Electrical Isolation Precautions.

[TVH]

Is testing of the isolated circuit with a meter required after isolating the circuit (to verify zero energy state)? Co workers at my location are saying that, after isolation, the local switch only needs to be activated to ensure the equipment does not start.

Info appreciated.

 

[WorkSafe]

If you are going to be working on exposed potentially energized conductors, then you must verify with meter. If you are just going to be working on the equipment, other than exposed conductors, then you can just attempt to start the equipment to verify energy state.

Here is a fairly good OSHA interpretation on the issue:

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=23483

 

[petersonra]

If you are going to be working on exposed potentially energized conductors, then you must verify with meter. If you are just going to be working on the equipment, other than exposed conductors, then you can just attempt to start the equipment to verify energy state.

Here is a fairly good OSHA interpretation on the issue:

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=23483

That part is pretty clear.

The thing I have seen that I do not trust is the people who rely on trying to start a motor by the normal means after a lockout as a means of verifying the lockout is working correctly. I just do not buy into that. But it is a common practice.

 

[fmtjfw]

typical lockout/tagout

typical lockout/tagout

1. de-energize and disconnect power supply(ies)
2. lockout/tagout disconnect(s)
3. attempt to operate device [push start button for instance]
4. verify voltmeter with know energized source
5. using the voltmeter check locked-out circuit for no voltage
6. verify voltmeter with know energized source
lock-out is now "in effect"

Step 5 may require PPE because the circuit is still considered energized at this point.

 

[WorkSafe]

The confusion begins when you are dealing with two seperate standards. Electrical repair is OSHA 1910.333, and mechanical equipment type repair is OSHA 1910.147 (control of hazardous energy).

One deals with getting zapped, the other deals with getting crushed and the like.

 

[zog]

1. de-energize and disconnect power supply(ies)
2. lockout/tagout disconnect(s)
3. attempt to operate device [push start button for instance]
4. verify voltmeter with know energized source
5. using the voltmeter check locked-out circuit for no voltage
6. verify voltmeter with know energized source
lock-out is now "in effect"

Step 5 may require PPE because the circuit is still considered energized at this point.

7. Apply personel protective grounds (if required)

 

[fmtjfw]

7. Apply personel protective grounds (if required)

OK, I admit it, I copied from 70E. You are right about 7. 7 is typically medium voltage and above.