A dark display does not prove that all power is absent. Auxiliary supplies, externally powered control terminals, stored DC-link energy and connected machinery require identification and a qualified verification procedure. Follow the actual model discharge instructions; elapsed time alone is not proof.
This is reference content written and revised with AI. It has not been verified or approved by a professional. Review by a suitably qualified professional and site authorization are required before use.
Stop before starting
Hold work for unidentified supplies, uncertain stored energy, missing electrical or machine isolation, unsuitable test equipment or unapproved wiring changes. Stop any unexpected response; automatic operation remains on hold until restoration and authorization are complete.
1. Legal and technical scope
| Basis | Scope and limits |
|---|---|
| OSHA 1910.333 | Electrical safe work, isolation, verification and controlled reenergization. |
| OSHA 1910.147 | Hazardous-energy controls for covered machine servicing; electrical scope must also be resolved. |
| OSHA 1926.417 | Construction circuit lockout and tagging within scope. |
For general-industry electrical work, apply 1910.333 within its scope, including qualified verification of deenergization. Machine servicing may also require 1910.147 hazardous-energy controls. Construction electrical work requires the applicable Part 1926 provisions, including 1926.417; do not substitute one regulatory scope for another. Review State Plan requirements and actual equipment instructions.
2. Scope and required inputs
Included work
Identification, isolation, power/control/protective-earth wiring and deenergized checks in a motor control center, followed by preparation for separately authorized functional testing and documented restoration.
Separate assessment
Energized wiring, internal live maintenance, improvised safety-interlock bypass and unapproved motor or automatic-operation tests are excluded.
| Required input | Evidence to obtain |
|---|---|
| Identify circuits and machine | Drawing and motor IDs; External supplies; Safety functions; Test and restoration plan |
| Isolate and verify | Locks and source points; Model discharge basis; Test method and result; Machine safe state |
| Inspect units and space | Unit identity and rating; Support and condition; Tool inventory; Adjacent boundary |
| Wire power and earth | Crimp and terminal type; Fastening evidence; Phase and earth checks; Bend and strain relief |
No actual equipment model, SDS, site measurements, design calculations or authorization record was supplied. Product-specific limits and methods must be verified before use. Federal OSHA is a baseline within its scope; determine the applicable State Plan and local requirements. Manufacturer guidance is not government approval; an incorporated standard differs from voluntary guidance. No nationwide-compliance or expert-approval claim is made.
3. Eight-stage JSA
| Job stage | Hazards and effects | Failure factors | Technical and procedural controls | Site verification | P | S | R | A |
|---|---|---|---|---|---|---|---|---|
| 1. Identify circuits and machine | 1. Wrong motor motion2. Remote start3. Control backfeed4. Protection failure | 1. Drawing outdated2. Inputs omitted3. Auxiliary feed missed4. Settings unreviewed | 1. Match drawing revisions2. Trace every source3. Define machine boundary4. Plan test authority | 1. Drawing and motor IDs2. External supplies3. Safety functions4. Test and restoration plan | ||||
| 2. Isolate and verify | 1. Electric shock2. Stored-energy arc3. Machine movement4. False safe state | 1. Display trusted2. DC energy remains3. Mechanical energy missed4. Tester unsuitable | 1. Apply source isolation2. Follow discharge method3. Control machine energy4. Use qualified verification | 1. Locks and source points2. Model discharge basis3. Test method and result4. Machine safe state | ||||
| 3. Inspect units and space | 1. Unit drop2. Insulation damage3. Debris short4. Adjacent live contact | 1. Unit unsupported2. Damage overlooked3. Metal scraps left4. Boundary unclear | 1. Support removable units2. Check ratings and damage3. Control tools and debris4. Protect adjacent circuits | 1. Unit identity and rating2. Support and condition3. Tool inventory4. Adjacent boundary | ||||
