in a wide range of applications.
- Steel – Steel ring terminals have high strength and durability. They are typically zinc plated for corrosion resistance. Steel is less expensive than copper but also has lower conductivity. Steel ring terminals work well in high vibration applications.
- Brass – Brass provides a good balance of strength, conductivity, and cost. Brass terminals are nickel-plated for corrosion resistance and conductivity. Brass is suitable for many general purpose applications.
- Aluminum – Aluminum has conductivity nearly equal to copper at a lower cost. However, aluminum is not as strong and corrosion resistant as other metals. Aluminum ring terminals require careful installation to avoid damaging the softer metal.
The optimal material depends on factors like cost, strength needs, corrosion issues, and conductivity requirements. Copper provides the best overall conductivity and corrosion resistance for most applications.
Insulated vs Non-Insulated
Insulated ring terminals have an insulating sleeve or coating that covers the metal terminal, while non-insulated terminals are exposed metal. The key differences are:
Insulation prevents short circuits – The insulation prevents the metal terminal from making contact with other exposed metal surfaces, reducing the risk of short circuits and electrical fires. This makes insulated terminals safer for applications where terminals are in close proximity.
Insulation protects from corrosion – The insulation protects the metal terminal from corrosion and oxidation. This makes insulated terminals suitable for outdoor use or wet environments.
Color coding – Insulated terminals often use colored insulation for circuit identification. This allows easy visual circuit tracing.
Higher cost – Insulated terminals cost more than non-insulated due to the additional manufacturing steps to add insulation.
Lower current rating – The insulation slightly reduces the current carrying capacity of the terminal. Insulated terminals have lower amperage ratings.
Usage – Non-insulated terminals are commonly used for internal wiring connections where short circuiting is not a concern. Insulated terminals are used where exposed live terminals create hazards.
Sources:
https://www.panduit.com/en/products/wire-termination/terminals-terminal-kits/ring-terminals.html
Ring Terminal Current Ratings
The current rating of a ring terminal indicates the maximum amperage it can safely carry. Choosing a ring terminal with the proper current rating for your application is critical to avoid overheating and potential fire hazards.
Current ratings are determined by the size and material of the terminal. Larger wire gauges and ring terminal sizes allow higher amp capacities. Copper terminals offer higher current ratings than aluminum. Insulated terminals derate the capacity slightly.
Below is a general table showing recommended continuous current ratings for various ring terminal sizes and wire gauges:
| Wire Gauge | Ring Terminal Size | Max Amps |
|---|---|---|
| 22-16 AWG | 6mm | 15 |
| 16-14 AWG | 8mm | 20 |
| 14-12 AWG | 10mm | 30 |
| 10 AWG | 12mm | 40 |
Refer to manufacturer specifications for the exact current rating of a specific ring terminal product. Do not exceed the rated amp capacity in your application.
It’s also important to select a wire gauge sufficient for the current rating. Undersized wires can overheat even when connected to an appropriately sized terminal.
Sources:
https://www.mode-elec.com/mode_html/ring.html
https://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=2-1773700-5TerminalAndSplicesSelection&DocType=DS&DocLang=English&s_cid=1046
Installation Tips
When installing ring terminals, follow these best practices for secure and reliable connections:
Use the proper crimping tool matched to the terminal size. Mismatched tools can result in loose terminals that fall off wires. Select a ratcheting crimper for consistent pressure.
Strip the wire insulation properly so the bare wire fully inserts into the terminal barrel with no exposed strands. 1/4″ of bare wire is ideal for most terminals. Do not tin the stripped wire ends.
Make sure the terminal is oriented correctly in the crimper before compressing. The seam on the terminal barrel should face the indenter on the crimper.
Apply even pressure when crimping and hold for a few seconds. Re-crimp if the connection feels loose. Visually inspect for deformities in the crimp shape.
Use heat shrink tubing over exposed terminal barrels for additional insulation and strain relief. Choose appropriately sized tubing for the terminal diameter.
Avoid soldering wires into terminals as this can weaken the crimp over time. Solder any splices first before inserting into the terminal.
Connect ring terminals properly to binding posts or studs with the right size washers, nuts and torque specifications.
Group same or similar gauge wires into one terminal when possible. Do not exceed the current rating.
Test crimped connections for conductivity and secure attachment. Gently tug the wires to verify proper retention.
Applications
Ring terminals are commonly used in a variety of industries and applications including:
Automotive – Ring terminals are frequently used to connect wires to automotive electrical systems like batteries, alternators, lights, and ignition systems. The ring terminal securely fastens the wire while also allowing for easy removal and replacement during repairs (Wiring Products).
Marine – On boats, ring terminals provide corrosion resistant and secure electrical connections exposed to moisture. Common marine applications include bilge pump wiring, navigation lights, trolling motors, and battery connections (Pacer).
HVAC Systems – Heating, ventilation and air conditioning (HVAC) systems rely on many electrical connections. Ring terminals allow wires to be securely attached to contactors, motors, compressors, valves, and control boards (TE Connectivity).
Industrial – Factories use ring terminals to create safe and durable power connections for motors, pumps, compressors, conveyor systems, and other industrial machinery. Color-coded ring terminals help with proper wiring (Wiring Products).
Conclusion
When selecting a ring terminal, it is critical to choose the proper size based on the wire gauge you are using. Mismatching the ring terminal and wire can lead to loose connections and system failures. The key steps are:
- Determine the wire gauge by measuring its diameter or checking the labeling.
- Select a ring terminal that correctly matches that wire gauge. Keep handy charts for the common wire gauges.
- Verify the ring terminal is properly rated for the expected electrical load.
- Use the manufacturer’s crimping tool to securely install the ring terminal.
Following these best practices when sizing and installing ring terminals will result in safe, long-lasting electrical connections.
