I recently got a Ground Fault on my Mircom FA1000 board.
The ground fault light comes on and goes away every few seconds or minutes.
I tried to set ALL the signal switches to the Disconnect position. Then yet, I got the Ground Fault light come on and off in a few seconds.
Could this be a bad board or board going bad?
I couldnt see a wiring diagram online other than the user manual on the mircom.com website.
Any help, suggestions or hints are greatly appreciated.
Mark
Does the ground fault light flash intermittently, or at a steady rate? From the Manual available here: http://firealarmmanual.com/index.php?option=com_mtree&task=att_download&link_id=68&cf_id=24
If it is flashing at the 20 per minute Trouble rate, then the problem is most likely a simple ground fault that has developed within the field wiring. I know you mentioned that you disabled the signaling circuits, but this still leaves the zones and other connections that the panel monitors. If the LED is flashing intermittently and seemingly without reason… things don’t bode well for the panel. First of all before we start helping you, is this panel installed in a real life safety system in a building, or is it a hobby/testing panel? Being installed in a building brings about a challenge in trouble shooting this type of fault, in addition to other obvious issues such as certifications and liability of people working on the system.
Thanks Nick, for the response.
I couldn’t find a circuit board diagram in the manual except for page 20 for field wiring, which i am trying to figure out how to get those on the actual board by looking if there are any printouts on the actual board. I have to take a good flash light next time to do a better inspection.
The ground fault doesnt blink at the rate of 20 per minute, however it does come on and stays on for sometimes 2 to 3 seconds and then goes away for few seconds, or several minutes. Quite random really.
The system is in a live building, so I am only testing this when i call the monitoring company and put the system on test mode, so i can do any testing with my multi-meter. I am wondering if I should use a oscilloscope to check the frequency of the faults, to get a rough idea of what it could be.
At worst case, I would have to call some company to do the testing/fault finding.
Thanks
Mark
Sounds like you have an intermittent ground fault on the field wiring. What is happening is a bare conductor is touching the metal of the building somewhere. Could be inside a junction point or a nicked jacket on the cable that is wedged in a metal support. Can be very difficult to trace out depending on the size of your building and how many devices you have on the fire alarm system. There is a process to tracing it out but unless you’ve worked on fire alarm systems could be dangerous to try. You may end up smoking your panel or compromising your fire protection so best to just call a tech out for this one. Just be patient, may take a couple of trips to resolve. Intermittent ground faults are the worst ones to trace out.
Also, have you had any work done where contractors have been working about the ceiling? We recently ran into a situation where someone had a company install security cameras throughout the building. The guys running the wire burnt the heck out of a fire alarm cable and caused all kinds of problems. May be a good area to start looking for a ground fault.
Here are a few other places to look for intermittent ground faults.
Post Indicator Valve (PIV) for the sprinkler system. These are outside so the conduit to them can get full of water. The wiring at the PIV can be damaged by lawn mowers and other landscape tools. These types of damage can cause a ground that is not a short but is near the fire alarm panel’s threshold to report a ground fault. A high resistance ground.
A PIV or any other outside wiring should have a transient suppressor to protect the system from nearby lightning activity. These can develop leakage and cause ground faults. They should be placed at the location where the outside wiring enters the building.
Anywhere there is a leak in the building or condensation near a fire alarm device. Rusted or corroded terminals and wiring can also cause a high resistance ground fault. These can wander in and out at the panel as the corrosion conducts more or less current.
The ground can be on a panel circuit board. All modern fire alarm panels have MOVs (metal oxide varistors) across all circuits and from all circuits to ground. MOVs have an infinitely high resistance up to their threshold voltage and then conduct. If one or more of these are damaged by nearby lightning or other transients they can leak and cause a high resistance ground that goes in and out at the panel. Most panels now use surface mount technology components which are not economical to troubleshoot and replace. This takes a new board and the old one goes to be recycled.