Lessons Learned - Hooking up a Fire Alarm Panel for Monitoring

A recent incident has highlighted some issues to be aware of when selling or hooking up Fire Alarm monitoring. (And made me madder than a wet hen)

We sold a job where we were going to hookup an existing fire panel to a Vista 15 for monitoring (before you tell me - the structure wasn’t mandated as requiring monitoring of the fire alarm and the Salesperson mentioned in the quote that doing this way would not meet code).

Hey I wonder where the Black & White wires go?!

When the installer got on site he found that the Normally Closed side of the Alarm relay was being used by a pair of wires. 

Lesson Learned #1

Salespeople – you should always open the fire panel and confirm they have an unused relay available for the Alarm & Trouble outputs. You should always include in your quote that the customer needs to provide unused relays for us to connect to.

(Quite often the relay has already been used by an electrician to shutdown the HVAC system or release door holders).

If you don’t know how to identify them – ask someone - it's time you learned!

Technicians – if you go to hookup to a Relay and find it is being used by something else – STOP! Do not pass go – do not connect $200. Call the office and or the salesperson and tell them a relay is not available for us.

Also – before you go sticking your big fat conductive fingers into a panel when you don’t know what is being switched – get your meter out and measure it.

If you don’t know how to do that – ask someone - it's time you learned!

Yup - the relay is HOT!!!

As it turns out the other side of the relay was carrying 120VAC (did you think that tingling sensation you got while working on it was the result of getting that extra large Americano at Starbucks on the way to the site?!)

So now the zone is HOT!!!

So now we have 120VAC flowing down the wires and back to the zone on our poor innocent Vista 15 (who never did anything to deserve this kind of treatment).  

Just waiting to kill some poor sap!

This resulted in 120VAC going through the tamper switch and energizing the panel enclosure. (Admittedly a novel approach to deterring people from opening it but POTENTIALLY DEADLY! Google Electrocution or Fire Hazard if you don’t believe me).

Honest it’s true – look what we measure when we disconnect the zone going the Fire Panel Alarm Output.

that's more like it!

But wait there's more -

The Installer failed to ground the panel – if they had the problem would have become immediately apparent as the panel would have self-destructed (dramatically I suspect).

Lesson Learned #2  

Always ground your panel – LET’S REPEAT THAT – ALWAYS GROUND YOUR PANEL!  (The life you save may be your own).

Is that EOL....twisted round the wire?!

To top it all off the Installer twisted the EOL around the wires going to the zone.  Now in almost all other cases twisting and good conductivity is a wonderful thing, but think about this situation.

This EOL is across a Normally Open (NO) output.  It’s serves to supervise the zone;

If the zone resistance falls to zero (a short when the relay closes) – the panel sees that as an alarm on that zone;

Disconnected but still showing as closed!!!

If the zone resistance soars to infinite (an open circuit) the panel sees that as the zone being in trouble (having become disconnected somewhere along the circuit).

Because the EOL is twisted around the wire, it was possible to disconnect both legs of the zone without the panel seeing the zone in trouble.  THE WIRE IS COMPLETELY DISCONNECTED FROM THE DEVICE AND THE PANEL IS STILL FAT & HAPPY THINKING ALL IS WELL!


I guess we can be thankful the installer didn’t take the extra step of soldering the EOL to the wire before inserting it.



Lesson Learned #3

Always make sure that the EOL on any NO device is installed in such a way that it will indicate a trouble if wiring becomes loose.  Twisting it around the wire defeats it’s purpose.