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#84046 - 03/05/03 01:09 PM Work space in front of switch gear  
Tophat  Offline
Junior Member
Joined: Mar 2003
Posts: 3
Temecula, CA.
Per section 110-34 of the 96 NEC, working space distances shall be measured from the live parts if such are exposed, or from the enclosure front or opening if such are enclosed.
So my question is this measurement taken from the outside of the switchgear cabinet or from the dead front inside the cabinet?


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#84047 - 03/05/03 06:44 PM Re: Work space in front of switch gear  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,803
Brick, NJ USA
Tophat:
Welcome to ECN firstoff.

We/I always measure from the front of the enclosure. If it has doors, the door must swing open a full 90 degrees minimum. I mention this, as I have come upon a few installs where there is 3'6" of clearance, but you cannot open the door, as it is 48".

There are special circumstances where a lesser clearance has been allowed, by special permission on a few retrofit installs, where space was a physical imposibility.
John

[This message has been edited by HotLine1 (edited 03-05-2003).]


John

#84048 - 03/05/03 07:02 PM Re: Work space in front of switch gear  
Tophat  Offline
Junior Member
Joined: Mar 2003
Posts: 3
Temecula, CA.
Thanks John, this is a great site for learning.
110-34 says to measure from the enclosure front or opening if such are enclosed. That would mean you would open up the door (opening) and measure from the dead front right?


#84049 - 03/05/03 08:33 PM Re: Work space in front of switch gear  
Nick  Offline
Member
Joined: Aug 2001
Posts: 599
Riverside, CA
Tophat,
I don’t read it that way. The enclosure front is just that. The front of the enclosure the live parts are in. The opening is the door. If you were measuring from the dead front you could be in violation of 110.26(A)(2) and 110.26(E). (2002 references) For example: If you have a 20” wide panel mounted 6’ to the top and you were measuring to the dead front that was set back 8” (just for illustration) from the front of the enclosure, the 8” space inside the panel would not have the required 30” wide space and 6’6” head room. Splitting hairs I know but technically it is a violation. Save your self some trouble and measure from the outside of your enclosures.


#84050 - 03/07/03 02:26 AM Re: Work space in front of switch gear  
elecbob  Offline
Member
Joined: Aug 2002
Posts: 141
WA
The local utility asks for 3 feet clear from the face of installed meters. Figure that one out.
bob


#84051 - 03/07/03 07:03 AM Re: Work space in front of switch gear  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
Please note that 110.34 covers equipment OVER 600 VOLTS.

The answers given here are related to 110.26 for UNDER 600 VOLTS?


Joe Tedesco, NEC Consultant

#84052 - 03/07/03 08:21 PM Re: Work space in front of switch gear  
Nick  Offline
Member
Joined: Aug 2001
Posts: 599
Riverside, CA
Good catch Joe. But in this case the answers don’t change when over 600V. The clearances just get larger.


#84053 - 03/08/03 12:30 AM Re: Work space in front of switch gear  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Compared to many code requirements, this has evolved from grisly burns and loss of life. IMO, this is one requirement where the most-conservative interpretation deserves to be firmly enforced.

[Offhand, in the 1953 NEC, the §110-26 {then §1112} >150V condition 2 dimension was 4 feet.]

An example of non-enforcement was a facility where the “institutional” buildings, {that housed almost all the engineers and inspectors} the >150V condition 1 dimension was 36 inches for 480V panelboards where gypsum wallboard was installed opposite panelboards, but neglected in the “shops” side that had almost all concrete walls; id est, condition 2, where 42-inch clearance was needed for opposite walls being almost exclusively a grounded surface.




[This message has been edited by Bjarney (edited 03-07-2003).]


#84054 - 03/08/03 10:27 AM Re: Work space in front of switch gear  
Len_B  Offline
Member
Joined: Jan 2003
Posts: 53
New Hampshire
I believe HotLine1 and Nick and have the proper interpretation.

[This message has been edited by Len_B (edited 03-08-2003).]



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