| 4. Wire power and earth | 1. Hot terminal2. Wrong rotation3. Lost earth path4. Cable damage | 1. Crimp mismatch2. Phase ID wrong3. Earth omitted4. Bend or strain excessive | 1. Use specified terminals2. Identify phases3. Verify protective earth4. Provide cable support | 1. Crimp and terminal type2. Fastening evidence3. Phase and earth checks4. Bend and strain relief | ||||
| 5. Wire controls and signals | 1. Unexpected start2. Safety failure3. Signal interference4. External voltage | 1. Terminal confused2. Bypass improvised3. Routing mixed4. Common misunderstood | 1. Match terminal schedule2. Preserve safety design3. Segregate signal routes4. Follow shield scheme | 1. Terminal and wire IDs2. Safety-circuit checks3. Route and separation4. Shield and common basis | ||||
| 6. Perform dead checks | 1. Electronics damage2. Wrong test conclusion3. Tool-caused short4. Cover omitted | 1. Test voltage wrong2. Continuity overclaimed3. Tools uncounted4. Guard left off | 1. Use approved test method2. Separate function testing3. Reconcile tools4. Restore required covers | 1. Test connections2. Results and limits3. Electronics protection4. Tools and covers | ||||
| 7. Control functional test | 1. Remote machine motion2. Arc exposure3. Unsafe correction4. False protective action | 1. People not clear2. Test boundary absent3. Live correction attempted4. Force untracked | 1. Authorize each test state2. Clear machine envelope3. Re-isolate for changes4. Log temporary overrides | 1. Test state and authority2. Expected actual response3. Force and jumper log4. Renewed isolation | ||||
| 8. Restore and hand over | 1. Automatic start2. Protection bypass3. Wrong settings4. Uninformed operator | 1. Normal mode assumed2. Jumper remains3. Version not restored4. Handover absent | 1. Use restoration sequence2. Reconcile temporary items3. Verify approved settings4. Obtain operation release | 1. Restoration inventory2. Normal-mode checks3. Guard and people status4. Recipient and authority |
P = likelihood; S = severity; R = risk under the site method; A = site-defined acceptance/authorization. These actual assessment cells are blank. A low score never overrides a missing safeguard or a legal or manufacturer restriction.
4. Fictional scenario and failure mechanisms
This illustration provides educational context. It is not an actual incident photograph or evidence of equipment suitability; any AI-generated depiction is illustrative only.
The scenario and record comparisons are fictional teaching examples, not records of real incidents, measurements, inspections, signatures or approvals.
| Stage | Fictional situation |
|---|---|
| Initial situation | A fictional crew completes a successful local motor test. |
| Changed condition | The next shift requests automatic operation. |
| Failure path | Temporary forced values and remote start inputs have not been reconciled. |
| Possible outcome | A machine could start unexpectedly or operate without an intended protective function. |
| Prevention barrier | Hold automatic release, reconcile every temporary change, restore the approved configuration and verify the required states with machinery safeguards and personnel clear. |
Failure mechanisms
A dark display does not prove that all power is absent. Auxiliary supplies, externally powered control terminals, stored DC-link energy and connected machinery require identification and a qualified verification procedure. Follow the actual model discharge instructions; elapsed time alone is not proof.
Point-to-point continuity is not a functional test of a safety circuit, motor direction or every automatic state. Insulation-test connections and voltage must suit the equipment; connected drives and electronics may require disconnection under their instructions.
Temporary jumpers, forced logic values and changed settings need an inventory and an approved restoration sequence. Removing them indiscriminately can itself cause movement. Each energized test needs a cleared machine boundary and authority; corrections require renewed isolation and verification.
Work sequence: Identify circuits and machine → Isolate and verify → Inspect units and space → Wire power and earth → Wire controls and signals → Perform dead checks → Control functional test → Restore and hand over. This is a teaching flow, not a device drawing or a complete operating procedure.
