Motor Disconnect Required?

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Hello all,

I work for an OEM and we are a UL508A shop. We follow UL, NEC, NFPA79 codes. Out of practice, we always put a motor disconnect within sight of the motor. My question is, is there such a rule/code that a motor disconnect is required for such motor disconnect or is the main disconnect (located at the main electrical panel) is enough?

Thanks,
CCP
 

charlie b

Moderator
Staff member
Location
Seattle, WA
Every motor has to have a disconnecting means, and the disconnect has to be within sight of the motor location. Reference NEC 430.102(B). So you can only take credit for the breaker at the main panel as being the disconnecting means if that breaker is within sight of the motor location, and is cabable of being locked open.

That said, I don't think the manufacturer of a motor is required to provide the disconnecting means. It can be furnished and installed by the electrical contractor.
 
Hello all,

I work for an OEM and we are a UL508A shop. We follow UL, NEC, NFPA79 codes. Out of practice, we always put a motor disconnect within sight of the motor. My question is, is there such a rule/code that a motor disconnect is required for such motor disconnect or is the main disconnect (located at the main electrical panel) is enough?

Thanks,
CCP
NEC 2008
IX. Disconnecting Means

430.102 Location.
(A) Controller.
......
Exception No. 2: A single disconnecting means shall be permitted for a group of coordinated controllers that drive several parts of a single machine or piece of apparatus.
.............

(B) Motor.
A disconnecting means shall be provided for a motor in accordance with (B)(1) or (B)(2).

(1) Separate Motor Disconnect.

A disconnecting means for the motor shall be located in sight from the motor location and the driven machinery location.

(2) Controller Disconnect.
.......
The controller disconnecting means required in accordance with 430.102(A) shall be permitted to serve as the disconnecting means for the motor if it is in sight from the motor location and the driven machinery location.

Exception to (1) and (2): The disconnecting means for the motor shall not be required under either condition (a) or condition (b), provided the controller disconnecting means required in accordance with 430.102(A) is individually capable of being locked in the open position. The provision for locking or adding a lock to the controller disconnecting means shall be installed on or at the switch or circuit breaker used as the disconnecting means and shall remain in place with or without the lock installed.

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

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

FPN No. 1: Some examples of increased or additional hazards include, but are not limited to, motors rated in excess of 100 hp, multimotor equipment, submersible motors, motors associated with adjustable speed drives, and motors located in hazardous (classified) locations.

FPN No. 2: For information on lockout/tagout procedures, see NFPA 70E-2004, Standard for Electrical Safety in the Workplace.
Any place that employs workers - so not just industrial - is obligated by OSHA to have a written safety procedure.

So you can have a control panel containing multiple motor controlloers and can have the main disconnect act as the means of motor disconnect and it does not necessarily have to be in sight from the equipment they control. I am certain that manufacturers of such equipment do require that the equipment is to be serviced by qualified people and in the instructions they provide the minimum safety requirements the equipment manufacturer requires.

The NEC misguides the user to the NFPA 70 only, it should also refer to OSHA 1910 Subpart S.​
 
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don_resqcapt19

Moderator
Staff member
Location
Illinois
NEC 2008


Any place that employs workers - so not just industrial - is obligated by OSHA to have a written safety procedure.

So you can have a control panel containing multiple motor controlloers and can have the main disconnect act as the means of motor disconnect and it does not necessarily have to be in sight from the equipment they control. I am certain that manufacturers of such equipment do require that the equipment is to be serviced by qualified people and in the instructions they provide the minimum safety requirements the equipment manufacturer requires.

The NEC misguides the user to the NFPA 70 only, it should also refer to OSHA 1910 Subpart S.​
The fact that other occupancies are required to have written safety procedures does not change the NEC rule...the exception only applies to industrial occupancies. If it is not an industrial occupancy you must have a disconnect within sight of the motor.
 

nakulak

Senior Member
I like the fact that manufacturers of decent equipment are putting disconnects in their controllers more and more. I went out to a hotel to install a jockey pump today, not knowing what to expect or what I had to pick up at the supply house (regardless of the info they faxed I went there first to see if the equip was right voltage etc), and was pleasantly suprised to see a beautiful piece of equip with two vsd pumps, a beautifully made controller with integral disco, breakers, overloads and controls. A lot of package rooftop ac units I've wired lately have had integral discos too, and controls that are ready to hook right up to the fire alarm shunt. I like this trend.
 

pfalcon

Senior Member
Location
Indiana
Hello all,

I work for an OEM and we are a UL508A shop. We follow UL, NEC, NFPA79 codes. Out of practice, we always put a motor disconnect within sight of the motor. My question is, is there such a rule/code that a motor disconnect is required for such motor disconnect or is the main disconnect (located at the main electrical panel) is enough?

Thanks,
CCP
See NFPA79:2007:5.5 Devices for Disconnecting (Isolating) Electrical Equipment

5.5.2 The supply circuit disconnecting device (see Section 5.3) shall be permitted to fulfill this requirement where there is no need for disconnecting individual portions of the electrical circuit.

But you need to read the entire section (5.5) and not just the one clause.

---------------
I just would like to have a logical explanation as to why it is so. (weressl)

As to the requirement from 5.5.5(2) "within sight of the part of the machine": This is so you don't rip someone's arm off in the conveyor when you re-energize and get unexpected motion.
 
I just would like to have a logical explanation as to why it is so. (weressl)

As to the requirement from 5.5.5(2) "within sight of the part of the machine": This is so you don't rip someone's arm off in the conveyor when you re-energize and get unexpected motion.
Read what the original question was and perhaps reply to that.

BTW your reasoning is faulty because the paragraph does not say 'within sight of the moving parts' as the moving part of the machinery COULD be out of sight.
 
