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The B401R plug-in detector base is used with System Sensor model 2451E photoelectronic detector head and model 1451E ionization detector head. The capability of plugging these detectors into a variety of special bases makes them more versatile than equivalent direct-wired models. Refer to the System Sensor catalog for other plug-in detector bases. The B401R base is intended for use in 2-wire systems, with screw terminals provided for power, ground, and remote annunciator connections. The B401R base also contains a resistor to provide current limiting in the alarm state.

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