Pole Barn wiring and 300.4

Earl Olson

Member
Location
Minnesota
barn.jpg
The vertical posts are usually 6x6 or 4x6 posts. The horizontal boards are 2x4, laid flat against the post. This creates a 1.5" space between the vertical posts and the exterior steel siding. In the past, we've asked inspectors about wiring methods in these buildings, and have been given permission to run our MC cable horizontally, stapling to the top or bottom of these horizontal frames. We are not keeping the 1.25" clearance as required by 300.4(D), but I've always thought they allowed this because it is unlikely that new screws/nails will be installed on this finished building. Alternatives would be to run every wire vertically only, or staple on the interior of the 2x4s and drill through each post, or run emt, or...?

I just failed an inspection on some stapling problems in a pole barn. I have yet to verify the exact problems, as this inspector has previously allowed the horizontal top/bottom method in the past.

Any thoughts on wiring these? Are other inspectors specifically allowing this method or not?

Thanks!
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
View attachment 14399
The vertical posts are usually 6x6 or 4x6 posts. The horizontal boards are 2x4, laid flat against the post. This creates a 1.5" space between the vertical posts and the exterior steel siding. In the past, we've asked inspectors about wiring methods in these buildings, and have been given permission to run our MC cable horizontally, stapling to the top or bottom of these horizontal frames. We are not keeping the 1.25" clearance as required by 300.4(D), but I've always thought they allowed this because it is unlikely that new screws/nails will be installed on this finished building. Alternatives would be to run every wire vertically only, or staple on the interior of the 2x4s and drill through each post, or run emt, or...?

I just failed an inspection on some stapling problems in a pole barn. I have yet to verify the exact problems, as this inspector has previously allowed the horizontal top/bottom method in the past.

Any thoughts on wiring these? Are other inspectors specifically allowing this method or not?

Thanks!
If you're using MC on the front surface of the 2x4, why not wrap around the front of the 6x6/4x6 instead of drilling? Run above head height if someone thinks that exposure is too much.
 
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