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Awareness barriers and chains: when OSHA accepts them as machine guarding

Many shops wonder whether a chain, a railing or a warning sign can stand in for a physical guard. OSHA has answered this in an interpretation letter and in a directive specific to metal-cutting shears.

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Answers are written by a language model solely from this base's documents, with numbered sources. They can be wrong and aren't legal, medical or financial advice: check the sources before any important decision.

Why a chain is generally not a guard

In a May 28, 1996 letter, OSHA explained that machine guarding standards contemplate a physical means of preventing contact with moving parts. An awareness barrier such as a chain depends largely on human behavior, so it would not provide the necessary protection.

The letter notes one exception: where there is no reasonably foreseeable reason for an employee to enter the area. The employer must consider every possible reason for entry, including oiling and cleaning, and foreseeable misconduct such as "sneaking a smoke". The page notes this letter is an archive document that may no longer represent OSHA policy.

The specific case of metal-cutting shears

OSHA Instruction STD 01-12-025 (July 12, 1994) tells compliance officers to accept properly applied awareness barrier safeguarding, as specified by ANSI B11.4-1993, as point-of-operation safeguarding on metal-cutting shears.

This applies only where it is impossible to use a fixed guard or a point-of-operation device because of the diversity of operations on the shear. It is a narrow exception, not a general alternative to guarding.

Frequently asked questions

Does a locked gate remove the need for other guarding?

OSHA said a locked gate that prevents entry into the danger zone would negate the need for additional guarding. It only works if employees can get the key and enter when the moving-part hazards are not present, because the standards do not create a class of "authorized" employees who may be exposed.

What about an interlocked gate on a machine that coasts to a stop?

An interlocked gate is not acceptable if an employee can reach the danger zone before the machine stops. OSHA recommends a time delay so the gate cannot open until moving parts have fully stopped.

Does lockout/tagout also apply when entering a guarded area?

If the purpose of entering is servicing or maintenance, OSHA notes that 1910.147, the control of hazardous energy (lockout/tagout) standard, may apply.

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