Everything You Need to Know About Wire Connectors (aka Wire Nuts)
Have you ever wondered how many wires in a wire nut or what types professionals use for different jobs? In this post, we’ll break it all down — from wire nut sizes to safe wiring practices.
The 4 Major Types of Wire Nuts Electricians Use
Professional electricians typically rely on four main types of wire connectors:
- 331s (Small Orange Wire Nuts)
These are the smallest of the bunch and can usually handle:- 2 x #14 gauge wires
- Up to 5 x #18 wires (often used in low-voltage or communication wiring)
- 333s (Blue and Yellow Wire Nuts)
These are the most common for residential use. The yellow version often includes side arms for better grip and torque.- Good for up to 4 x #14 wires
- Ideal for light fixtures or medium-duty connections
- 335s (Red Wire Nuts)
Perfect for larger wire combinations, like multi-wire neutral or hot connections in switch boxes.- Rated for up to 7 x #14 gauge wires
- Commonly used for residential junction boxes with 5–6 wires
- 39s (Large Gray or Red Wire Nuts)
These handle the biggest jobs.- Can connect 4 x #10s, 9 x #14s, and even 2 x #6 gauge wires
- Useful for appliances like stoves or when junctioning heavy loads
How Many Wires Can You Safely Fit?
The number of wires you can safely twist into a connector depends on the manufacturer’s specifications. Always check the side of the box or the packaging — it will show the approved combinations based on wire size and type.
For example:
- A small orange 331 is typically good for just two #14s.
- A red 335 can handle six or seven #14s.
- A 39 can be used for nine #14s or even two #6s for heavy-duty junctions.
Tip: When using 333s for three #14s, strip back about an inch of insulation, twist the wires together counterclockwise, and then install the wire nut clockwise. For extra security, give it another turn with your pliers.
Push-In Wire Connectors: Pros and Cons
Push-in wire connectors (like Wago-style connectors) are becoming more popular, especially for low-amperage applications. However, there are some important considerations:
When to Use Push-Ins:
- Pot lights or slim LED fixtures often come with built-in push connectors.
- Great for low-draw circuits where space is tight.
When to Avoid Push-Ins:
- For high-load devices (like heaters or receptacles), we don’t recommend them.
- The internal clamp provides minimal contact area. Under heavy load, this small point of contact can heat up and melt — a potential fire hazard.
Instead, we recommend:
- Always wrapping wires around screw terminals for receptacles.
- Using traditional wire nuts for connections on circuits with higher loads.
Final Thoughts: Trust the Classic Twist-On
Wire nuts (or “Marettes” as some call them) have stood the test of time. When installed correctly — twisting both the wires and the connector clockwise, and giving it a firm finish with pliers — you’ll get a solid, reliable connection that won’t let you down.
Recap: The Four Wire Nut Types
- 331s: Small orange, good for basic low-load connections
- 333s: Blue/yellow, standard for most light-duty jobs
- 335s: Red, handles 5–7 wires, great for switch boxes
- 39s: Large gray/red, for big connections up to #6 gauge
Always follow manufacturer specs, and when in doubt — go one size up. Stay safe and wire smart!
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