Motor disconnects rule

Status
Not open for further replies.

embryo3

Member
Location
coral springs
I have been asked to hook up about 21 motors on a conveyor system that has a main MCP with VFD's.

the motors are individual on a raised platform (6' aff) and remote about 20 to 50' but not in sight of the main disconnect panel. Are service disconnects required for each of the individual motors under article 430

there are a few exceptions that may apply; it is an industrial area but with personnel that remove boxes from the conveyor so not just accessible by maintenance personnel. Also not sure that this qualifies as a single apparatus?

any input would be greatly appreciated
 

iwire

Moderator
Staff member
Location
Massachusetts
430.102(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.] 02(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 (J) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b), which follow, provided that the controller
disconnecting means required in 430.102(A) is lockable in
accordance with 110.25.

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

Informational Note: Some examples of increased or additional
hazards include, but are not limited to, motors rated
in excess of 100 hp, multi motor equipment, submersible
motors, motors associated with adjustable speed drives, and
motors located in hazardous (classified) locations.


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

Informational Note: For information on lockout/tagout
procedures, see NFPA 70E-20 12, Standard for Electrical
Safety in the Workplace.

You might be able to use exception b.

That said I think it is better practice to provide a disconnecting means at the motor even if that means early break auxiliary contacts have to be installed to shut down the drive before the switch opens and if needed signal a PLC to stop other processes.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Around here, all of the industrials use the exception. The lockout point is the MCC bucket. The only time they use a local lockout is for equipment that is locked out often for routine cleaning or other such activities. Then they will use a local lockout point to save time.
 

iwire

Moderator
Staff member
Location
Massachusetts
Around here, all of the industrials use the exception. The lockout point is the MCC bucket. The only time they use a local lockout is for equipment that is locked out often for routine cleaning or other such activities. Then they will use a local lockout point to save time.

So basically if an operator might have to do daily PMs there is a local disconnect but something like a conveyor motor 20' up that only gets worked on when broken would be at the MCC?

If so I can see that working in places with active safety programs.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
430.102(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.] 02(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 (J) and (2): The disconnecting means for the
motor shall not be required under either condition (a) or
condition (b), which follow, provided that the controller
disconnecting means required in 430.102(A) is lockable in
accordance with 110.25.

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

Informational Note: Some examples of increased or additional
hazards include, but are not limited to, motors rated
in excess of 100 hp, multi motor equipment, submersible
motors, motors associated with adjustable speed drives, and
motors located in hazardous (classified) locations.


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

Informational Note: For information on lockout/tagout
procedures, see NFPA 70E-20 12, Standard for Electrical
Safety in the Workplace.
You might be able to use exception b.

That said I think it is better practice to provide a disconnecting means at the motor even if that means early break auxiliary contacts have to be installed to shut down the drive before the switch opens and if needed signal a PLC to stop other processes.


IMO (a) can also be applied in concert with the informational note regarding VFD's and hazards to them.
 

iwire

Moderator
Staff member
Location
Massachusetts
IMO (a) can also be applied in concert with the informational note regarding VFD's and hazards to them.

Any hazard the VFD itself brings into it can be easily avoided with an extra contact.

That is how I see it done around here. Mostly I see this with air handling equipment disconnect but we have one customer that was a refinery that required us to provide aux contacts in every local disconnect.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Any hazard the VFD itself brings into it can be easily avoided with an extra contact.

That is how I see it done around here. Mostly I see this with air handling equipment disconnect but we have one customer that was a refinery that required us to provide aux contacts in every local disconnect.
I can see that being needed for overall process control integrity and safety in a place like that.
Dropping out one component can affect the entire process line, and relying on proper procedure is an unnecessary risk.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Any hazard the VFD itself brings into it can be easily avoided with an extra contact.

That is how I see it done around here. Mostly I see this with air handling equipment disconnect but we have one customer that was a refinery that required us to provide aux contacts in every local disconnect.

I agree that can be done but does the NEC require it to be done? If opening a remote disconnect damages the VFD then you have complied with (a) if you eliminate the hazard, which is the disconnect.

