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[Hayden J. Nebus]

I have a 3Ø IG sequencing panel with novelty sized neutral feeder pulled to it. The proper lug won't fit the neutral bus bar in situ, due to tight clearance.

The EC would like to mount 2 additional lugs, properly sized for the neutral feeder, and use a jumper of the largest diameter conductor the panel lug allows to tie it in.

Wouldn't removing the panel lug and adding a piece of bus bar better serve the purpose of having an oversized neutral?

[Cailen Waddell]

What does the panel manufacturer say?  What does the electrical engineer say? 

[Frank Koenig]

I have a 3Ø IG sequencing panel with novelty sized neutral feeder pulled to it. The proper lug won't fit the neutral bus bar in situ, due to tight clearance.

The EC would like to mount 2 additional lugs, properly sized for the neutral feeder, and use a jumper of the largest diameter conductor the panel lug allows to tie it in.

Wouldn't removing the panel lug and adding a piece of bus bar better serve the purpose of having an oversized neutral?

A picture would really help. -F

[Stephen Swaffer]

Cailen voiced my first thought.

My second-is why is the neutral oversized?  I am working on a project now where I will run 500 MCM wire for a service I would normally use 4/0 because of distance and voltage drop.  In this case, I will likely use reducing lugs, or splice onto smaller wire to terminate since my breakers etc. do not have lugs that will handle 500 MCM. 

If, as I suspect, the neutral is oversized to allow for neutral currents caused by nonlinear loads, the EC may not understand the neutral load well enough to make the call to undersize the neutral, even for a few inches (that is otherwise known as a fuse-if Bussman does it) and properly sized bus bar might be the better answer.

[Hayden J. Nebus]

Cailen voiced my first thought.

My second-is why is the neutral oversized?  I am working on a project now where I will run 500 MCM wire for a service I would normally use 4/0 because of distance and voltage drop.  In this case, I will likely use reducing lugs, or splice onto smaller wire to terminate since my breakers etc. do not have lugs that will handle 500 MCM. 

If, as I suspect, the neutral is oversized to allow for neutral currents caused by nonlinear loads, the EC may not understand the neutral load well enough to make the call to undersize the neutral, even for a few inches (that is otherwise known as a fuse-if Bussman does it) and properly sized bus bar might be the better answer.

The feeder run is about 50ft to the transformer. The oversized neutral is in fact to accommodate unbalanced loading. The spec was more a piece of the consultant's boilerplate design spec than a requirement by an EE.

Your fuse comment seems to echo my sentiment. I did ask yesterday about a reducing lug and the "more lugs" approach was suggested.

We'll see what today brings. I'll roll lyntec into the conversation and set up a call w/ the EE if necessary.

[Cailen Waddell]

I would definately roll lyntec into the discussion.  I have always found them to be knowledgable, and good. Chances are, if the consultant is good, they have dealt with this before.  And for that matter I would ask the consultant how other installs have handled the situation.  That may not give you the right answer but at least some other starting places.


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[Hayden J. Nebus]

This did get a reducing lug.
https://drive.google.com/file/d/0B0pQLbAUdKDhNEd2akRPbnIzTlk/view?usp=sharing

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