Cranford Controls


Product Overview

The MultiAmp-DH 250mA Door Holder Supply (DHS) provides up to 250mA of current at 24 VDC to operate door holders. The unit can operate as an “Automatic Door Release System” (ADRS) or respond to a secondary control.

When configured as an ADRS, conventional detectors are installed and connected directly to the DHS. The detection circuit is monitored for alarm, open, or short circuit conditions. The presence of any one of these conditions will deactivate supply to the door holders and cause doors to be released.

Alternatively doors may be released by a switched VDC input to the DHS, derived normally from a Fire Alarm Control Panel (FACP) or security system.
The switched VDC input must be between 8 to 30VDC to release the doors.

  • Mains powered 240vAC supply.
  • On board conventional detection zone.
  • Switches off DH power in alarm condition or atlernatively remote switched input can trigger the door to release.



Material High Impact ABS
Finish White

91mm H X 149mm W x 40mm D (Recessed)


91mm H X 149mm W x 53mm D (Surface)

Weight 400g packed

Power Supply


Mains Supply Voltage

230 VAC +/- 10% @ 47-63Hz

Door Holder Output Voltage

24 VDC @ 250mA

Operating Temperature

-5° to +45° C

Relative Humidity

25% to 95%

Zone Detection Circuit


No of Zones

1 (one), 2-wire system

Zone Monitoring

Open and short-circuit

Zone Current Load

4.8mA max

EOL Value

3k3 ohm

No of detectors/circuit

 40 (Max)



Switched VDC Input

Inactive state: 0 to 2 VDC

Active state: 8 to 30 VDC

Part Numbers

MultiAmp-DH Flush Mount 4510-1100
MultiAmp-DH Surface Mount 4510-1101