Controller Disconnecting Means - LOTO

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whiggins

Member
Location
Kansas
I have an issue on a current design that I'm having trouble understanding the code requirements. I'll set this up as briefly as I can - sometime I'm wordy.

We have four movable vertical lift bridge spans. Each span has a drive motor coupled to machinery at each end to raise the spans. Each drive motor has a local disconnect. Each bridge span has a control cabinet containing two circuit breakers, two motor starters, control relays, and pushbuttons on the cover. There is a 480V feed to each control cabinet from a switchboard. A 120V control power feed is also provided from a panelboard for each control cabinet. The four control cabinets, switchboard, and panelboard are located in an electrical room off the bridge spans.

The panel builder has proposed not using a disconnect at the control cabinets but instead provide markings of where the power feed and control power disconnects are located. Because the switchboard and panelboard are in the same room I believe this is code compliant. If so, do the circuit breakers at the switchboard and panelboard need to be supplied as LOTO breakers?

Another questions is whether each circuit breaker at the control panels feeding a motor starter needs a through the door disconnect. It seems 430.102 (A) would require one. You cannot see the motors from the control room so I would think exception No. 2 does not apply.

I'm looking to see if there is agreement on how I'm looking at this. I know the panel builder is a UL listed shop but they did not bid the through the door disconnects.

I appreciate any insight.

Regards,
whiggins
 

pfalcon

Senior Member
Location
Indiana
Wordy is good in this case.

Much of what you are describing also falls under NFPA79:2007. The 79 is a voluntary standard that can be adopted by your company to fulfill the requirements of OSHA as a nationally recognized consensus standard as an "Electrical Standard for Industrial Machinery". Since this is voluntary you can adopt a different standard or roll your own. 79 fits nicely with ANSI B11, NFPA70, and NFPA70E. I highly recommend it.

Addressing the several issues one at a time:

1) The control cabinets need to be interlocked to their disconnecting means NFPA79:2007:5.3.1.4 except when 6.2.4 and 16.2 have been met. So you can do this but make sure you have all the signage required. Here's a link to the NFPA online.

http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp?cookie_test=1

2) Yes, the disconnecting means requires LOTO. There are others on this forum that can provide better examples than I can. I primarily work with industrial machines, not breaker panels.

3) Wow. There are really two issues here.

3a) Through the door disconnects are not NFPA70E compliant. (instant flame generator). Basic LO process requires the following steps:
>> Turn off disconnect
>> Lockout disconnect
>> Open door
>> Lock must still be integral to the locking mechanism
Most through the door disconnects suffer from one of two failings; Either you have to open the door before locking out or the lock pulls away from the disconnecting means.

3b) 430.102(A) requires a disconnect for the motor controllers to be in sight of the controller. 430.102(B) requires a disconnect for the motor to be in sight of the motor. These are separate requirements. The controller disconnect can also disconnect the motors provided it fulfills all the requirements to be a motor disconnect. Since the controllers are not in sight of the motors, you must have local motor disconnects in addition to the controller disconnects. Just not "through the door" style.
 

whiggins

Member
Location
Kansas
Thank you for your answer. It has helped. The owner has not adopted NFPA 79. After review of your comments and the related sections I believe the following would be code complaint:

1. Provide signage at each control panel indicating what circuit breakers feed the panel and their location. I believe this would comply NFPA 70 Article 409 on industrial control panels. (These would not be LOTO type.)

2. Provide through the door operating handles for the circuit breakers feeding each controller to satisfy 430.102(A).

3. Because the controller disconnecting means is not capable of being locked and not within sight of the motors provide LOTO disconnects at each motor.

Does this sound reasonable?
 

pfalcon

Senior Member
Location
Indiana
Not surprised about the NFPA79 non-adoption. Most companies don't realize the need for it until OSHA pops in. Have the EE at your site contemplate it.

1) We believe this is so.
2) NFPA70E:2009:120.2(E)(1) and OSHA 1910.303(f)(4); required disconnecting means shall be capable of accepting a lock. So that goes back to 2 in my prior post.
3) Yes to the motor lockout disconnects. And see 2 regarding the controller disconnects.
 
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