I have not researched the issue of the composition of the "equipment" to which the law refers..........but it appears to me that the intent of the law was to be very broad in application..........example, allows the credit to be applied to houses which are not principal residences.........that is usually a restricting requirement.

If you want to see what Congress intended, go to the Conference Committee reports...........every law has a record of what the Conf Com comments were, and those comments help many times to better define unclear phrases, etc.    Might be something there, might not.

If you go to publications by the IRS, those descriptions will be quite vague, and, if typical, will be slanted on taxpayer paying tax...............................there might be some "Q&A" sheets at their website on the issue--------just have to look.  Just remember, the information sheets are not always correct as to the law------that is why there are still court cases on the subjects.  Those sheets are prepared by the IRS..................'nuff said.

The bottom line is what your preparer will sign or not sign..............if they are doing their job, they will research the issue to the extent they are comfortable one way or the other, document that research in the event of an audit, and finalize the return.

The importance of that documentation by the preparer---------in the event of an audit, and the IRS disagreeing with the position taken.........

.......you the taxpayer can use as a way to avoid the negligence penalty, ie the mistatement of tax penalty, that you were relying on the technical competency of the preparer.   IRS will then look to the preparer to determine if the taxpayer had a logical basis for such reliance.    If you are using Charlie the part-time preparer-who-sells-insurance-the-rest-of-the-year.............you will   obviously   have less chance of avoiding the penalty than if you are using a CPA firm with a local reputation for tax work.

If they are convinced that intentional disregard for the law did NOT exist, they will not assess the penalty, resulting in the assessment of the tax that you would have paid anyway without taking the deduction/credit, plus interest. 

So............even if you take the credit, and you are not correct--------BUT there was logic and reasonable basis for such position, the cost is minimal..............ie essentially the same position as if you had not engaged in the endeavor anyway. 

 I have had "men of the cloth" look me in the eye, and say----------decide all grey areas in favor of the govt............................and, I have had "men of the cloth" look me in the eye, and say----------decide all grey areas in favor of  ME.

So.............have your tax person do his homework, provide you with a decision AND REASONS for that decision............and go for it.

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A final comment...............I have talked before about all tax returns paint a "picture".   Looking at a persons return, if it is prepared properly, and has descriptions in it.................USUALLY says a lot about a person's financial structure. 

Given that "picture"-------------sometimes it is hard to understand why certain items would exist in it.   

Example................person shows 10K of wages on line 7, and a loss of 50K on sch F.............and yet shows 25,000 of investment in geothermal equipment..........which means the taxpayer is probably building a new house also.

I would likely put a statement with the return indicating why the lender believed that the taxpayer was financially able to swing the investment in a new house that would have 25K of "extraordinary" capital investment..........something like "losses for the year are not usual to taxpayers business history, which is for the last three years taxable incomes of    xxx, yyyy,   zzzz.   Contractors indicate that the investment of xxxxx in geo thermal will have a payback of zzz years, and lender is enthusiastic about this addition."   Of course, it all has to be true...........and have substance-------more than my example.

If the return were showing 150K of salaries...........and no losses related to a business which typically requires large capital investments............no comment would likely occur.

Example...........we have client who is medical doctor.............lives in an extremely "high priced part of town" which is known nationwide...................makes about a gagillian per year..................but whose interest on home mortgage is gigantic..............more than what could be justified even on his salary/income.    We put a statement in tax return every year indicating that he has a source of funds not usual--------ie, the classic "trust fund baby".

Does it help avoid audits??    I don't know............I think so...........the tax gurus think so..........but we really don't know for sure.  Logic says it ought to, since the statement becomes part of the return, ie an "affidavit" by the taxpayer, just like number information.