Douglas Krantz - Technical Writer - Describing How It Works
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How do I Wire a Replaced Tamper Switch?

When the old tamper switch has been removed because valve has been replaced, the first thing is to determine if the old switch was wired as a trouble or supervisory tamper switch.

A typical tamper switch assembly has two switches that can be wired independtly.

Greetings Douglas,

Our fitters recently replaced a leaking butterfly tamper. Now they have taken all the parts including the box and EOL, leaving the wires bypassed on Mircom FA 1000 panel.

With the new Globe tamper shut off valve, I want to know how do I wire it to the tamper to supervise the valve? I have 2 pos wire and 2 neg wire. 1 pair has the voltage, the other pair has none.

Which one of the many tamper wires will I connect my 2 pairs of pos and neg? And, which goes to the EOL? I don't understand the diagram either. . .

Thank you, GL

I've seen this kind of thing done before. The sprinkler fitters fix the sprinklers; if they worked on fire alarm systems, they'd set off the alarms. The fire alarm people fix the wiring; if they worked on sprinkler systems, they'd make a mess. This is why the sprinkler fitters didn't rewire the new tamper switch.

Download a Copy of the Manual of the Fire Alarm Panel


http://www.mircom.com/media/manuals/LT-600_FA-1000_Installation_and_Operation_Manual.pdf

All companies have lots of information on their systems. This one is available as a PDF you are able to download. When you are working with something you aren't sure of, look it up on the web and download. Then read the information. This is how you learn.

Put It on Test

Always put the system on test, or no action with the monitoring company. Nothing changes with the building's fire alarm system, but at least they won't take the action of calling the fire department.

No matter what you're doing with the fire alarm system, something may happen (like a smoke detector you're not even near goes into false alarm, it's happened to me) and you don't want to have to explain things to the arriving firefighters.

Trouble or Supervisory

There are two ways of wiring a tamper switch; Trouble or Supervisory.

Trouble wiring is the old fashioned "Use-the-Tamper-Switch-to-Break-the-Wires-to-the-End-of-Line-Resistor" method that sends a trouble signal to the fire alarm panel when the valve is tampered with. This way is grandfathered in old buildings.

Supervisory wiring is the new, common "Use-the-Tamper-Switch-to-Short-Out-the-Wires" method that sends a supervisory alarm to the fire alarm panel when the valve is tampered with. This is the way that's specified in the Code now.

To get a general idea of the different ways of wiring, go to:

Why Does Closing Some Gatevalves Show Trouble?

Before trying to wire anything else, you have to figure out whether the old switch was wired to send Trouble to the fire alarm panel or Supervisory to the fire alarm panel.

Go to the fire alarm panel and look to see what zone is bypassed.
  • If the zone that was bypassed (that zone will be in trouble) says something like FLOW, the tamper switch was probably wired in the old-fashioned Trouble method.

  • If the zone that was bypassed (that zone will be in trouble) says something like Tamper, the tamper switch was probably wired in the common Supervisory method.

By Douglas Krantz Douglas Krantz Check It Out

Confirm the Method

Now is the annoying to everyone part. You have to know that you are doing it correctly, so you have to try it. Trying it may set off the alarms, so have someone standing at the panel to press "Signal Silence" to stop the alarms while you're trying something at the tamper.

Use this as a training session for the management or the maintenance person for the building, they'll be more comfortable running the fire alarm panel if they are allowed to press buttons during this exercise. When you are testing, remember that the alarms may sound off, and the horns and strobes may sound off. When this happens, "Signal Silence" will stop the noise, but allow you to see what happened.

DO NOT RESET THE FIRE ALARM PANEL. You need to look at the panel to see what happened. Resetting the panel can prevent you from seeing what zone actually went off. After you know what happened, you can reset the panel.

Before testing, make sure that none of the wires at the tamper switch are touching any of the other wires. Now you can go back to the panel and un-bypass the zone. The zone should still be in trouble, but the zone won't be bypassed; it can go into alarm.

End of Line Resistor

There are two pairs of building fire alarm wires at the tamper switch.
  • One pair is connected to the panel. Use your voltmeter to confirm this pair has voltage. Do not use your ohmmeter on this pair, or the alarms might sound.

  • One pair goes to the end of line resistor somewhere else in the building. This pair does not have voltage. Use your ohmmeter to confirm whether or not this pair has the resistance of an end of line resistor.

