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Mounting Sub-panel next to Main Panel - space requirements?

16 years ago

My main 200 amp service panel, which is directly mounted on a basement concrete wall 21" from one corner, is full. I need to add several new circuits for a basement shop and plan to add a sub-panel. The most convenient place for this is adjacent to the existing main panel between that panel and the corner (21" of wall space). I have no problem with the 36" of working space in front of this wall. My question is this:

Can I install the sub-panel in this preferred location and still satisfy 110.26 A(2) that requires the width of the working space to be at least 30"?

My interpretation of this is that you need to have an adequate area in which to stand and work when servicing the electrical panels. I have read one opinion online where it was interpreted as meaning each panel needed it's own 30" of wall space. Since the sub-panel is only 14" wide, I will still have at least 3" of space between it and the main panel as well as between it and the adjacent wall.

As an alternative, I could always mount the sub-panel on the adjacent wall, so that it's facing 90 degrees to the main panel. The 36 inches of working space depth required for each panel would then be overlapping. Would this be a better approach?

Also, my understanding is that I should use a 1/2 inch plywood backer board behind the sub-panel rather than mounting it directly onto the painted cement wall. Is this required or just good practice?

Thanks for any help,


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