Safety Switches Requirements

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fjrivera

Member
Greetings,

Can anyone can give me direction where to find in the NEC the requirements for Safety Switches installation?

An auditor told me that safety switch need 36 inches clearance and to be readily accessible. Is this necessary if the safety switches are used only to disconnect for motor maintenance?

In our case the motors disconnective means and motor control are inside buildings in the MCCs.

Thanks.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
This gets debated here and in the field on occassion.
Most arguments end up concetrating on the highlighten passage below:


110.26 Spaces About Electrical Equipment.
(A) Working Space. Working space for equipment operating at 600 volts, nominal, or less to ground and likely to require examination, adjustment, servicing, or maintenance while energized shall comply with the dimensions of 110.26(A)(1), (A)(2), and (A)(3) or as required or permitted elsewhere in this Code.
 

fjrivera

Member
Thanks for the responses. But, what about access to the safety switch? Suppose a motor is located in a wall 10 feet above the floor and the safety switch is installed next to the motor (10 feet also above floor). So is not "accessible". The SS is used only for maintenance purpose and the motor controler is installed inside the Building in a MCC. Is this in violation with the NEC?
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
404.8 addresses the location of switches and allows exceptions for the situation you describe.
 
Thanks for the responses. But, what about access to the safety switch? Suppose a motor is located in a wall 10 feet above the floor and the safety switch is installed next to the motor (10 feet also above floor). So is not "accessible". The SS is used only for maintenance purpose and the motor controler is installed inside the Building in a MCC. Is this in violation with the NEC?

If the motor controller (in the MCC) is located out-of-sight but has a lockable disconnecting means, it is permitted to be the only means of disconnect and no additional local disconect is required. This is an exception in 430.102 for industrial location or where it adds an increased level of hazard.
 

BAHTAH

Senior Member
Location
United States
Disconnect Loaction

Disconnect Loaction

Thanks for the responses. But, what about access to the safety switch? Suppose a motor is located in a wall 10 feet above the floor and the safety switch is installed next to the motor (10 feet also above floor). So is not "accessible". The SS is used only for maintenance purpose and the motor controler is installed inside the Building in a MCC. Is this in violation with the NEC?

240.24(A)(4) Overcurrent devices located next to equipment can be mounted above 6ft 7in., if accessible by portable means. This would mean if you can access the disconnect with a ladder your ok.

404.8(A)Exception No. 2 Switches and circuit breakers used as switches can be mounted above 6ft 7in. if they are next to the equipment they supply, and are accessible by portable means.
 

iwire

Moderator
Staff member
Location
Massachusetts
If the motor controller (in the MCC) is located out-of-sight but has a lockable disconnecting means, it is permitted to be the only means of disconnect and no additional local disconect is required.

IMO that is only true if it is imposable to locate a switch near the motor.

There is a a difference between impractical and impracticable.
 
IMO that is only true if it is imposable to locate a switch near the motor.

There is a a difference between impractical and impracticable.

Say s-l-o-w-l-y I-M-P-O-S-S-I-B-L-E.............:)

Please show me where the wording is in the Code as you claim. I have included the wording in the Code in my post, but you have chosen to cut that off and it has nothing to do with possible or impossible.

Random House unabridged Dictionary lists 'impracticable' as one accepted use of the meaning 'impractical'

  • impractical in the context of the Code means: not practical, not useful
  • impracticable in the context of the Code is: unsuitable for practical use or purpose, as a device or material.
It is interesting to me to see it in the beginning of the 430 to see the pictorial representation of components and it shows the means of disconnect right at front of the controller. Makes sense. Combination starters also m,ake sense. Most equipment, unless it is a package of multi-motor packaged equipment, uses combination staters and a lot of them are located in centralized, MCC units. To add an additional means of disconnect within the sight of the motor does not make much sense to me in the vast majority of the cases I can think of. In many places it increases the hazard potential, it always reduces reliability and increases maintenance cost and it also increases initial investment without any return of benefits. (It is clearly a 'Government' add-on.)
 

iwire

Moderator
Staff member
Location
Massachusetts
impracticable in the context of the Code is: unsuitable for practical use or purpose, as a device or material.


Your mistaken at least as far as the NEC, read the panel statement.


Report on Proposals ? May 2004 NFPA 70

11-64 Log #3272 NEC-P11
(430-102(B) and Exception)

Final Action: Reject

Submitter:
Joseph A. Hertel, Safety and Buildings / Rep. Dept. of Commerce, State of Wisconsin


Recommendation:

Delete current language of 430.102(B) and the Exception, replace with:
430.102(B) Motor. A separate disconnecting means shall be located in sight from the motor location and the driven machinery
location.
Exception: A disconnecting means, in addition to the controller disconnecting means required in accordance with 430.102(A), shall
not be required for the motor where the disconnecting means for the controller is individually capable of being locked in the open
position. The provision for locking or adding a lock to the disconnecting means shall be permanently installed on or at the switch or
circuit breaker used as the disconnecting means.