Short the Wires to the Panel

This is the risky-alarmy noisy part. This is part that you need the person at the panel, ready to press "Signal Silence". Again, DO NOT PRESS RESET at this time. You will need to read the panel, and pressing reset clears the alarm.

Short these wires together. This is what a waterflow switch does to send an alarm to the panel, and if the tamper switch is wired as a Supervisory switch, this is how a tamper switch sends a supervisory signal to the panel.

Alarm or Supervisory

By shorting the wires, you have done exactly what the tamper switch does if it is wired as a Supervisory tamper switch. Go to the panel and read the panel.
  • If there is a red-light alarm showing on a waterflow zone on the panel, the tamper switch is not wired as a supervisory. The tamper switch is probably wired to send an old-fashioned Trouble.

  • If there is a yellow-light supervisory showing on the panel, the tamper switch is wired as a Supervisory.

Don't try resetting yet. Bypass the zone again so you won't set the system into alarm again. If the panel was in red-light alarm, once the zone is bypassed, you can reset the panel.

Remove the short you put on the wires.

Pigtails to the Tamper Switch - Which Wire is Which?

Two Switches - Inside the switch assembly are two separate switches, one is for fire alarm use and one is for non-fire alarm use. They each turn on or off at the same time as the valve is opened or closed.

Three Groups of Wires:
  1. Green - Ground Wire

  2. Three Pairs of Wires going to the Fire Alarm Switch - Each pair is a different color. To the person looking from the outside, each colored pair of wires can be considered to be a single wire. The ends of each single wire is on the outside, and the middle of the wire is connected to one of the contacts of a switch. One pair of wires goes to the "common" contact, one pair of wires goes to the "Valve is Open" contact, one pair of wires goes to the "Valve is Closed" contact.

  3. Three Individually Colored Wires going to the Non-Fire Alarm Switch - One wire goes to the "common" contact, one wire goes to the "Valve is Open" contact, one wire goes to the "Valve is Closed" contact.

Which Wires are Normally Open and Which Wires are Normally Closed?

I'm assuming that the valve is open at the moment. When it's left open by the sprinkler fitters, closing it temporarily probably won't harm anything. When it's been left closed by the sprinkler fitters, just leave it closed.

Use the Fire Alarm Switch Wires. While the valve is still open, using the ohmmeter, find the two colors of wires are shorted together. Mark both of them with tape.

Now close the valve. With the ohmmeter, find the two colors are shorted. Mark the one with tape with a second piece of tape, right next to the first piece of tape.

You have now figured out that the color that has two pieces of tape is the "Common" wire. The color with one piece of tape is the "Normally Closed" or "N C" color, and the color without tape is the "Normally Open" or "N O" color.

Wire the Switch

If It's Supervisory Wiring

Supervisory wiring is the new, common "Use-the-Tamper-Switch-to-Short-Out-the-Wires" method that sends a supervisory alarm to the fire alarm panel when the valve is tampered with.

If you determine that it's a Supervisory Tamper, use the diagrams in the manual for the panel. (You should have downloaded it by now.) The manual has the wiring diagram for a Supervisory; it shows how to wire a flow switch or a tamper switch. Remember to use the tamper switch's Common wires and the Normally Open wires.

If it's Trouble Wiring

Trouble wiring is the old fashioned "Use-the-Tamper-Switch-to-Break-the-Wires-to-the-End-of-Line-Resistor" method that sends a trouble signal to the fire alarm panel when the valve is tampered with.

If you've figured out it's a Trouble Tamper, connect the black wire that goes to the panel to the black wire to the end of line resistor. Then connect the red wire to the panel to one of the tamper switch's Common wires, and connect the red wire to the end of line resistor to one of the tamper switch's Normally Closed wires.

Cap Off All the Unused Wires

Unused wires short-out to boxes, unless they're taken of. Cut off any actual wire that isn't insulated, attach one small wire-nut to each unused wire, and just to make sure, use electrical tape to cover the end of each unused wire. Make sure none of the unused wires can short out to any other wire, or to the box.

CYA Paperwork

Remember to do your CYA Paperwork. Explain in the paperwork that you wired the tamper switch, and that you (or the sprinkler fitters) tested every flow switch and tamper switch in the building. (Or explain why you didn't.)

Remember with paperwork, no one will read your paperwork, unless something goes horribly wrong. When something goes horribly wrong, then everyone will read it. Make sure it says what you did, and that it was tested.

Douglas Krantz Douglas Krantz
Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer
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facpdoug@douglaskrantz.com
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