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Safety Cue
Task-specific safety guidance for ordinary work hazards.
Project 08
Bond Metal Boxes and Ground a Branch Circuit
Complete and verify the equipment-grounding and metal-box bonding path for one de-energized branch-circuit assembly, using listed grounding screws, clips, and connectors, so that every device and metal enclosure installed later in this book shares one continuous, isolated, and tested grounding path back to the source.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become shock, arc flash, or an unproven grounding path.
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Critical Safety Cue
Serious injury, shock, electrocution, or arc flash is possible.
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Field Safety Cue
Practical work-area safety: lighting, footing, access, and housekeeping.
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Code Alert
Local requirements vary. Verify permit, inspection, and jurisdictional rules.
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Manufacturer Cue
Follow product-specific instructions for grounding screws, clips, and connectors.
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Measurement Cue
Reference-point, verification, and continuity-test guidance.
Job Overview
This project qualifies you to complete and verify the equipment-grounding and metal-box bonding path for one de-energized branch-circuit assembly. The finished work product is one metal box, correctly bonded with a listed grounding screw or clip, containing a joined equipment-grounding splice, a box-bonding pigtail, and a device-grounding pigtail where required, with continuity verified from the device yoke and metal box back to the branch equipment-grounding path by a de-energized continuity test.
You will identify each equipment-grounding conductor and distinguish it from the grounded neutral conductor; install a listed grounding screw, clip, or bonding device in the metal box; join incoming and outgoing equipment-grounding conductors; add box-bonding and device-grounding pigtails; terminate them at the correct points; keep the neutral conductor isolated from the box and grounding path; and verify continuity with an approved meter before reassembling the box.
This project builds directly on the box installation of Chapters 3 and 4, the connectors of Chapter 5, the cable of Chapter 6, and the splicing and pigtailing of Chapter 7. It is a prerequisite for every device installed later in this book — the duplex receptacle of Chapter 9, the GFCI receptacle of Chapter 10, the switches and fixtures of Chapters 11 through 15, and the Chapter 20 capstone all depend on a metal box that has already been correctly bonded and grounded using this exact procedure.
Skills You Will Demonstrate
- EL-043 — Identify each equipment-grounding conductor in a branch-circuit assembly and distinguish it from the grounded neutral conductor.
- EL-044 — Install a listed grounding screw, grounding clip, or approved bonding device in a metal box.
- EL-045 — Bond a metal box by joining incoming and outgoing equipment-grounding conductors with an approved connector and pigtail.
- EL-046 — Attach device-grounding pigtails at the green grounding terminal without exceeding the terminal's listed conductor limit.
- EL-047 — Verify grounding continuity from the device yoke and metal box to the branch equipment-grounding path using a de-energized continuity test.
- EL-048 — Inspect the completed grounding path for isolation from the neutral conductor, correct termination, and continuity.
Where This Skill Fits
The grounding and bonding work performed here is what makes a metal box, a device, and every later fixture in this book safe to touch under a fault condition. A box with cable connectors seated and conductors spliced, as completed in Chapters 5 through 7, is not yet a safe assembly until its metal parts are bonded and its equipment-grounding path is proven continuous. Every receptacle, switch, fixture, fan, and exterior device installed in Chapters 9 through 15 terminates its grounding conductor at the pigtail and grounding screw installed in this chapter.
The de-energized continuity test taught here is the same verification method used again in the Chapter 17 diagnostic project, where an open or high-resistance grounding path is one of the conditions a learner must be able to recognize and correct.
Scope and Intended Use
This project covers:
- identifying equipment-grounding conductors and distinguishing them from grounded neutral conductors in a de-energized assembly
- installing a listed grounding screw, grounding clip, or bonding device in a metal box
- joining incoming and outgoing equipment-grounding conductors with an approved connector
- adding and terminating box-bonding and device-grounding pigtails
- keeping neutral conductors isolated from the metal box and equipment-grounding path downstream of the service bonding point
- performing a de-energized continuity test to verify the completed grounding path
This project does not authorize the learner to:
- perform any part of this procedure on an energized circuit
- use a sheet-metal screw, device mounting screw, or any unlisted fastener as the grounding connection
- install a neutral-to-ground jumper or bootleg ground under any circumstance
- energize the assembly before an open, high-resistance, or uncertain grounding path has been investigated and corrected
Any grounding path that fails the continuity test in this chapter must be corrected before the box is reassembled or the assigned device is installed.
