A safe first decision is often not a repair. It is a documented boundary: isolate the unit, prevent reconnection, observe only what can be seen without defeating a protective cover, record evidence, and send the equipment to the appropriate qualified path.
De-energized inspection is a boundary, not a generic procedure
Disconnecting a cord removes an external supply; it does not by itself establish a verified zero-energy state. Equipment can contain stored electrical energy, damaged insulation, heat, sharp edges, contamination, moving parts, or an unexpected secondary source. A timer, switch position, indicator lamp, or lack of fan noise is not universal proof.
For a workplace, hazardous-energy control requires an equipment-specific program, assigned roles, communication, isolation, control of stored energy, and verification. For a home or small site, the safest generic scope is narrower: shut down as documented, disconnect the external supply by handling the plug rather than the cord, prevent another person from reconnecting it, keep protective enclosures closed, and escalate when the task would expose an electrical part.
| Activity | Safe boundary in this guide | Stop condition |
|---|---|---|
| External observation | Record labels, approval marks, enclosure damage, cord condition, odour, soot, corrosion, liquid exposure, and connector discoloration without removing a protective cover. | Exposed conductor, melted enclosure, shock event, smoke, fire, liquid ingress, severe contamination, missing approval mark, or uncertain equipment identity. |
| Cleaning or routine maintenance | Use only the exact model instructions and the limits in the preventive-maintenance safety checklist. | The task requires opening a PSU, defeating a guard, disturbing wiring, using a meter, applying heat, or energizing an incomplete unit. |
| Symptom triage | Record external symptoms and follow the safe symptom-led triage guide. | The symptom suggests an electrical, thermal, fire, water, approval, firmware-provenance, or component-level fault. |
| Electronics handling | Only a manufacturer-authorized, de-energized module-handling task under a documented ESD-control plan. | Unknown ground, uncertain isolation, PSU involvement, exposed power path, damaged board, or no trained and authorized owner for the task. |
| Repair and return to service | No generic repair or power-on procedure is provided here. | Any board-level rework, live diagnosis, stored-energy work, improvised energization, approval-impacting modification, or need to certify safe operation. |
A stop-first decision tree
- Is there an immediate hazard? If there is smoke, flame, arcing, a shock report, abnormal heat, liquid exposure, a damaged supply cord, or an exposed conductor, do not touch or reconnect the unit. Keep people away and use the site emergency, fire, electrical, and qualified-service process.
- Can the unit be identified exactly? Record the model, hardware revision, serial number, PSU identity, approval labels, and the exact manual revision. If any identity is uncertain or mismatched, quarantine it.
- Is the task expressly authorized? Confirm the owner, warranty and service boundary, workplace authorization if applicable, and who is qualified to release the equipment. If the task is inferred from a forum, video, or generic article, stop.
- Can the task remain external and disconnected? Shut down using the documented control, disconnect the external source, prevent reconnection, and let the unit reach a stable temperature. Do not infer zero energy inside a PSU or exposed assembly.
- Can evidence be collected without defeating protection? Photograph external condition and record observations without removing a PSU cover, touching a conductor, or introducing a tool into an electrical area. If not, stop.
- Who owns the next decision? Route cleaning and maintenance only to the documented safe scope. Route electrical, stored-energy, approval, or component-level questions to the authorized qualified service path. Do not perform a trial energization to obtain more evidence.
External inspection: evidence, not diagnosis
| Observe externally | Record | Do not infer |
|---|---|---|
| Identification and approval labels | Exact text, serial, revision, supply rating, certification or field-evaluation mark, and any mismatch. | That a label proves the present installation, modification, cord, or internal condition remains compliant. |
| Enclosure and fasteners | Missing or loose parts, deformation, impact, missing guards, broken seals, and signs of prior opening. | That tightening, opening, or substituting hardware is authorized. |
| Cord, plug, and accessible connectors | Cut, abrasion, discoloration, melting, corrosion, looseness, odour, or exposed material. | That tape, cleaning, reseating, or a replacement of unknown rating makes the unit safe. |
| Environmental exposure | Water, condensation, conductive dust, soot, pests, chemicals, salt, extreme heat, or freezing history. | That drying time, appearance, or a normal boot screen clears contamination or insulation risk. |
| Operating history | Last known normal state, alarms, shutdown event, protection trip, smell, sound, temperature, and responsible witness. | That a dashboard value proves electrical integrity or authorizes a test run. |
ESD controls apply only after the electrical boundary is safe
Electrostatic discharge can damage sensitive electronics immediately or create a latent defect. An ESD-control plan defines the protected area, ground system, verified equipment, packaging, handling, inspection, training, and records. A wrist strap and mat are not universal accessories and do not establish de-energization.
- Never attach yourself to ground while an energized or uncertain electrical hazard is present.
- Use an ESD protected area only for an exact, authorized, de-energized electronics-handling task.
- Verify the ESD ground, mat, strap, tester, packaging, and training under the applicable local plan; do not improvise a connection to a chassis, receptacle, pipe, or unknown ground.
- Handle an authorized removable module by its permitted edges, avoid contacts and components, and use suitable protective packaging.
