ARC FLASH LABELING FOR BUSWAY PLUGS - IS IT REQUIRED?

[PE (always learning)]

I have a facility that has six main busway runs coming off of the main distribution panel at 480V. Each busway has bus plug taps at multiple locations along the busway. These bus plugs feed out to industrial equipment in the facility. My question is, do I require an arc flash label at each bus plug? When talking with the electrical contractor, it sounded like he was not planning on placing a label at each tap and that the facility would probably shut off the power to the busway when replacing fuses for equipment along the way. My questions is, are we required to provide labels at each bus plug? My intention was to not provide labels and tell the owner in the study that they are not allowed to work on the busway live.

 

[steve66]

I think its highly unlikely a facility will shut off power to an entire bus duct to replace a fuse or to open one disconnect.

 

[PE (always learning)]

I agree with what you are saying, that is why I set the instantaneous below the cleared fault threshold for the breakers located upstream of the bus ducts. This reduced the arc flash energy to a reasonable level. I have provided the facility with one label per bus duct run to place at the bus duct tap boxes. I would be curious as to how other engineers have provided labels for bus duct runs. The common solutions that I read seem to be one of these scenarios listed below:

• At the ends only
• At specific intervals
• At each bus plug
• We do not use bus duct

Let me know your thoughts.

 

[ron]

We provide stickers at each bus plug

 

[powerpete69]

We provide stickers at each bus plug

Each sticker at the each bus plug would be the same and represent the worst case arc flash for the three phase bus feeding the bus plugs?

 

[steve66]

Each sticker at the each bus plug would be the same and represent the worst case arc flash for the three phase bus feeding the bus plugs?

Probably, although for a really long bus duct, there could be a difference between the plugs at one end, and the ones at the other end.

 

[ron]

Each sticker at the each bus plug would be the same and represent the worst case arc flash for the three phase bus feeding the bus plugs?

As Steve mentioned it would probably be the same because we do the calc based on the line side OCPD protection with the possibly slightly less current due to the bit more impedance down the line..

 

[powerpete69]

As Steve mentioned it would probably be the same because we do the calc based on the line side OCPD protection with the possibly slightly less current due to the bit more impedance down the line..

Makes sense. The arc flash energy should be the same at the line side of all the bus plugs.

 

[wbdvt]

Depending on the client, we label the bus duct:
1. At just the beginning junction box.
2. Beginning junction box and at end
3. beginning jb, every x ft on alternating sides and end

Have never labeled bus plugs as they can be removed and reused elsewhere with the label still on it and what about new bus plugs - are they labeled consistently? Labeling bus duct itself alleviates those concerns.