Friday, February 18, 2011
More on mistake-proofing: lock out what you don’t want to happen
The Epson projector I use for PowerPoint presentations has two VGA connectors on the back. The left (output) one is black and labeled Monitor Out. The right one (input) is blue and labeled Computer (Component Video).
The VGA video output connector on my laptop computer also is blue, and the connecting cable I use is blue and has blue ends. Even so, while in a hurry, I once hooked the video signal from the computer to the black Monitor Out connection on the projector. Then I spent a few anxious minutes puzzling over why nothing was being projected.
Recently I blanked out that connector with a cover of white plastic sheet, since I never meant to use it. Black electrical tape or masking tape also would have worked. The cover was one more form of mistake proofing my outfit.
Covering that unwanted connector also was a crude version of an important safety concept called Lockout /Tagout (LOTO). During maintenance you need to insure that electrical power (and other forms of hazardous energy) are positively shut off, and that others know what is going on so they don’t accidentally turn them back on. Locks are used for shut off, and tags are used for identification.
If more than one person, department, or contractor is working on a piece of equipment, then a hasp with multiple locks will be used. There are standards specified by the government for how to do this. In the US they are OSHA under 29 CFR 1910.147.