You're right, finding clear instructions for grounding to a 4x4 with hammer-on clips can be tricky. The key thing to remember is that wood is not conductive, so the clip needs to create a mechanical bond to the device you're grounding, not the wood itself. Here's a breakdown of the proper approach and things to consider

Understanding the Goal:
Not Grounding the Wood

The 4x4 is simply a mounting point. You're grounding the electrical device (outlet, switch, light fixture, etc.) mounted to the 4x4.

Mechanical Connection

The clip needs to make a secure, low-resistance connection to the grounding screw/terminal of the device.

Steps and Considerations


Identify the Device Ground Terminal

Find the green grounding screw or bare copper wire on the device you're mounting to the 4x4. This is where the ground wire from your circuit will connect.
2.

Prepare the Ground Wire

Strip the insulation from the end of the ground wire (typically bare copper or green insulated) to expose about 1/2" - 3/4" of the conductor. If the wire is stranded, twist the strands tightly together.

Option A (Preferred)

Form the wire into a loop that will fit snugly under the grounding screw head.

Option B

Straighten the wire and prepare it to lay alongside the mounting surface for the hammer clip.3.

Positioning the Hammer-On Clip



Crucially, the clip needs to make good contact with the ground wire and be positioned so the device's grounding screw tightens down on the ground wire loop/end and the clip itself. Place the ground wire next to the device's mounting surface. Position the clip so it clamps securely over the ground wire and sits against the side of the device where the grounding screw will be located. Make sure the clip doesn't interfere with the device's mounting.4. Hammering the Clip

Use a hammer to drive the clip into the 4x4. Be careful not to damage the wire insulation if the wire is insulated. Make sure the clip is firmly embedded in the wood and provides a secure mechanical hold on the wire.5.

Connecting the Ground Wire



If you made a loop

Loosen the grounding screw on the device. Place the loop under the screw head. Tighten the screw securely. The screw should clamp the wire firmly against the body of the device.

If you straightened the wire

The screw should contact the wire being held by the hammer clip when you tighten it. This might require bending the wire slightly to ensure proper contact.6.

Testing (Important!) Continuity Test

Use a multimeter to check for continuity between the device's grounding terminal and the metal box/housing (if applicable). You should have very low resistance (close to 0 ohms). This verifies a good ground connection. If you don't have a multimeter, consider getting one – they're essential for safe electrical work.

Important Safety Notes



Turn Off Power

ALWAYS turn off the power at the circuit breaker before working on any electrical wiring.

Code Compliance

Electrical codes vary. The best practice is to use a metal junction box mounted on the wood and bond the device to the junction box. Consult local codes or a qualified electrician if you're unsure about your specific application.

Secure Mounting

Ensure the electrical device is securely mounted to the 4x4 independently of the grounding clip. The grounding clip provides the electrical connection, not structural support.

Why This Is Tricky



Wood Is an Insulator

Wood doesn't conduct electricity, so you can't ground to the wood. You must create a low-resistance path back to the grounding system through the wiring.*

Alternatives

Consider using a metal junction box attached to the 4x4. This provides a more reliable grounding point and is often preferred or required by code. Connect the ground wire to the box using a grounding screw, then pigtail to the device.

In summary, hammer clips can work in this scenario. The key is to ensure a solid mechanical and electrical connection between the ground wire, the clip, and the device's grounding terminal. Flag for review