Business & farm

I realize I could have saved myself a lot of time by simply entering that 12% Home office expense for utilities under the 'Utilities' on Line 25 of Schedule C. And I would have bettered my bottom line refund by about $400. But I'm trying to do this the correct way & I am unsure if that line on Schedule C is appropriate for home office utilities -- maybe it's for an external office, I don't know.