Working Clearance

[vptran]

I have a MCC unit in an electrical room whose side is facing the door entrance. The front of the MCC meets the 36" working clearance, but I'm not sure if there is a rule specify a minimum clearance from the side of the MCC to the Door entrance.

After looking through the NEC 2005 code book section 110 for working clearances, I can't seem to find the part where the book specify if we need a certain distance from the door to the side of the MCC.

The reason why I ask this is because personnel will be going in an out, and we don't want them to have to twist and turn just to get in. Also, if we need to bring equipment in, we want to get it in through the door instead of forklifting through the roof.

Please let me know if anyone can help or have an idea of the minimum clearance needed from the entrance to the side of the MCC unit. The door is about 3 feet.

Thanks

 

[jim dungar]

Working clearance is only required in the direction in which you will be working. If the side panels of the MCC are not going to be removed while energized then your working clearance can be reduced. If the side panels are never removed then your clearance can be reduced even further. I have seen many MCCs with only 1/2" clearance on their sides.

 

[charlie b]

I agree. This is not an NEC issue. If you concerned about getting people and equipment in the door and past the MCC, that is a design consideration, not a code requirement. The building codes might have something to say on the subject of egress, but I cannot tell you anything about that.

By the way, is the current rating of your MCC 1200 amps or higher? If so, then that would bring a few more requirements to the party. Having one exit obstructed by virtue of inadequate space between the MCC and the door might become an issue.

 

[celtic]

Having one exit obstructed by virtue of inadequate space between the MCC and the door might become an issue.

I don't think that's an issue:

The door is about 3 feet.

Thanks

They "probably" have close to 40" on that side (including door bucks).

 

[W6SJK]

The front of the MCC meets the 36" working clearance, but I'm not sure if there is a rule specify a minimum clearance from the side of the MCC to the Door entrance.

What's the voltage? What's on the other side, i.e. behind you when facing the MCC? If its 480V and you have a metal or concrete wall behind you, then the clearance is 42".

And as posted above, if the MCC is 1200A or more and over 6ft wide then it gets more complicated.

 

[charlie b]

And as posted above, if the MCC is 1200A or more and over 6ft wide then it gets more complicated.

And if the local jurisdiction has adopted the 2005 NEC, the "over 6 feet wide" part no longer applies.

 

[vptran]

The amp rating on the MCC is 800A, 480V. I read the part in the code that specify systems that are 1200A or higher. It states that from the edge of the MCC to the edge of the door entrace, you have to abide by the minimum 3-1/2 feet clearance rule. But since the system is less than 1200A, I don't think that there are any code violations.

My initial thought was that this wasn't a code requirement, but wanted to double check. So thank you all for responding.

BTW...I just passed my EIT! I'm soo psyched. Now I need another year and a half of experience before I can qualify for the PE.