Machine main disconnect location

Jsantangelo

Member
Location
Columbus,Ohio
I have a question concerning the location of the main control enclosure and main disconnect of a machine I am currently working on. My customer would like me to put the main enclosure and disconnect of their new equipment in a separate room from the equipment. The equipment we are building is has a 6 axis robot with a max payload of 700kg. I have been reading the NFPA 79 and am getting confused as to location of disconnect means if line of sight is required. My customer has stated that they intend to put a window in the room (This window does not currently exist) in order to view the robot and the rest of the equipment from inside the other room. Does this meet line of site? Also, my main disconnect will be lockable when in the open position?

Any help would be appreciated.

Joe
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
I have a question concerning the location of the main control enclosure and main disconnect of a machine I am currently working on. My customer would like me to put the main enclosure and disconnect of their new equipment in a separate room from the equipment. The equipment we are building is has a 6 axis robot with a max payload of 700kg. I have been reading the NFPA 79 and am getting confused as to location of disconnect means if line of sight is required. My customer has stated that they intend to put a window in the room (This window does not currently exist) in order to view the robot and the rest of the equipment from inside the other room. Does this meet line of site? Also, my main disconnect will be lockable when in the open position?

Any help would be appreciated.

Joe
NFPA 79 would apply to the machine control panel itself. The "line of site" rules they discuss are that you must have the disconnect in or on the main control panel so that all circuit elements are dead if the door is opened, or in direct line of site with certain precautions taken. If you have the entire control system in the other room, thats OK per NFPA 79, but if some control systems tied to it are on the machines themselves, those would either have to be interlocked in such a way as to prevent entry unless the main power was cut off. I'm not sure if line of sight to the main disconnect is OK for those, I don't have my copy with me.

There are other rules about line of sight for machine disconnects that fall under NFPA 70 (the NEC) and OSHA. There are reasonable exceptions for industrial facilities with an organized and monitored safety procedure program, I suggest you research them thoroughly. Generally they allow for remote disconnects if there is an established and reviewed LO/TO procedure and adequate signage, all clearly defined in the exceptions and rules.
 

GoldDigger

Moderator
Staff member
I have been reading the NFPA 79 and am getting confused as to location of disconnect means if line of sight is required. My customer has stated that they intend to put a window in the room (This window does not currently exist) in order to view the robot and the rest of the equipment from inside the other room.
If the window does not have a shutter, blind or curtain that has to be opened to allow viewing and if the disconnect itself, not just the general interior of the room. can be seen from everywhere around the machine, I would say the line of sight condition is met.
 
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