No, the roommate cannot turn off power to your room.
Is the roommate the property owner or a fellow tenant?
If the property owner turns off the power, you can demand triple rent for the amount
of time that the utility is off.
As has been said before, the breaker can't be flipped by the landlord or the roommate cutting off your utilities.
Assuming the roommate is doing this despite you paying them for utilities, the recourse would be to sue the roommate for the pro rata share of utilities you paid which they are withholding improperly. Also try talking to the roommate to resolve the problem which is, at this point, seemingly small compared to the way it will appear once it gets before any decider of fact.
This answer is provided for informational purposes only, does not constitute legal advice, and does not create an attorney-client relationship. Actual legal advice can only be provided after completing a comprehensive consultation in which all of the relevant facts are discussed and reviewed. www.AssociationAssessmentAttorneys.com
You have the answer to your question. Now practically, stay away from your roomate as best you can, or find another place to stay. Domestic issues can get messy and you can wind up in jail over nonsense.
Legal disclaimer: This answer does not constitute, legal advice nor does it constitute an attorney-client relationship. www.lygnoslawfirm.com Free Consultation 813 259-9494 Michael Lygnos, Esq., Lygnos Law Firm P.A., Serving Tampa Bay, Florida