5. Conditional decisions and common errors
| Situation | Required action | Evidence | Proceed when |
|---|---|---|---|
| Auxiliary source unknown | Hold wiring | Supply tracing and isolation record | All sources controlled |
| Insulation test proposed | Check equipment compatibility | Model, connections and test method | Method accepted |
| Test result differs | Stop test and isolate | Expected versus actual response | Correction verified |
| Automatic mode requested | Reconcile temporary changes | Forces, jumpers and safeguards | Operation authorized |
Similar observations, different decisions
The scenario and record comparisons are fictional teaching examples, not records of real incidents, measurements, inspections, signatures or approvals.
| Observation | Insufficient conclusion | Required distinction |
|---|---|---|
| Display off | Control indication | Electrical safe state unproved |
| Continuity passes | Circuit path checked | Safety function unproved |
| Local test passes | One operating state | Automatic release separate |
6. Roles and responsibilities
| Role | Responsibility |
|---|---|
| Work supervisor | Confirm drawing and motor ids and the task scope, resources, interfaces and stop authority. |
| Qualified technical reviewer | Review locks and source points, model limits, compatibility and unresolved technical conditions within assigned competence. |
| Work crew | Apply the listed controls, report changes and stop when evidence or safeguards are missing. |
| Inspector / assessor | Record actual terminal and wire ids and other relevant checks; do not mark unverified conditions as accepted. |
| Handover authority | Reconcile restoration inventory, restrictions and outstanding actions before the next task. Role labels do not establish a legal credential. |
Supervision and handover focus
| Stage | Management action | Evidence |
|---|---|---|
| Identify circuits and machine | 1. Record drawing and motor ids2. Record external supplies3. Record safety functions | 1. Drawing and motor IDs2. External supplies3. Safety functions |
| Isolate and verify | 1. Record locks and source points2. Record model discharge basis3. Record test method and result | 1. Locks and source points2. Model discharge basis3. Test method and result |
| Wire power and earth | 1. Record crimp and terminal type2. Record fastening evidence3. Record phase and earth checks | 1. Crimp and terminal type2. Fastening evidence3. Phase and earth checks |
| Wire controls and signals | 1. Record terminal and wire ids2. Record safety-circuit checks3. Record route and separation | 1. Terminal and wire IDs2. Safety-circuit checks3. Route and separation |
| Control functional test | 1. Record test state and authority2. Record expected actual response3. Record force and jumper log | 1. Test state and authority2. Expected actual response3. Force and jumper log |
| Restore and hand over | 1. Record restoration inventory2. Record normal-mode checks3. Record guard and people status | 1. Restoration inventory2. Normal-mode checks3. Guard and people status |
7. Hold points and record comparison
| Hold point | Evidence before release | Actual approval |
|---|---|---|
| HP-0 Scope | Identification, isolation, power/control/protective-earth wiring and deenergized checks in a motor control center, followed by preparation for separately authorized functional testing and documented restoration. | |
| HP-1 Isolate and verify | Locks and source points; Model discharge basis; Test method and result; Machine safe state | |
| HP-2 Wire power and earth | Crimp and terminal type; Fastening evidence; Phase and earth checks; Bend and strain relief | |
| HP-3 Control functional test | Test state and authority; Expected actual response; Force and jumper log; Renewed isolation | |
| HP-4 Restore and hand over | Restoration inventory; Normal-mode checks; Guard and people status; Recipient and authority |
Hold points are internal project checks. They are not universal statutory permits and do not grant work permission. Reassess after defects, changed conditions and shift changes.
Record comparison
The scenario and record comparisons are fictional teaching examples, not records of real incidents, measurements, inspections, signatures or approvals.
The boxes are static record prompts, not interactive or saved approvals. A tick does not establish suitability or permission to restart. Record the evidence, person, time and unresolved issues; retain the change history.