Reference Conventions
Establish these references before any conductor is joined or terminated, and do not change the defined grounding scheme mid-project.
| Term | Definition |
|---|---|
| Equipment-grounding conductor | The bare or green-insulated conductor that provides a fault-current path back to the source; not the same conductor as the grounded neutral |
| Box-bonding pigtail | The short conductor connecting the metal box's grounding screw or clip to the joined equipment-grounding conductors |
| Device-grounding pigtail | The short conductor connecting the device's green grounding terminal to the joined equipment-grounding conductors, separate from the box-bonding pigtail where required |
| Bonding point | The location where the box, device, and equipment-grounding conductors are joined to a common, continuous path |
| Bootleg ground | An improper jumper connecting the neutral terminal to the grounding terminal or metal box in place of a real equipment-grounding path; never used in this project |
| Continuity test | A de-energized resistance measurement confirming an unbroken conductive path from the device yoke and metal box to the branch equipment-grounding path |
Grounding Assembly Record
Before joining any grounding conductor, record the assembly identity and design basis directly on the Grounding and Bonding Verification Worksheet:
Work boundary (box / device location): ______ Box type: ______ Grounding method (screw / clip / bonding device): ______
Wiring method and conductor material: ______ Device-grounding pigtail required: ______ (Yes/No) Date started: ____________ Builder name: ____________
Prerequisites
- A completed Electrical Safety-Readiness Worksheet from Chapter 1 confirming the branch circuit is isolated, locked out, and verified de-energized
- A metal box installed per Chapter 3 or 4, with connectors and cable installed per Chapters 5 and 6, and conductors spliced and pigtailed per Chapter 7
- The approved grounding design identifying conductor material and size, box type, device type, and the upstream grounding path
- Listed grounding screws, clips, pigtails, and connectors matched to the box, device, and conductor material
- A continuity-capable multimeter and the tools listed in the Tools, Equipment, Materials, and PPE tables above
Common Field Fundamentals
Every metal box in this book depends on the same grounding logic: identify the equipment-grounding conductor, bond the box to it with a listed device, pigtail the device to it separately where required, and prove the path continuous before covering or energizing anything.
Conductor IDEquipment-grounding conductors identified and distinguished from grounded neutral conductors
Box bondingListed grounding screw, clip, or bonding device installed in the metal box
Splice and pigtailIncoming and outgoing grounding conductors joined; box and device pigtails added
TerminationBox pigtail at the grounding screw or device; device pigtail at the green terminal, one conductor per listed terminal
Neutral isolationNeutral conductors kept isolated from the box and grounding path downstream of the service bonding point
Continuity testDe-energized meter test confirming a continuous path from yoke and box to the branch grounding path
CorrectionOpen, high-resistance, or uncertain paths investigated and corrected before energization
DocumentationGrounding components, continuity results, and corrections recorded on the worksheet
Distinguishing Equipment-Grounding Conductors from Neutral Conductors
Identify each conductor from the approved circuit documentation before touching any terminal. The equipment-grounding conductor is bare or green-insulated and carries fault current back to the source; it is never the same conductor as the grounded neutral, and the two must remain isolated from each other downstream of the service bonding point. Confusing the two, or bonding them together at a device box, creates a bootleg ground and a false-safe condition.
EL-043 – EL-048
Grounding / Bonding / Continuity Verification Qualification
Bond Metal Boxes and Ground a Branch Circuit
A. Finished-Project Specification
Quantity: one metal box assembly, bonded with a listed grounding screw, clip, or bonding device; equipment-grounding conductors joined with an approved connector; box-bonding pigtail and device-grounding pigtail installed as required by the design; continuity verified from the device yoke and metal box to the branch equipment-grounding path; and documented on one completed Grounding and Bonding Verification Worksheet.
