Motor Control Panel Working Clearance

Status
Not open for further replies.
N

nhee2

Senior Member
Location
NH
I have a 480 VAC panel with starters and VFDs. Because there is the possibility of opening the cabinet (for troubleshooting) while energized, and because there is grounded equipment in front of the panel, I believe I need 42" working clearance in front of the panel, even though the energized / exposed components are in the back of the panel and the panel is 24" deep.

- The code seems pretty clear to me - but am I correct to take the 42" from the front of the panel and not from the internal, exposed components?

- If the power distribution blocks / terminations are covered/made fingersafe through protective shields/other means - are these still considered 'exposed'? I am thinking they are still exposed but looking for other opinions.
 
nhee2 said:
I have a 480 VAC panel with starters and VFDs. Because there is the possibility of opening the cabinet (for troubleshooting) while energized, and because there is grounded equipment in front of the panel, I believe I need 42" working clearance in front of the panel, even though the energized / exposed components are in the back of the panel and the panel is 24" deep.

- The code seems pretty clear to me - but am I correct to take the 42" from the front of the panel and not from the internal, exposed components?

- If the power distribution blocks / terminations are covered/made fingersafe through protective shields/other means - are these still considered 'exposed'? I am thinking they are still exposed but looking for other opinions.
Click to expand...

It says "Distances shall be measured from the exposed live parts or from the enclosure or opening if the live parts are enclosed.", so yes from the front of the enclosure applies.

terminal shields may still need to be removed to take measurements, even if there is small access holes to insert probes - you still have risk of electric shock and/or arc flash hazards present.
 
Thanks for the replies - confirming my interpretation. Unfortunately this will result in some rework to an installation that was already in progress prior to my feedback to the design. Was making sure there was not an exception or provision that I was overlooking.
 
Status
Not open for further replies.
Top