- Stop if contamination, liquid, physical damage, missing protection, or an unknown power path changes the task.
Evidence and measurement worksheet
This record is deliberately non-procedural. It helps the owner and qualified service provider decide what evidence exists, what is missing, and who owns the next step.
| Field | Evidence to record | Gate |
|---|---|---|
| Ownership and authority | Owner, site, work-order reference, warranty or lease boundary, authorized person, and escalation contact. | No authority: quarantine and stop. |
| Exact equipment identity | Miner, PSU, control board, hardware revision, serials, nameplate ratings, approval marks, and photographs. | Mismatch or unknown identity: stop. |
| Controlling documents | Exact manufacturer manual and revision, service bulletin, site procedure, jurisdiction, and reviewer date. | No task-specific document: no opening or service. |
| Hazard history | Shock, trip, smoke, fire, heat, noise, smell, water, impact, contamination, prior modification, and witness. | Any serious or uncertain event: isolate and escalate. |
| Energy control | External shutdown and isolation record, reconnection control, stored-energy owner, and qualified verification record where required. | A timer or switch position alone is insufficient. |
| External condition | Enclosure, cord, plug, accessible connectors, guards, fasteners, labels, soot, corrosion, and liquid evidence. | Damage or missing protection: do not energize. |
| ESD plan | Authorized task, protected area, verified ground and equipment, packaging, trained handler, and test record. | No documented ESD plan: do not handle a module. |
| Decision and owner | Keep quarantined, manufacturer path, qualified electrical assessment, authorized service, replacement, or documented release. | No named decision owner: remain disconnected. |
Return to service is a separate controlled decision
A disconnected visual check cannot certify electrical safety, component integrity, insulation, protective devices, firmware provenance, cooling performance, or compliance. Return to service requires the exact authorized procedure, complete reassembly, restored guards and protective functions, correct approved supply and installation, resolution of recorded damage, and sign-off by the responsible qualified person. This page intentionally provides no power-on test sequence.
Primary sources and review record
Sources and links reviewed 30 August 2026. Requirements vary by jurisdiction, workplace, equipment, and task. Recheck the controlling law, current manufacturer documentation, approval conditions, and local procedures before acting.
- Canadian Centre for Occupational Health and Safety: Electrical Safety – Basic Information, including Canadian jurisdiction, code, shock, burn, fire, and hazardous-energy boundaries.
- CCOHS: Hazardous Energy Control Programs, including unintended start-up, stored energy, and the preference for a zero-energy state where feasible.
- CCOHS: Lockout/Tag out, including equipment-specific procedures, assigned roles, isolation, stored-energy control, and verification.
- NASA Safety and Mission Assurance: Workmanship and ESD control, describing site-specific ESD-control plans, training, and latent electronics damage.
- Ontario: Lockout procedures for equipment maintenance, updated 31 March 2026, illustrating documented isolation, verification, and controlled return to service in one provincial workplace context.
Frequently asked questions
Can I open a miner power supply after unplugging it?
No. This guide does not authorize opening or servicing a power-supply enclosure. Stored electrical energy can remain after external power is removed. PSU inspection, verification, discharge, diagnosis, and repair belong to an authorized qualified service process using the exact manufacturer procedure and applicable workplace controls.
Can I discharge a capacitor before inspecting the miner?
Do not deliberately discharge a capacitor from this article or an improvised method. Capacitor handling is component- and procedure-specific and can create shock, arc, burn, fire, and equipment-damage hazards. Isolate the unit and refer it to an authorized qualified service provider.
Does waiting after unplugging prove that a miner is de-energized?
No. A waiting period is not proof of zero energy. Stored-energy controls and verification depend on the exact equipment, manufacturer instructions, site procedure, task, and qualified person. If those are unavailable, keep the equipment closed, disconnected, and quarantined.
Can I probe a hashboard while it is running?
No. This guide prohibits energized probing and live measurements. It also prohibits exposed-board energization, improvised adapters, incomplete assemblies, bypassed protections, and ad hoc bench-power arrangements. Those activities require a separate qualified and authorized work process outside this guide.
When is an ESD wrist strap appropriate?
Only within a documented ESD-control plan after the equipment is isolated and the task is confirmed to be de-energized and manufacturer-authorized. A grounding strap is not electrical-shock PPE and can create a current path if an electrical hazard remains. Stop if the ground point, equipment state, or procedure is uncertain.
What can a non-specialist inspect safely?
From a stable, dry, disconnected unit, a non-specialist can record external labels, approval marks, enclosure condition, odour, soot, corrosion, liquid exposure, damaged cords, and connector discoloration without removing protective covers. Do not touch exposed conductors or turn visual observations into a repair instruction.
When can equipment return to service?
Only after the exact authorized procedure is complete, required covers and protections are restored, damage has been resolved, approval and installation conditions remain satisfied, and the responsible qualified person has documented release. This article does not supply that release or a power-on test procedure.
Does this guide replace an electrician, technician, manual, or legal requirement?
No. The exact equipment documentation, electrical approval conditions, employer procedures, and federal, provincial, territorial, and local requirements control. Qualifications and permitted work vary by jurisdiction and workplace. When in doubt, stop and use the authorized service path.
