The OH921 supports two operation modes: polarity insensitive mode and isolator mode. The Detector can be wired for either mode (refer to Figure 2 and 3). During the isolator mode, the built-in dual isolators will work at both sides of the Detector to isolate the line short in front or behind the device.
When the OH921 is wired in polarity insensitive mode, Line -6 and -5 can be either line of the loop.
When the OH921 is wired for Isolator mode, the positive line needs to be connected to 1b and the negative line to 6. The next device needs to be connected to 1b and 5. The Line Isolator is located between connector 6 and 5.
Ensure that the panel supports Isolator mode for the OH921 product version 17.
Isolator mode must not be used with a OH921 product version <17. You will find the product version number on the detector label.
OH921: S54320-F6-A2 ⑰
Polarity insensitive wiring:
Isolator mode wiring:
Wire size: maximum 14 AWG, minimum 18 AWG (Wire larger than 14 AWG can damage the connector)
HLIM isolator module and SBGA-34 sounder base cannot be used in the same loop with the modules in isolator mode.
In the device line, up to 30 of any compatible devices in polarity insensitive mode with 20 ohms max line resistance can be isolated between two modules in isolator mode in a Class A Style 6 wiring. In the device line, up to 30 of any compatible devices in polarity insensitive mode with 20 ohms max line resistance can be isolated behind one module in isolator mode in a Class B Style 4 wiring.