What information would be required to make an arrest if someone was wearing a wire during a **** buy?

I am a lawyer in CT and practice in this area of the law.  The key components of the drug offense are that there is an intent to purchase and receive a controlled substance that is considered illegal to possess.  if the person wearing the wire gets the other person to acknowledge that that have drugs on them and will sell the drugs to the person wearing the wire for a particular price, this is sufficient to convict the person for attempted sale of drugs.  if the sale goes through, the person not wearing the wire is now exposed to selling and possessing drugs.  The admissions are what are important.

With regard to your specific question, the fact that the person was wearing a wire is not especially relevant.  What you need to keep in mind, however, is that in order for officers to effectuate an arrest, they need "probable cause" to believe that the individual committed the offense.  Therefore, if an informant (who is wearing a wire) is willing to testify that an individual bought or sold drugs, this is probably sufficient to establish probable cause.  Whether this would be sufficient to demonstrate the proof "beyond a reasonable doubt" necessary to convict, however, is another matter that will be left for the prosecutor and the defense attorney to argue about.