Alternative methods, minor servicing and exceptions

Lockout is the default, but it is not always practical. An operator who clears a jam from a labelling machine 30 times a shift cannot spend 10 minutes locking it out each time; a technician setting up a robot may need power to the robot to teach it positions; some processes cannot be fully de-energized without creating a greater hazard. Standards in both countries recognize these situations and allow alternatives, but only under strict conditions. This lesson explains the exceptions and alternative methods, and why they must never become a loophole.

Why alternatives exist

There are three common reasons lockout may not fit a task:

• frequency: tasks such as clearing jams, adjusting guides or changing small tools happen so often during production that full lockout every time would stop production and, in practice, would simply be skipped;
• necessity of energy: some tasks, such as troubleshooting, teaching a robot or fine adjustment, need power to some parts of the equipment;
• process constraints: shutting down a continuous process, a furnace or a chemical reaction may create greater hazards than controlling exposure in another way.

The honest answer to these problems is not to tolerate unprotected work, but to design protection that works for the task. That might mean redesigning the machine so the task is not needed, moving the adjustment point outside the guard, or using engineered safeguards that reliably prevent hazardous motion while a person is exposed.

The hierarchy of control for hazardous energy

Both CSA Z460 and ANSI/ASSP Z244.1 apply the hierarchy of controls. In order of preference:

• eliminate the need for the task or the exposure, for example by redesigning the jam-prone part or providing remote adjustment;
• lockout or other energy isolation;
• alternative methods based on a documented risk assessment, using engineering controls such as safety-rated interlocks, trapped key systems and safety-rated monitored stops;
• administrative controls and PPE, which on their own are never adequate protection against hazardous energy.

Alternative methods under CSA Z460

CSA Z460 allows other methods of hazardous energy control when lockout is not practicable, provided a documented risk assessment shows that the alternative gives effective protection for the specific task. The risk assessment identifies the task, the hazards, who is exposed and how often, evaluates the risk, selects controls using the hierarchy, and verifies that the residual risk is acceptable. Workers and the health and safety committee should be involved. The alternative method is then written into a procedure, workers are trained on it, and it is reviewed regularly.

Provincial regulations take a similar line. Quebec's regulation allows a method other than lockout where it ensures equivalent safety and the employer documents it; Alberta, British Columbia and other provinces allow safe work procedures or equivalent protection where lockout is not practicable. In every case, the employer must be able to show why lockout is not practicable and how the alternative protects workers as well.

Examples of alternative methods

Common engineered alternatives include safety-rated interlocked guards with control circuits designed to recognized performance levels, trapped key interlock systems that make it physically impossible to open a guard until power is isolated, two-hand controls for some setup tasks, safety-rated reduced speed with enabling devices for robot teaching under CSA Z434, and safety-rated monitored standstill. Each must be designed to an appropriate level of reliability, assessed under standards such as ISO 13849-1 or IEC 62061, and checked regularly.

Cord-and-plug equipment

Equipment powered only through a cord and plug, with no other energy sources, can be controlled by unplugging it, provided the plug is under the exclusive control of the person doing the work. Exclusive control means the plug is physically in the worker's possession or in sight and within reach, so no one else can plug it back in. If the plug is out of sight, for example behind a machine or in another room, a plug lockout device should be used. Equipment with other energy sources, such as compressed air or stored energy, still needs those controlled.

Hot tapping and live work

Hot tapping is welding a connection onto a pressurized pipeline while it remains in service, used on gas, steam and water lines where shutdown would be impractical or would cause a greater hazard. It is a specialized operation with its own procedures and qualified personnel. Similarly, energized electrical work, when it is justified, falls under electrical safety rules rather than lockout. These are not ways around lockout; they are separate disciplines with their own strict controls.

Guarding against misuse

Alternatives and exceptions are often misused. Signs of misuse include a task described as minor that involves reaching deep into a machine, removing several guards or taking more than a few minutes; reliance on stop buttons or e-stops rather than safety-rated systems; interlocks that are routinely bypassed; and 'alternative methods' that exist only as a sentence in a procedure without a risk assessment. Periodic inspections (lesson 11) should check alternative methods as carefully as lockout procedures, including whether the safeguards still work and whether workers are using them as intended.

Mobile equipment and special cases

Mobile equipment, such as forklifts, loaders and trucks, also needs hazardous energy control during maintenance: removing the key, setting brakes, chocking wheels, lowering or blocking raised attachments, disconnecting batteries and releasing hydraulic pressure. Robots and automated cells use a combination of lockout for maintenance and safety-rated modes for teaching and troubleshooting, under robot safety standards. Programmable controllers and remote access create new risks: a network command could restart equipment, which is why newer standards discuss cybersecurity in energy control.

Documenting an alternative method

A documented alternative method usually includes the task description and how often it is done, the hazards and energy sources involved, the people exposed, the risk estimate before and after controls, the engineered safeguards relied on and their required performance, the step-by-step method workers follow, the training required, how the safeguards are tested and how often, and who approved it and when it will be reviewed. Keeping this information together makes it possible for inspectors, auditors and new employees to understand why lockout is not used for that task and what protects the worker instead.

Workers have an important role in alternative methods. They are often the first to notice that an interlock has become unreliable, that a task now takes longer than the risk assessment assumed, or that a workaround has crept in. Programs should invite workers to report these problems and should review the alternative method promptly when they do.