Edwards Field Notes Bulletin - Electromechanical Noise on Hazardous Location Horns

Notes Bulletin E C H N I C A L S U P P O R T N 1 3 0 0 2 E Signaling Electromechanical on Hazardous Location Horns a previous AE Bulletin 040510 the effects of electromechanical devices on alarm signaling circuits was discussed This bulletin will revisit what was on the first one and to offer some additional information and devices such as bells and explosion proof horns can a lot of electrical on the wires they are connected to when they operating This noise can cause random troubles on fire alarm panels and power supplies as well as other electronic signals including strobes that not flash properly To help alleviate this problem there are some preliminary that should be taken offers a bipolar transient protector part number 235196P which should installed across the incoming plus and minus of the first electromechanical on a NAC signal circuit In addition the device should be located at least feet away physically not just wire length from the fire alarm panel or booster supply see Figure 1 13002E ISS 19FEB13 2 1 Bipolar transient protector min to device Panel NAC for electromechanical devices should also be separated from any type devices such as strobes as much as possible This means they be on their own NACs and the wiring should not be run in the same or share junction boxes with wiring for electronic devices The electrical could be induced into the other circuit wire if they are not kept apart If a area within a building requires both a horn and strobe the two devices also not be mounted right next to each other the above steps should help in most cases it may not in all Depending on installation the devices used and the panels they are connected to measures such as longer wire separation between panel and devices even using twisted pair wire for the NAC may be required support 1 800 336 4206 1 860 284 3083 13002E ISS 19FEB13 2