A new law will affect the types of smoke detectors on sale in New York.  Brewster firefighters are alerting residents that as of April 1st, all new or replacement smoke detectors sold in New York must either be powered by a non-removable battery good for at least 10 years or be made to be hard-wired to buildings.  State officials say these types of smoke detectors can be safer because they do not require periodic battery replacements, reducing the chances of human error.  The law does not require the replacement of any existing smoke detectors powered by replaceable, removable batteries.