B. Component Schedule
| Component | Quantity | Material | Finished Size | Preparation |
|---|---|---|---|---|
| Grounding screw or clip | 1 per metal box | Listed green grounding screw or grounding clip per manufacturer instructions | As supplied by manufacturer | Installed in the box's designated grounding hole or slot; not substituted with a sheet-metal or device-mounting screw |
| Box-bonding pigtail | 1 per metal box | Conductor material and gauge matching the branch equipment-grounding conductor | Length sufficient to reach the grounding screw with the required free length in the box | Stripped to the connector-controlled length; one end at the grounding screw, one end at the grounding splice |
| Device-grounding pigtail | 1 per device, where required | Conductor material and gauge matching the branch equipment-grounding conductor | Length sufficient to reach the device green terminal with the required free length | Stripped to the connector-controlled length; one end at the device green terminal, one end at the grounding splice |
| Grounding splice connector | 1 per grounding splice point | Listed wire connector rated for the conductor count, material, and gauge present | As supplied by manufacturer | Installed per manufacturer's twist, lever, push-in, or crimp method; not reused if single-use |
C. Material Takeoff
- Grounding hardware: one listed green grounding screw or grounding clip per metal box, matched to the box's manufacturer instructions.
- Pigtail conductor: sufficient bare or green-insulated conductor, matching the branch equipment-grounding conductor material and gauge, for one box-bonding pigtail and, where required, one device-grounding pigtail.
- Connectors: listed wire connectors sized for the total conductor count and material at each grounding splice point.
- Documentation: one Grounding and Bonding Verification Worksheet per assembly, plus a photograph of the completed grounding path before the cover or device is installed.
D. Acceptance Standards
| Check | Standard |
|---|---|
| Conductor identification | Equipment-grounding conductors correctly identified and kept isolated from grounded neutral conductors throughout the assembly |
| Box bonding | Listed grounding screw, clip, or bonding device installed in the metal box; no sheet-metal, device-mounting, or unlisted fastener used |
| Splice condition | Incoming and outgoing equipment-grounding conductors joined with a listed connector, correctly seated with no exposed copper beyond the connector |
| Pigtail termination | Box pigtail terminated at the grounding screw or device; device pigtail terminated at the green terminal with no more conductors under the terminal than listed |
| Neutral isolation | No neutral-to-ground jumper or bootleg ground present anywhere in the assembly |
| Continuity | De-energized continuity test confirms an unbroken path from the device yoke and metal box to the branch equipment-grounding path |
| Documentation | Grounding and Bonding Verification Worksheet complete with components, continuity results, and any corrections recorded |
E. Design Review and Conductor Identification
- Review the approved grounding design, wiring method, conductor material and size, box type, device type, and upstream grounding path. Record this information on the Grounding and Bonding Verification Worksheet before proceeding.
- Verify the circuit is de-energized using the approved test procedure. Use the live-dead-live sequence from Chapter 1 at the target conductors before touching any splice or terminal.
- Identify each equipment-grounding conductor and distinguish it from grounded neutral conductors. Confirm identification against the approved circuit documentation before proceeding.
F. Box Inspection and Grounding Hardware Installation
- Inspect metal boxes, connectors, raceways, grounding screws, clips, bushings, and devices for listed grounding provisions. Confirm the box has a designated, undamaged grounding hole or slot.
- Remove paint, debris, or corrosion only from designated bonding locations. Do not scrape or damage surfaces outside the designated bonding point.
- Install the listed green grounding screw, grounding clip, or approved bonding device in the metal box. Seat it fully per the manufacturer's instructions.
- Do not use a sheet-metal screw, device mounting screw, or unlisted fastener as the grounding connection. Verify this before continuing to the next step.
G. Grounding Splice and Pigtail Installation
- Join incoming and outgoing equipment-grounding conductors with the approved connector. Confirm the connector is listed for the exact conductor count and material present.
- Add a box-bonding pigtail of the correct material and size. Include it in the same grounding splice as the incoming and outgoing conductors.
- Add a separate device-grounding pigtail where required. Confirm whether the project design requires a pigtail independent of the box-bonding pigtail before terminating either.
H. Termination and Neutral Isolation
- Terminate the box pigtail under the listed grounding screw or device. Confirm the connection is tight and the conductor is fully seated.
- Terminate the device pigtail at the green grounding terminal without placing more conductors under the terminal than listed. Check the terminal's listed conductor limit before terminating.
- Keep neutral conductors isolated from the metal box and equipment-grounding path downstream of the service bonding point. Confirm no neutral conductor terminates at the grounding screw, box, or grounding splice.
