Fan Motor Disconnects, Within Sight

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infinity

infinity

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I have a bank of VFD's in a machine room that were relocated and are no longer within sight of the 5 HP and 10 HP fans that they control. Even though the VFD's are lockable are local disconnects (within sight) at the fans still required? This is an institutional building, part of a college.
 
My understanding that the disconnect must be in sight of the motor in all cases. The disconnect for the controller can serve as the disconnect for the mtoor but it still must be in sight. 430.102
 
In my opinion, that type of occupancy always requires a disconnect within sight from the motor, unless the installation meets 430.102(B)(3) Exception part (a). That appears unlikely for this application.
 
Though informational notes are not enforceable code content, the informational notes following 430.102 suggest that motors associated with adjustable speed drives are one possible place where exceptions may apply.
 
I suggest ordering a disconnect with a break first auxiliary contact to kill the VFD before the motor conductors are open. We have a few customers we do this for.
 
kwired said:
Though informational notes are not enforceable code content, the informational notes following 430.102 suggest that motors associated with adjustable speed drives are one possible place where exceptions may apply.
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Good point. I had forgot about the note.

I am not sure the the protection of the VFD should be important enough to permit the elimination of the "in-sight" disconnect, but the note sure suggests that.
 
infinity said:
I have a bank of VFD's in a machine room that were relocated and are no longer within sight of the 5 HP and 10 HP fans that they control. Even though the VFD's are lockable are local disconnects (within sight) at the fans still required? This is an institutional building, part of a college.
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It sound like the exception is JUST for the case you describe:


Exception to (1) and (2): The disconnecting means for the​
motor shall not be required under either condition (a)...


(a) Where such a location of the disconnecting meansfor the motor is impracticable or introduces additional or​
increased hazards to persons or property....

Informational Note No. 1: Some examples of increased oradditional hazards include, but are not limited to, motorsrated in excess of 100 hp, multimotor equipment, submersiblemotors, motors associated with adjustable speed drives,​
and motors located in hazardous (classified) locations.
 
So, since it would be possible to open the remote disconnect adjacent to the motor without shutting down the drive first that local remote disconnect is not required? If the VFD were a standard motor starter then the exception would not apply?
 
iwire said:
Just because it is allowed does not make it a good design.

Any additional hazard that the switch may present can be mitigated.
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Indeed it IS a good design. The requirement of a disconnect to be adjacent to the motor is moronic, antiquated and a bad design. As long as there IS a means of disconnect in the circuit, its location is clearly identified at the equipment to be disconnected, the circuit reliability should not be burdened with the additional disconnect and its failure potential. Not to mention the additional cost.
 
weressl said:
Indeed it IS a good design. The requirement of a disconnect to be adjacent to the motor is moronic, antiquated and a bad design.
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:D

Well we could not be further apart on that. :)

From my perspective this is 2013, not 1970 or 80 and safety is more of an issue than ever. Having a disconnect at the motor in most cases raises the level of safety not lowers it.

As long as there IS a means of disconnect in the circuit, its location is clearly identified at the equipment to be disconnected, the circuit reliability should not be burdened with the additional disconnect and its failure potential.
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Yeah, properly sized and installed non-fused disconnects just fail all the time, why I am changing at least one a day. ;)



Not to mention the additional cost.
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Cost? as a percentage of the job cost it is low unless it is in a hazardous location and in those case a remote disconnect could make sense.
 
weressl said:
Indeed it IS a good design. The requirement of a disconnect to be adjacent to the motor is moronic, antiquated and a bad design. As long as there IS a means of disconnect in the circuit, its location is clearly identified at the equipment to be disconnected, the circuit reliability should not be burdened with the additional disconnect and its failure potential. Not to mention the additional cost.
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I think that is a valid point in some situations and is addressed by exception (b). with a controlled environment, LOTO enforcement and trained personnel, however, a lot of mechanical repairs are performed by poorly trained, semi-illiterate folks who would not likely look up a remote disconnect but who might operate a local disconnect.
The cost of the disconnect is insignificant to the cost of the medical expenses and lawsuit accompanying an accident.
 
augie47 said:
I think that is a valid point in some situations and is addressed by exception (b). with a controlled environment, LOTO enforcement and trained personnel, however, a lot of mechanical repairs are performed by poorly trained, semi-illiterate folks who would not likely look up a remote disconnect but who might operate a local disconnect.
The cost of the disconnect is insignificant to the cost of the medical expenses and lawsuit accompanying an accident.
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Gus you expressed my exact thoughts.:)

In my world people servicing fans have little if any safety training and would be far more likely to use the disco if it is staring them in the face.

Personally I would like the 50' reduced to 25' for in sight.

On the other hand in a place that has hazardous locations there are likely to be better trained or at least you would hope so.
 
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