Bus Duct Plug Clearances

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apjpe

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I have a situation where a 400Amp fused bus plug is located above a 100Amp fused bus plug. The 400A plug is 9 inches deeper than the 100A plug. The local inspector has not passed the job on the basis of 110.23 A (3) which states that the maximum distance equipment can encroach into the working height of other electrical equipment cannot be greater than 6 inches. In this case, the 400A plug encroaches into the working height of the 100A plug by 9 inches.
I called the bus plug manufacturer and they had never heard of this. Surely this is not the only time this has ever happened. I can't get him to budge and the manufacturer will not budge. Has this happened to anyone else?
 
This is an interesting scenario. I would say that technically the inspector is correct but this problem exists in thousands of installations. I would check the difference in depth between the 400 amp switch and a 200 amp. If the difference is 6" or less than I would swap out the 100 with a 200 amp.

By the way, welcome to the forum.:D
 
Any chance that the physical layout would allow you to mount the two bus plugs on opposite sides of the bus?
 
Bus duct switches rarely meet the all the requirements of 110.26, most inspectors in my experience exercise common sense when considering placement.

That said I believe the inspector can enforce this 6" rule.
 
There is no chance of mounting them on the other side because it's up against a wall. Again, I'm sure this happens all over but I can't find a basis to challenge the inspector. Thanks for the input though.
 
Is there anything in the instuctions/listing and labling that says you can?

110.3(B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
 
I had the same situation on my job but I caught it before installing and made the Manufacturer change the Plug to 600 Amp fusible with 500A fuses and tap to a 100 Amp wall mount disconnect. Cutler Hammer is notorious for making this mistake and their bus risers at times do not even offer enough room to plug both bus plugs in. The flip side is this is an authorized space because of the Bus Amperage nobody but an electrician would work on it anyway. I cant imagine any Electrician working on bus live anyway.
 
cesenergy said:
= The flip side is this is an authorized space because of the Bus Amperage nobody but an electrician would work on it anyway.
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What does the 'bus amperage' have to do with it?
 
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