Personally I dislike most instances where the NEC allows you to eliminate the disconnect within sight. Just because I can put a pad lock on a switch in a distant location doesn't mean that I will do so when servicing the motor or equipment.

I like the idea of the aux contacts in the disconnect, IMO this should be a requirement to force the within sight disconnect.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
So basically if an operator might have to do daily PMs there is a local disconnect but something like a conveyor motor 20' up that only gets worked on when broken would be at the MCC?

If so I can see that working in places with active safety programs.
Exactly and at the plant I often work at, I would bet way less than 5% of the motors have local disconnects.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...
Personally I dislike most instances where the NEC allows you to eliminate the disconnect within sight. Just because I can put a pad lock on a switch in a distant location doesn't mean that I will do so when servicing the motor or equipment.
...
You could do the same thing with a local disconnect. This goes to the safety culture a the facility. In the plants I work in there are sever repercussions for working on equipment that is not locked out, if you get caught. A contractors employee would be escorted off site, and probably not permitted to return for a year. A plant employee would get time off without pay.

Also, most of the equipment, in he plants I work are, is process related, so only the "process owner" can turn the equipment off and place a lock. The process owner is plant employee, with the exception of newly installed equipment that has not yet been placed into service, for that new equipment the electrical contractor is the "process owner".

That being said, I would love to see a "Meltric" type connection on every motor.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Correct me if I'm wrong, but I think there is an often overlooked "catch" here.
430.102(B) (2) states the cotroller disconnect required in 430.102(A) shall be permitted to serve as disconnecting means for the motor if it's in sight from the motor.
The exception (b) states that the disconnecting means shall not be required, with written LOTO, provided the controller disconnect means in 430.102(A) is individually capable of being locked.....
If a control cabinet has a single disconnect for a group of motors if does not seem that would suffice.
If one wishes to say that Exception 2 to 430.102(A) allows the single disconnecting means to suffice (which IMO is questionable), then the the wording of the Exception 2 requires the disconnect means to be insight from the machine or apparatus.

I think all to often we allow a group of motors such as in the OPs post to be allowed to omit disconnects based on a LOTO procedure where the motors are not in sight from the controller disconnect.
 

electricalist

Senior Member
Location
dallas tx
How about in a carwash tunnel?
There are 10 blower/dryer motors, the disconnects were put in site, nema 4 x ,but the constant water has shown the handles will leak.
There is a MCC with a lock out off capability. The customer wants them moved or removed.
Out of 10 disc. 6 have been replaced.
Any sugg.
 

Aleman

Senior Member
Location
Southern Ca, USA
It can be debated and the rules can be interpreted differently depending on who's reading them. But the right way to do
a system as described is to have local disconnects on all motors. Makes it both easier and safer to work on. I don't believe
any inspector would fail to approve of it. In house safety guys also love it. Mechanics like it. More work for the electricians
building it but easier to deal with afterwards.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
How about in a carwash tunnel?
There are 10 blower/dryer motors, the disconnects were put in site, nema 4 x ,but the constant water has shown the handles will leak.
There is a MCC with a lock out off capability. The customer wants them moved or removed.
Out of 10 disc. 6 have been replaced.
Any sugg.
Can you shield the handle area from direct (or bounce) water spray under pressure? Hinged for access?
That plus drain fittings may be enough.
 

Aleman

Senior Member
Location
Southern Ca, USA
How about in a carwash tunnel?
There are 10 blower/dryer motors, the disconnects were put in site, nema 4 x ,but the constant water has shown the handles will leak.
There is a MCC with a lock out off capability. The customer wants them moved or removed.
Out of 10 disc. 6 have been replaced.
Any sugg.

What make of disconnects are they using? We have good luck with the Eaton's that we use. Maybe some kind of shield to keep direct
spray off the discos. Maybe there's a better place to install them?

Here's an Eaton P/N. These are good. I didn't realize how much we paid for these until just now.ER53040UX
 

electricalist

Senior Member
Location
dallas tx
e9cf324c73e8faecb364a8fe15ac3eb8.jpg

Yes sir
 
Status
Not open for further replies.
Top