Multiple disconnects: does it matter where a motor is locked out?

[vasectomy7]

[I'm just an apprentice so I apologize in advance if I sound like an idiot]

I work as an in-house electrician at an industrial facility; I have been told several times by the senior electrician that whenever a lockout-tagout is done, we are required to use the M.C.C. bucket for that purpose. He says it is never acceptable to just lockout at the "local disconnect," right at the particular motor / machine. Is that an official rule in the NEC or 70e?

The most I can find is

NFPA 70e Article 120.4 (B) (11) (1) "Lockout shall be defined as installing a lockout device on all sources of hazardous energy such that operating of the disconnecting means is prohibited. The tagout device shall be installed in the same position available for the lockout device"

Scenario: The drive chain on a screw conveyor has come loose, it needs to be inspected and retightened. Before starting work, which disconnect should be locked?

This is the circuit:
GRID POWER ----> Main 4160v transformer with disconnect ------> 480v M.C.C. bucket with disconnect -----> PLC contactor with manually tripable overload -----> Local disconnect, 10' from the motor -----> Motor

 

[Dennis Alwon]

If you are working on the motor I don't see why the "local" disconnect wouldn't be enough to be locked. In fact, I would want the disconnect that is within sight of where I am working.

Now if the local disconnect is not within sight of where you are working it may be wise to add another lockout at the source but I don't know if that is required.... It may be an inhouse rule

 

[don_resqcapt19]

I could simply be what their lockout procedure requires. Both the local disconnect and the lockable MCC disconnect meet the OSHA and 70E requirements, but you are required to follow the lockout procedure that has been developed for that facility.

 

[tom baker]

If your SOP is the MCC, then use that location, esp if there are multiple trades that’s is where they would expect the group lockout box.

 

[ptonsparky]

The local disconnect may not have feedback to the PLC indicating that it is off. In that case the MCC bucket would be better for maintenance purposes. Other wise, whatever the boss says. Both certainly won't hurt a thing.

 

[Jraef]

I believe somewhere there is wording to the effect of "in an industrial setting under engineering supervision with an established safety program...", it's allowable for the LO/TO to not be within sight of the machine.

Yep, 430.102.B.b

(b) In industrial installations, with written safety procedures,
where conditions of maintenance and supervision
ensure that only qualified persons service the equipment

 

[petersonra]

They might have made that rule up so that you always also disconnect the motor controller. I don't think it's actually required other than the fact that they made the rule up.

 

[TVH]

LOTO always best at the MCC. Follow established precautions of the facility owner. Suggest you take advantage of the "ASK OSHA" web site where OSHA will answer your question(s). Safety First.

 

[GeorgeB]

In my world, electrohydraulics, we want to take things to a "zero stored energy" and "zero input energy" state. The stored means potential energy is 0, loads lowered against a stop. Input energy means we verify visual breaks, either pulled fuses or open blades in a disconnect. Handles down on a MCC bucket doesn't make us happy unless we've seen voltage measurements in and out or the door opened and blades seen, a rare situation where we are often joining others who accomplished the 1st lock installation. If there is a local disconnect, I witness it open and apply my lock. If there is not, I put 3 fuses in my tool pouch and my lock on the door with the fuseholder.

IF I'm first and witness the MCC blades open from outside the boundary, my lock there suffices. We don't normally carry electrical protection gear for service work. RARELY do we need it during installation. The electrical energy is converted to mechanical energy for our work by electricians.