You need to review your title and survey, if one was taken when you purchased the property. If you believe that your neighbor is trying to gain ownership of your property, consult with a real estate attorney to consider a quiet title action.
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Typically in Tennessee utility providers are granted easements along lot lines as a condition of developing a subdivision. If that is what your neighbor relies on, then he is incorrect about ownership. The lot line of record determines the ownership, and the property on either side will be subject to the utility easement which is owned on a non-exclusive basis by the utility companies. If your neighbor is claiming an ownership interest on your side of the lot line, then whether he is correct depends upon other factors such as obtaining a prior deed or his [and/or his predecessor in title] open and hostile use of your property for a long time, or his payment of taxes on the disputed property and other circumstances. If you are concerned with any of that, then, yes, consult a real estate lawyer in your county promptly.
These comments do not constitute legal advice. They are general comments on the circumstances presented, and may not be applicable to your situation. For legal advice on which you may rely consult your own lawyer.