Red Tag or Shut Something Down: Decision Tree
Why this matters
Deciding equipment is unsafe is only half the job. The other half is making sure it actually stays off after you drive away. A verbal "don't use this" gets ignored by the next person who wants hot water or heat. This tree is about the physical act: which control to operate, how to mark it, and how to keep it from being switched back on before the real repair happens. Whether to take it out of service at all is a separate judgment (see the red-tag-vs-warn-vs-proceed tree); this one starts after you have decided it has to come out.
Start here: kill the active hazard first
Before you think about tags and paperwork, remove the energy that makes it dangerous. If the unit is arcing, leaking fuel, venting flue gas into the space, or holding pressure, de-energize or relieve it now, from a safe point, and verify it is actually dead before you touch it. Stored energy hurts people who assumed "off" meant "safe": a capacitor still charged, a line still pressurized, a spring still loaded. Prove it, do not assume it.
Only once the hazard is neutralized do you decide how to keep it that way.
Pick the isolation method that matches who can undo it
The right method depends on how easy it would be for someone to put the equipment back in service, and how bad it is if they do.
| Method | What it is | Holds against |
|---|---|---|
| Verbal warning only | You tell the customer not to use it | Nothing once you leave; use only for low-stakes items |
| Shut off at the source | Close the valve, open the disconnect, trip the breaker | A casual restart, but anyone can reverse it |
| Red tag | A durable, dated tag stating the hazard and "do not operate" | Honest mistakes; it makes the danger visible and named |
| Lockout / tagout | A physical lock on the energy control plus a tag | Deliberate or absent-minded re-energizing; the lock has to be cut |
Move up the table as the consequence of a wrong restart gets worse. A dryer with a shot door switch might be a shutoff plus a tag. A furnace back-drafting carbon monoxide is a lockout, not a sticky note.
If you shut it off: prove the isolation and mark it
Shutting the control is not the same as isolating the hazard. After you operate the valve, breaker, or disconnect:
- Verify the equipment is truly de-energized or depressurized at the equipment, not just at the panel. Test for dead. Confirm zero pressure at a gauge or bleed point.
- Tag the control you operated so nobody flips it back "to see if it works now."
- Tell the customer what you shut and why, in plain terms, and that it must stay off.
A breaker anyone can reset in ten seconds is not isolation; it is a suggestion.
If you red-tag: make the tag do its job
A red tag is a communication device. It only works if it survives you leaving and answers the next person's questions.
- Write what is wrong, the date, and your name or company on it.
- State do not operate in plain words, not code references a homeowner cannot read.
- Place it where the operator's hand goes - on the switch, the thermostat, the valve handle - not tucked behind the unit.
- Photograph the tagged equipment for your record.
If it is truly dangerous: lock it out and control the restart
Some hazards cannot ride on a tag alone: back-drafting combustion, a live conductor a child can reach, a pool pump with a bonding fault energizing the water, a gas leak you closed at the appliance. Here you physically prevent re-energizing.
- Lock the energy control if it accepts a lock, or pull the fuse and take it with you, or cap and lock the gas.
- Tag the lock with the hazard and your contact.
- Get the customer's acknowledgment in writing that the equipment is out of service and why.
- Route the repair to the right trade or the utility, today if it is life-safety.
Recap
- Neutralize the active hazard and verify dead before anything else.
- Match the method to how easily and how badly a wrong restart could happen.
- Shutoff for casual restarts, red tag to make the danger visible, lockout when a restart could injure.
- Verify isolation at the equipment, mark the control, and put the disclosure in writing.
References
- OSHA lockout/tagout standard (29 CFR 1910.147) for control of hazardous energy
- NFPA 70E on establishing an electrically safe work condition (verify dead)
- Trade-standard practice for red-tagging unsafe fuel-fired and pressure equipment
- See related: Red Tag vs Warn vs Proceed on Unsafe Equipment; When to Disable Unsafe Equipment and How to Communicate It