Single tone alarms have a Euro-connector that can accept two power wires - positive and ground. For DC only units, the connector is on the left side of the alarm. Insert the stripped positive wire in the left connector receptacle and the stripped ground wire to the right connector receptacle. For AC or DC units, the connector is on the right side of the alarm. If the application is truly AC, there is no polarity and the two power wires can be inserted either way. If the application is applying DC voltage to an AC/DC model, Insert the stripped positive wire in the left connector receptacle and the stripped ground wire to the right connector receptacle. The alarm label shows the positive plus symbol and the negative minus symbol above where the wires go. The recommended strip length is 6.5 mm or 0.256 inches. The wire gauge can be from 16 to 30 AWG. The maximum screw torque is 2 inch-pounds or 0.226 newton-meters.