Machinery Safety: the technic to do maintenance works safely

Last edit: 03/03/2023

Lockout-Tagout or LO.TO is a safety procedure for both machinery and process to ensure a safe maintenance. The concept is easy: in order to work safely i should de-energize all the possible energies. To do this it is not enough to open a disconnecting device o close a valve because someone could accidentaly give energy to the machinery or the process. In order to be sure to work in safe condition i have to put my padlock on the disconnecing device.

In the electrical field, it is common to speak about LO.TO.TO., Lockout-Tagout-Testout, because after the disconnecting the operator shall verify that the live parts are no longer energized.

In Europe, the reference Standard is 

EN 50110: Esercizio degli impianti elettrici. Parte 1: Prescrizioni generali. Parte 2: Allegati nazionali

While, the italian Standard is

CEI 11-27: Lavori su impianti elettrici.

In this one, it speaks about work out of tension §6.2 requires

– to disconnect the power supply

– shall be provided means to prevent unauthorized closing of the disconnecting device

Means to prevent unauthorized closing of the disconnecting device are:

1. mechanical locks with key device which does not allow to move the disconnecting device

2. impediments to anauthorized personnel

3. monitoring of the disconnecting device to prevent undue maneuvering


These measures shall be always attuated with appropriate signs which prohibit the execution of maneuvers. 

The Standard does not speak clearly about padlock on the disconnectig device. I shall close the room and ask to a collegue to monitor the area. 

Although, it is not a regulatory prescription, different companies ask us to organize them this procedure. 

GT Engineering could help you with training and consulting to introduce LOTO in your company. It is far less difficult than what you think. Call us to have a chat.