Minimum MCC Clearance

Status
Not open for further replies.

mull982

Senior Member
Does the NEC reference a minimum clearance from the side (end) of a 480V MCC. I am going back and forth with two parties, one saying there has to be 3ft the other saying there is no clearance issue.

The clearance issue I am refering to is a door which is on the same wall as the MCC but only 1ft away from the end of the MCC. I cannot find anything in the NEC that addresses this.
 

dnem

Senior Member
Location
Ohio
Is there a working space on the side of the cabinet ?
Or in other words, is there a removable panel on that side ?
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
The other question that should be asked is whether the manufacturer calls for a clear space on the side, perhaps for ventilation purposes.
 

mull982

Senior Member
The only working or removable panels that are on the side of the MCC are covers that cover the bus-bar in case future MCC sections are added. These covers would only be removed if additional sections were added.

To my knowledge the manufacturer does not call for clearance on the sides for ventilation or any other purposes.
 

Cold Fusion

Senior Member
Location
way north
mull982 said:
Does the NEC reference a minimum clearance from the side (end) of a 480V MCC. (cut) I cannot find anything in the NEC that addresses this.
The guiding NEC article is 110.26(1)(a). For most normal 480V MCCs, working space is not required on the sides, doesn't matter if there is a removable panel or not. And generally only needs 30" in the back. See if this code section applies to your installation.

cf
 

dnem

Senior Member
Location
Ohio
Cold Fusion said:
The guiding NEC article is 110.26(1)(a). For most normal 480V MCCs, working space is not required on the sides, doesn't matter if there is a removable panel or not.

That depends on the internal setup of the equipment. . If it is intended to be accessed/serviced from the removable side panel, then T110.26(A)(1) would apply to the side.

In the situation of the OP, I think he probably only needs to check for ventilation clearance on the manufacturers instructions which could be just about anything, zero inches, 3 inches, maybe 6 feet, who knows.
 

coulter

Senior Member
dnem said:
... If it is intended to be accessed/serviced from the removable side panel, then T110.26(A)(1) would apply to the side. ...
That's true. However, as cf alluded, I've never seen one (normal 480V MCC) that had servicable parts that required access from the side.

dnem said:
... I think he probably only needs to check for ventilation clearance on the manufacturers instructions which could be just about anything, zero inches, 3 inches, maybe 6 feet, who knows.
You're right he should check. However, again as cf alluded, I've never seen an MCC that required ventilation on the ends.

carl
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
dnem said:
That depends on the internal setup of the equipment. . If it is intended to be accessed/serviced from the removable side panel, then T110.26(A)(1) would apply to the side.

Just because there is a service panel on the side doesn't mean 110.26 (A)(1) applies.

It all depends on what the removable panel is there for. If it is only to add more sections, I don't think any clearance is required.

If its only to terminate the incoming line, nobody is going to do that hot, and you only need the clearance mentioned in the 1st paragraph of 110.26. (Just enough to do the terminations).

My guess is any testing or examination done hot would be done through the front. So I find it unlikely you will need 3' of clearance on the side.
Steve
 

mull982

Senior Member
I'm reading through the code now, and I agree that the MCC most likely wont be accessed from the side while "hot" and therefore does not require this clearance.

I'm not aware of any manufacturers specs for ventilation or anything as such.

Thanks for all of the responses.
 
Status
Not open for further replies.
Top