- Inspect metal cable connectors and raceway fittings for required bonding continuity. Confirm each connector and fitting maintains a continuous metallic path where the design requires it.
- Arrange grounding conductors so they remain connected when the device is removed where required by the design. Confirm the box-bonding pigtail is independent of the device-grounding pigtail where this is required.
I. Continuity Verification and Reassembly
- Perform a de-energized continuity test using an approved meter and isolated test conditions. Confirm the circuit remains de-energized and disconnected from other sources before testing.
- Confirm continuity from device yoke and metal box to the branch equipment-grounding path. Record the measured result on the worksheet.
- Investigate and correct open, high-resistance, or uncertain paths before energization. Do not proceed until the corrected path retests successfully.
- Do not install a neutral-to-ground jumper or bootleg ground. Confirm this a second time before closing the box.
- Reassemble the box and install the cover or assigned device. Fold conductors into the box without stressing the grounding splice or pigtails.
- Document grounding components, continuity results, and corrections. Complete every field on the Grounding and Bonding Verification Worksheet before beginning the next project.
Common Readiness Inspection
Inspect every completed grounding assembly using the same checks regardless of which box, device, or circuit the project involves.
- Identification check: confirm every equipment-grounding conductor was correctly identified and kept isolated from grounded neutral conductors.
- Bonding check: confirm a listed grounding screw, clip, or bonding device is installed in the metal box, with no unlisted fastener substituted.
- Splice check: confirm incoming, outgoing, and pigtail grounding conductors are joined with a listed connector, correctly seated with no exposed copper beyond the connector.
- Termination check: confirm the box pigtail is terminated at the grounding screw or device, and the device pigtail is terminated at the green terminal without exceeding its listed conductor limit.
- Isolation check: confirm no neutral-to-ground jumper or bootleg ground is present anywhere in the assembly.
- Continuity check: confirm the de-energized continuity test shows an unbroken path from the device yoke and metal box to the branch equipment-grounding path.
- Documentation check: confirm the Grounding and Bonding Verification Worksheet is fully completed and signed.
Complete the Grounding and Bonding Verification Worksheet in the Inspection Checklist section below before beginning Project 09.
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Failure Points and Troubleshooting
Cleanup
This project ends with the grounding and bonding path complete, tested, and either covered or ready for the assigned device installation.
- Confirm the metal box remains de-energized until the assigned device or cover installation and required inspection are complete
- Store the continuity-capable multimeter and hand tools in a protected, undamaged condition
- Confirm all grounding splices and pigtails remain seated and undisturbed inside the box
- Store unused grounding screws, clips, pigtail stock, and connectors for the next assigned project
- Store the Grounding and Bonding Verification Worksheet with the Chapter 1 Electrical Safety-Readiness Worksheet for reference by later projects
Field Terms
- Equipment-Grounding Conductor
- The bare or green-insulated conductor providing a fault-current path back to the source, distinct from the grounded neutral conductor.
- Box-Bonding Pigtail
- The short conductor connecting a metal box's grounding screw or clip to the joined equipment-grounding conductors.
- Device-Grounding Pigtail
- The short conductor connecting a device's green grounding terminal to the joined equipment-grounding conductors, kept separate from the box-bonding pigtail where required.
- Bonding Point
- The location where the box, device, and equipment-grounding conductors are joined to a common, continuous path.
- Bootleg Ground
- An improper jumper connecting the neutral terminal to the grounding terminal or metal box in place of a real equipment-grounding path.
- Continuity Test
- A de-energized resistance measurement confirming an unbroken conductive path from the device yoke and metal box to the branch equipment-grounding path.
- Service Bonding Point
- The point at the service equipment where the grounded neutral and equipment-grounding system are connected; neutral and grounding conductors must remain isolated from each other downstream of this point.
- Grounding and Bonding Verification Worksheet
- The document recording grounding components, continuity test results, and any corrections made during this project.
Skill Check
- Why must the equipment-grounding conductor and the grounded neutral conductor remain isolated from each other downstream of the service bonding point?
- Why is a sheet-metal screw or device mounting screw never an acceptable substitute for a listed grounding screw?
- What is a bootleg ground, and why can it cause a plug-in tester to show a false "correctly wired" result?
