Introduction
We've all been there - opening up the breaker box to toggle a switch and seeing a strange, unconnected wire dangling in the back. I used to wonder what on earth that wire was for, and why it wasn't connected to anything. Well, after doing some research and consulting with electricians, I finally got to the bottom of its purpose. And let me tell you, it's not as mysterious or complicated as you might think!
In this comprehensive guide, I'll walk you through everything you need to know about that weird wire, including:
- What it's called and its intended purpose
- Why it's often left disconnected
- When you need to connect it
- How to properly connect it yourself
I'll also cover safety precautions, recommended tools, and step-by-step instructions for connecting the wire. By the end, you'll be able to handle that weird wire with confidence!
What Is That Weird Wire Called?
The technical name for that mysterious unlabeled wire is a "bonding jumper."
The bonding jumper connects the neutral bus bar in your breaker box to the metal chassis of the box itself. This bonds the two together, ensuring that any stray voltage is safely directed to ground.
Without a properly connected bonding jumper, you could have risks like electric shock or fires in the breaker box. So while it may seem harmless dangling there, this little wire plays an important safety role!
Why Is the Bonding Jumper Often Left Unconnected?
If the bonding jumper is so crucial, why do electricians frequently leave it disconnected in new breaker box installations?
There are a couple reasons for this:
- It's redundant when also using armored cable: Most modern breaker boxes are installed using metal-clad "MC armor" cable. The armor already bonds the system, so an additional bonding jumper isn't strictly necessary.
- Lazy electricians: Some electricians fail to make the connection out of laziness or forgetfulness. This introduces safety risks, so it's important to verify the jumper is in place.
While code allows for a detached bonding jumper in certain conditions, best practice is to connect it. A redundant ground never hurts!
When Do You Need to Connect the Bonding Jumper?
Here are the main scenarios that require connecting the bonding jumper:
- New breaker box installation: Always verify the jumper is connected, even if using MC armored cable. This ensures proper bonding per code requirements.
- Older breaker boxes: Older boxes that predate MC cable would rely solely on the jumper for bonding. It must be connected!
- Using unarmored cable: If your system uses plastic-sheathed NM cable instead of MC armored cable, that jumper becomes crucial for safety.
- Jumper was disconnected: If a repair requires disconnecting the jumper, it must be re-attached when the work is complete. Leaving it detached risks safety hazards.
- In doubt, connect it: When in doubt, it's always safer to have the bonding jumper connected. The few minutes it takes are worth it!
Gather the Proper Supplies
Connecting the bonding jumper is a simple task, but having the right tools makes the process easier and safer.
Here are the basic supplies you'll need:
- Insulated screwdrivers: You'll need standard screwdrivers to remove the breaker box cover and disconnect/reconnect the jumper. Make sure they are fully insulated to prevent shocks.
- Wire strippers: To strip back the ends of the jumper wire for reconnection.
- Voltmeter (optional): A non-contact voltmeter can verify the power is off.
- 8 AWG bare copper wire (if adding new jumper): The jumper should be made of thick 8 AWG wire. Often it's already present but detached in the breaker box.
- Wire nuts (if adding new jumper): For securing the jumper connections.
Safety Precautions
Any breaker box work comes with major shock and electrocution risks. Take these precautions:
- Turn off the main breaker! This cuts power to the full breaker box. Verify it's off with a voltmeter.
- Leave cover off until work is complete for visibility.
- No jewelry or conductive objects near the box.
- Only use one hand when working inside the box to avoid complete circuits.
- Supervise children to keep them clear of the box.
- Double check connections before restoring power.
Proceed with great care when working around a live breaker box!
Step-by-Step Instructions
With the right supplies and safety precautions, you're ready to tackle that weird wire! Follow these steps:
1. Turn Off the Main Breaker
Shut off the main breaker that controls all lower breakers in the box. Verify power is cut using a non-contact voltmeter if available.
2. Remove the Breaker Box Cover
Unscrew and remove the metal cover plate to access the interior. Place it aside carefully.
3. Locate the Bonding Jumper
Scan the back interior wall for an unconnected green or bare copper 8 AWG wire dangling loose. This is the bonding jumper you need to connect.
4. Prep the Jumper and Connection Points
Use strippers to remove about 0.5" of insulation from each end of the jumper wire. Also strip any corrosion from the neutral bus and breaker box chassis bonding point.
5. Connect One End to the Neutral Bus
Referring to existing neutral connections, secure one jumper wire end firmly under a neutral bus screw or clamp.
6. Connect the Other End to the Breaker Box
Connect the other jumper end to the bonded breaker box chassis attachment point. Often a green screw is provided for this grounding connection.
7. Secure Connections
Verify both connections are tight and secure. No copper should be exposed. A tug test can confirm they are snug.
8. Replace the Cover
With connections complete, screw the metal cover plate back into place before restoring power.
9. Restore Power
Switch the main breaker back on. Check that any GFCI outlets trip and reset properly to verify functionality.
You Did It!
With the bonding jumper securely re-connected, you've greatly improved the safety of your electrical system. That weird wire is weird no more!
While not the most glamorous task, properly grounding the breaker box is incredibly important for preventing accidents and fires. If you were able to connect that orphan jumper, pat yourself on the back for a job well done.