I like the fact that manufacturers of decent equipment are putting disconnects in their controllers more and more. I went out to a hotel to install a jockey pump today, not knowing what to expect or what I had to pick up at the supply house (regardless of the info they faxed I went there first to see if the equip was right voltage etc), and was pleasantly suprised to see a beautiful piece of equip with two vsd pumps, a beautifully made controller with integral disco, breakers, overloads and controls. A lot of package rooftop ac units I've wired lately have had integral discos too, and controls that are ready to hook right up to the fire alarm shunt. I like this trend.
It's a case-by-case issue. Certainly in a setting where packaged equipment is concerned or in a non-institutional or small commercial setting I can see the justification for safety.

When it is a duplication of other disconnect ahead of the local one I am against it. As an Owner and Operator I would rather pay the maintenance crew the extra money - which may or may not ever occur - that to install an additional equipment that:
  • cost extra in the initial capital investment
  • provides an additional failure point, therefore reduces reliability and availability
  • cost extra to maintain.
I would rather see the enforcment of proper labeling of each equipment as where its lockable disconnect is located and that all Owners are obligated to have proper and updated documentation and drawings available at all times. I think that would provide a much greater level of safety as the individuals who service the equipment would not have to guess. As electricity and water does not mix, neither does electricity and guessing.
 
Currently all of our equipments have a motor disconnect within sight of the motor. We are being told that if we have a lockable main disconnect at the main electrical panel, we do not need a motor disconnect within sight of the motor and because management said that there is nothing in the NEC or NFPA79 states that we need it. I disagree.

According to 430.102B it said that disconnect means shall be within sight..though there is the exception which states that if the main disconnect is capable of lock in the open position, we do not need the motor disconnect

CCP
 
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wyboy

Senior Member
means of disconnect for motor

means of disconnect for motor

Does a shunt trip qualify as a means of disconnect for a motor if the button for the shunt trip is in site but the shunted breaker is in another room.
 
Currently all of our equipments have a motor disconnect within sight of the motor. We are being told that if we have a lockable main disconnect at the main electrical panel, we do not need a motor disconnect within sight of the motor and because management said that there is nothing in the NEC or NFPA79 states that we need it. I disagree.

According to 430.102B it said that disconnect means shall be within sight..though there is the exception which states that if the main disconnect is capable of lock in the open position, we do not need the motor disconnect

CCP
Read the posted paragraphs in http://forums.mikeholt.com/showthread.php?p=1089082#poststop.

It is unclear in your writing above if you are arguing for or against the validity of the option that you do NOT have to have a disconnect within sight if certain provisions are met.
 
I'm not sure what I'm at so, here goes from the beginning.

According to NEC, a motor disconnect is requires with the following exceptions:

Exception to (1) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b), provided the controller disconnecting means
required in accordance with 430.102(A) is individually capable
of being locked in the open position. The provision
for locking or adding a lock to the controller disconnecting
means shall be installed on or at the switch or circuit
breaker used as the disconnecting means and shall remain
in place with or without the lock installed.
(a) Where such a location of the disconnecting means
for the motor is impracticable or introduces additional or
increased hazards to persons or property
(b) In industrial installations, with written safety procedures,
where conditions of maintenance and supervision
ensure that only qualified persons service the equipment

So, we can take out the motor disconnect if we comply with expection b?
 
I'm not sure what I'm at so, here goes from the beginning.

According to NEC, a motor disconnect is requires with the following exceptions:

Exception to (1) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b), provided the controller disconnecting means
required in accordance with 430.102(A) is individually capable
of being locked in the open position. The provision
for locking or adding a lock to the controller disconnecting
means shall be installed on or at the switch or circuit
breaker used as the disconnecting means and shall remain
in place with or without the lock installed.
(a) Where such a location of the disconnecting means
for the motor is impracticable or introduces additional or
increased hazards to persons or property
(b) In industrial installations, with written safety procedures,
where conditions of maintenance and supervision
ensure that only qualified persons service the equipment

So, we can take out the motor disconnect if we comply with expection b?
Yes and no. You must have A disconnecting means. The disconnecting means - provided that is lockable in the open position - can be located out of sight IF either a.) or b.) applies.
 

pfalcon

Senior Member
Location
Indiana
Read what the original question was and perhaps reply to that.

BTW your reasoning is faulty because the paragraph does not say 'within sight of the moving parts' as the moving part of the machinery COULD be out of sight.
You missed the part where they require compliance to NFPA79. 5.5.5(2) is from NFPA79 and adds the requirement that the moving part of the machine must also be within sight.

NFPA79:2007:5.5.5 Each operating means of the isolation devices in 5.5.4 shall be as follows:
(2) Within sight of the part of the machine requiring disconnection.

So where NEC states the motor the NFPA79 adds the machine section.
 

pfalcon

Senior Member
Location
Indiana
Currently all of our equipments have a motor disconnect within sight of the motor. We are being told that if we have a lockable main disconnect at the main electrical panel, we do not need a motor disconnect within sight of the motor and because management said that there is nothing in the NEC or NFPA79 states that we need it. I disagree.

According to 430.102B it said that disconnect means shall be within sight..though there is the exception which states that if the main disconnect is capable of lock in the open position, we do not need the motor disconnect

CCP
Neither the NEC nor the NFPA79 ban the use of the panel main disconnect from being used. However to use the main panel disconnect it must meet all the requirements the dedicated disconnect must meet. "Within sight" of the motor (NFPA70) and "Within sight of the part of the machine needing the disconnect" (NFPA79).
 

Horton

Member
read closer

read closer

NEC 2008 430.102 (2) exception permits motor installation WITHOUT disconnect AND out of sight of controller if the controller is properly installed AND has capability of locking the motor circuit open with the locking mechanism remaining attached to the controller.
 
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