- Why must a box-bonding pigtail sometimes be installed independently of a device-grounding pigtail?
- What must the learner do if a de-energized continuity test shows an open or high-resistance grounding path?
- Why is a continuity test required in addition to simply installing and terminating the grounding conductors?
- What conditions require paint, debris, or corrosion to be removed from a metal box before bonding?
- Why must the circuit be verified de-energized before this project begins, even though Chapter 1's shutdown was already completed?
- What information must be recorded on the Grounding and Bonding Verification Worksheet before a later chapter project may begin?
- Why does discovering a bootleg ground on existing wiring count as a stop-work condition?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| EL-043 | Identifies each equipment-grounding conductor in a branch-circuit assembly and distinguishes it from the grounded neutral conductor | |||
| EL-044 | Installs a listed grounding screw, grounding clip, or approved bonding device in a metal box without substituting an unlisted fastener | |||
| EL-045 | Bonds a metal box by joining incoming and outgoing equipment-grounding conductors with an approved connector and pigtail | |||
| EL-046 | Attaches device-grounding pigtails at the green grounding terminal without exceeding the terminal's listed conductor limit | |||
| EL-047 | Verifies grounding continuity from the device yoke and metal box to the branch equipment-grounding path using a de-energized continuity test | |||
| EL-048 | Inspects the completed grounding path for isolation from the neutral conductor, correct termination, and continuity, correcting any deficiency found |
Mark one column per competency. Only Demonstrated Independently awards the competency; Demonstrated with Assistance authorizes additional supervised practice but does not complete the requirement.
Inspection Checklist — Grounding and Bonding Verification Worksheet
| Item | Target Condition | Result | Pass/Fail | Correction (if any) |
|---|---|---|---|---|
| Conductor identification | Equipment-grounding conductors identified and isolated from grounded neutral conductors | |||
| Box bonding | Listed grounding screw, clip, or bonding device installed; no unlisted fastener used | |||
| Splice condition | Incoming, outgoing, and pigtail grounding conductors joined with a listed connector, no exposed copper beyond it | |||
| Pigtail termination | Box pigtail at grounding screw or device; device pigtail at green terminal within listed conductor limit | |||
| Neutral isolation | No neutral-to-ground jumper or bootleg ground present | |||
| Continuity test | Unbroken path confirmed from device yoke and metal box to branch equipment-grounding path |
Unresolved grounding conditions and correction plan: ____________________________________________
Grounding path declared complete: ______ (Pass/Fail) Date: ____________ Builder name: ____________
Performance Check
With the equipment-grounding conductors identified, the metal box bonded with a listed grounding screw or clip, the box-bonding and device-grounding pigtails terminated, neutral conductors kept isolated, and continuity verified, review the finished grounding assembly against the Acceptance Standards table and confirm every equipment-grounding conductor is correctly identified and isolated from the neutral, the box is bonded with a listed device rather than an unlisted fastener, every splice and pigtail termination is correctly seated with no exposed copper beyond the connector, no neutral-to-ground jumper or bootleg ground exists anywhere in the assembly, and the de-energized continuity test confirms an unbroken path from the device yoke and metal box to the branch equipment-grounding path. Complete the Grounding and Bonding Verification Worksheet and correct any failed item before beginning Project 09. If an item fails, identify whether the error occurred in conductor identification, box bonding, splicing, termination, or neutral isolation before correcting it and re-running the affected continuity check.
Project Closeout
You have completed the eighth project in the residential electrical sequence: bonding metal boxes and grounding a branch circuit. This project required you to identify equipment-grounding conductors and distinguish them from grounded neutral conductors, install listed grounding screws and clips, bond and pigtail the metal box and device, keep neutral conductors correctly isolated, and verify the completed grounding path with a de-energized continuity test (EL-043 through EL-048).
You now have a metal box with a proven, continuous, correctly isolated equipment-grounding path, ready to receive the duplex receptacle, GFCI receptacle, switches, and fixtures installed in the projects that follow. That system carries directly into the next project: installing and testing a duplex receptacle on this de-energized, grounded, inspected branch circuit.
Keep the circuit de-energized and locked out, and retain your Grounding and Bonding Verification Worksheet alongside your Chapter 1 Electrical Safety-Readiness Worksheet. You will reference both records before every remaining device and fixture project in this book.