Although 1910.147 is not intended to prevent contact with live electrical parts, OSHA electrical safety-related work practices standards (1910.333) do address LOTO for protecting against electrical shock. Diligently complying with 1910.147 will also yield that benefit.
The purpose of LOTO is to safeguard employees from unexpected startup of machinery or equipment, or release of stored energy, during the performance of servicing or maintenance. If that task is performed without LOTO, and some parts of the machine could move, there are still not necessarily grounds for a citation. Where will the hands or other body parts be located, or could they easily stray, during the work?
In certain cases, hot tap operations are exempt. This involves transmission and distribution systems for gas, steam, water or petroleum products when the work is done on pressurized pipelines. Also, normal production operations are seldom covered by 1910.147. The standards provide more detail on these matters, as well as when minor servicing tasks are allowed without LOTO.
Many companies designate a lockout/tagout center, a central area for padlocks, special blocking devices and other hardware and tags. Although this is a good starting point, a complete energy control program must be in place. The program must include documented energy control procedures, an employee training program and periodic inspections of the use of the procedures. The foundation of LOTO is the guarantee that all relevant operations will be isolated and rendered inoperable. It is not sufficient to write a general policy. In most cases, LOTO procedures must be machine-specific. (The standards include a section that indicates under what stringent, limited situations, this specificity is not required.)
Employers who fail to document step-by-step procedures for LOTO on a particular machine can face OSHA penalties and, more importantly, substantial risks to employees. There should be detailed, numbered, unambiguous procedures from start to finish for each relevant piece of equipment. In addition to keeping master copies of the procedures (one in the safety department, one in the maintenance department), there should be a laminated copy at the machine. Log exactly what energy sources exist on the machine and who is authorized to perform the LOTO. Include statements about removing all unauthorized persons from the area and assuring that there are no loose parts or other articles in precarious positions.
There must be a fully detailed and ordered list of precisely where (and how, such as by lock) the energy-isolating devices and tags will be applied. Leave no doubt as to which locks, hasps, chains, blocks, etc., may be used. Include descriptions of the following:
In addition to devices being applied, there are times when parts, such as fuses, will need to be removed as well.
The coordination must leave no protection gap; communication should never rely on assumption. One employee should always know where the other(s) are. Similarly, working with outside contractors carries special burdens of teamwork. In all cases, the number of keys that will open a particular lock should be very limited. There are to be no master keys. I recommend that for any individual lock to be used, there be no more than two keys in existence to open it: One key belongs to and is in the constant personal possession of the employee who also controls the paired lock; the other key can be under the total control of the maintenance supervisor, plant manager or person of similar title.
The LOTO standards describe the necessary properties of all devices to be used. This includes durability and standardization of color, shape, size, print and format. Locks and tags must be marked to clearly identify who applied them. The warning message on the tags must be simple, straightforward, and undoubtedly convey the correct information.