| Record | Insufficient record | Record checklist |
|---|---|---|
| Identify circuits and machine | Only marked “OK” | □ Drawing and motor IDs□ External supplies□ Safety functions□ Test and restoration plan |
| Wire power and earth | Only marked “OK” | □ Crimp and terminal type□ Fastening evidence□ Phase and earth checks□ Bend and strain relief |
| Control functional test | Only marked “OK” | □ Test state and authority□ Expected actual response□ Force and jumper log□ Renewed isolation |
| Restore and hand over | Only marked “OK” | □ Restoration inventory□ Normal-mode checks□ Guard and people status□ Recipient and authority |
8. Site checklist and emergency response
| Site check | Actual result | Person / action |
|---|---|---|
| Identify circuits and machine: Drawing and motor IDs; External supplies; Safety functions; Test and restoration plan | ||
| Isolate and verify: Locks and source points; Model discharge basis; Test method and result; Machine safe state | ||
| Inspect units and space: Unit identity and rating; Support and condition; Tool inventory; Adjacent boundary | ||
| Wire power and earth: Crimp and terminal type; Fastening evidence; Phase and earth checks; Bend and strain relief | ||
| Wire controls and signals: Terminal and wire IDs; Safety-circuit checks; Route and separation; Shield and common basis | ||
| Perform dead checks: Test connections; Results and limits; Electronics protection; Tools and covers | ||
| Control functional test: Test state and authority; Expected actual response; Force and jumper log; Renewed isolation | ||
| Restore and hand over: Restoration inventory; Normal-mode checks; Guard and people status; Recipient and authority |
Stop work
Hold work for unidentified supplies, uncertain stored energy, missing electrical or machine isolation, unsuitable test equipment or unapproved wiring changes. Stop any unexpected response; automatic operation remains on hold until restoration and authorization are complete.
Emergency response
Keep people clear of exposed circuits and moving machinery. Use the established emergency isolation and response plan; do not touch a person or equipment still exposed to electrical energy. Qualified personnel secure the condition before rescue, correction or investigation.
9. Sources and review limits
Public-source access/review: 2026-10-13.
| Official source | Reviewed scope and limits |
|---|---|
| OSHA 1910.333 | Electrical safe work, isolation, verification and controlled reenergization. |
| OSHA 1910.147 | Hazardous-energy controls for covered machine servicing; electrical scope must also be resolved. |
| OSHA 1926.417 | Construction circuit lockout and tagging within scope. |
No actual equipment model, SDS, site measurements, design calculations or authorization record was supplied. Product-specific limits and methods must be verified before use. Federal OSHA is a baseline within its scope; determine the applicable State Plan and local requirements. Manufacturer guidance is not government approval; an incorporated standard differs from voluntary guidance. No nationwide-compliance or expert-approval claim is made.
10. PDF guidance and FAQ
PDF A covers basic task controls; B focuses on technical failures; C covers supervision, records and handover. The article has eight stages with four items per main cell; each PDF has six key stages with three items per main cell. P/S/R/A, measurements, confirmations and signatures remain blank for actual site assessment.
PDFs are complementary six-stage extracts. Apply all eight body stages and the actual equipment/site procedure.
Can a stop button isolate the MCC?
No. Identify and isolate all relevant sources using the applicable procedure and qualified verification.
Can all forced values simply be deleted?
Use the approved restoration sequence, inventory and machine safeguards; an uncontrolled change can initiate motion.
Does a successful manual test release automatic operation?
No. Verify the approved configuration and required remote, protective and automatic states before the designated authority releases operation.
Has a professional verified or approved this document?
No. Public sources and editorial, layout and consistency checks were reviewed using AI. No site inspection or professional technical approval has been performed. Obtain appropriate professional review before use.
11. Revision history and authorship
This is reference content written and revised with AI. It has not been verified or approved by a professional. Review by a suitably qualified professional and site authorization are required before use.
| Date | Version | Change | Review status |
|---|---|---|---|
| 2026-10-13 | US 1.0 | New US edition from assigned Korean source; task decisions, records and PDFs localized. | AI editorial review; no professional technical approval |
Korean edition revision history: 2026-09-19 (v1.1): earlier published draft/version retained in the source history; 2026-09-23 (v1.2): task decisions, record checklist, JSA and three PDF variants revised. These are editorial records, not professional technical approval. US v1.0 adapts the earlier edition to United States requirements and terminology.
Site reviewers must add their actual qualifications, scope, date and approval only after the review occurs.