Substantiation:

The change in the 2002 NEC to this section did not address current practice of a locking disconnect at the controller location. The FPN
implies that it may be impracticable or hazards increased when disconnects are added for submersible motors, and motors located in
hazardous locations among others. The addition of disconnects in hazardous locations can be accomplished with the appropriately
listed equipment. While this is expensive, it does not increase the hazard merely the cost of the installation since the equipment is
clearly evaluated for the use. A well pump is an example of a submersible motor and while it is impracticable to place a disconnect in the
casing so as to be insight less than 50 feet from the motor, it can be placed at the top of the casing. The use of locking disconnects at the
controller for motors has been in the NEC since the 1987 edition. Instead of adding additional requirements to the NEC, it may be more
appropriate to educate users as to why there are locking mechanisms on these already present disconnects.

Panel Meeting Action: Reject
Panel Statement:

The submitter has not provided any technical substantiation to warrant this revision. The proposed new exception is the exception as it
appeared in the 1999 NEC. The Panel reaffirms its position that where practicable and where the installation does not add increased or
additional hazards, the motor disconnecting means shall be located within sight from the motor and driven machinery. The Panel further
reaffirms its position on the effectiveness of lockout/tagout programs that were established during the 2002 Code cycle. The data
reviewed by the panel on the effectiveness of Lockout/Tagout programs shows a correlation between the type of the facility and the
effective implementation of the program. Part (b) of the exception currently provides that for industrial installations, with written safety
procedures, where conditions of maintenance and supervision ensure that only qualified persons service the equipment, the local
disconnecting means is not required. This provision should ensure that only those facilities that are most likely to have an effective
Lockout/Tagout program can utilize the exception.

Number Eligible to Vote: 14
Ballot Results:

Affirmative: 14

1168


 

iwire

Moderator
Staff member
Location
Massachusetts
It appears the rules changed in 99 or 02 so it is very likely you just did not hear about the change.

The panel coulnd not have been......gasp.......WRONG! They are all English majors

I think you may like some of the panel members comments from the 2002 ROP on the same subject. It seems some felt like you do.

EXPLANATION OF NEGATIVE:
COX: “Practicable” is synonymous with “practical”. The style
manual (3.2.1) lists “practical” as a term that is possibly
unenforceable and vague and states that the NEC shall not
contain requirements that are unenforceable and vague. Every
local disconnect installation could be argued as practicable or
impracticable depending on the point of view.
It could also be argued that the addition of a local disconnect
increases the hazards to persons or property for every
installation. The local disconnect adds one more electrical
device into the motor circuit. That device can fail through
abuse, can be wired incorrectly, can fault to ground, can short
circuit and can be operated by unqualified persons. This is the
only location in the electrical system that unqualified persons
can be easily exposed to live circuits, even with the
disconnecting means in the off position


HAMER: When the Lockout/Tagout requirements within the
NFPA 70E and OSHA are followed, additional disconnect
safeguards are not required for personnel safety. This
information is highlighted by the existing FPN. Additional
disconnects add complexity without safety improvement
benefits. The petroleum industry has a record of safe
operation using the current National Electrical Code
requirements in combination with the Lockout/Tagout
requirements of NFPA 70E.

SAUNDERS:
• Insufficient substantiation of a problem relative to the lack
of use of a disconnect in sight of the motor for all applications
was not provided;
• The use of the term “ impracticable” in the exception is not
enforceable. The present text is enforceable and well
understood as it exists;
• The present regulations for lockout (i.e. OSHA 1910.147
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
I think you may like some of the panel members comments from the 2002 ROP on the same subject. It seems some felt like you do.
So did I when I was on the Panel.:grin: (96)

In truth, what is "part b" of 430.102(B)Exception pretty much opens up the industrial usage - and if you read FPN No.1 it's pretty hard to find one of the "impracticable" applications in "part a" that isn't industrial.
 

fjrivera

Member
It was explained to the auditor using 430.102 (with the exceptions) and OSHA CFR. Safety switches are used only to service motors and was an industrial installation. Also, LOTO procedures are up to date , training effective and motor are lockable in MCCs (as per LOTO procedure and accepted by NEC and OSHA).

Case closed and no additional issues and/or observations regarding.
 
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