Sunday, March 29, 2015

Fire Alarm Underground Conduits

Is it OK to Install Fire Alarm Cable underground?

PIV Post Indicator Valve for Fire Alarm Sprinkler System
Post Indicator Valve  with Fire Department Connection
A common task when installing a new fire alarm system is undergrounds. Typically when a C-16 or fire protection (fire sprinkler) contractor installs their incoming lines they will at the same time install the necessary fire alarm underground conduits for the connections to the backflow prevention switches (OS&Y Outside Screw and Yoke) or PIV (Post Indicator Valve) switches. However, sometimes this task could be a part of the fire alarm contractor's scope of work. If you find yourself installing underground conduit or direct burial cable make sure to follow all of the national codes and regulations.

Direct Burial Cable as an Alternate to Conduit

Backflow Preventor OS&Y For Fire Alarm Sprinklers
Backfloe Preventor with OS$Y Switches for Fire Alarm
Some contractor's may choose to use direct burial cable also referred to as UF Cable commonly identified by its grey coating. Direct burial fire alarm cable not protected in conduit must be installed at a depth of 24" below grade with either schedule 80 PVC or Rigid conduit stubs up to your box. When fire alarm cable is installed within plastic conduit it must be 18" deep and installed with schedule 80 PVC. This is a more durable plastic conduit (grey color) than the common household irrigation lines. The best way to install these conduits or cable is with a Ditch Witch. Simply set the depth and go.

Junction boxes that are run out into the middle of a remote area without an anchor point must have the schedule 80 PVC embedded in the concrete to support the box. Another method is to attach the box to a post that is either driven or buried in the ground 18" and connects directly to the schedule 80 PVC conduit. Junction boxes should be installed at least 12" above grade but not more than 18" for the unattached method.

See also conduit bending videos.

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Wednesday, March 25, 2015

Wheelock LED Notification Appliances

Are the new Wheelock LED Series Notification Appliances all They're Cracked up to be?

Although the Wheelock LED (Light Emitting Diode) notification appliances are not so new anymore, they still seem to bring up quite the conversations.  Like any new fire alarm equipment, it is wise to let them prove themselves before you actively start specifying and installing them throughout all of your sites.  Well that time has come and gone as these LED strobes and horn/strobes have been flying off the shelves.

Our goal here is to make you aware of their capabilities so that you can decide when and when not to include them in your fire alarm system design criteria.  For this comparison I am going to be using the new Wheelock LED Series Horn/Strobe (model LHS) and the Older Wheelock Exceder Series Horn/Strobe (model HS).  Note that both models comparisons will be based off wall mounting, 24 VDC, 3 Tone Temporal Output, and set at the High Setting.  This should keep everything fair for the sake of the article.

Lets take a look at differences and similarities of the two notification appliances.

As you will notice from the chart I created above, the two notification appliances have quite a few differences.  One of the more noticeable differences is the candela selection available.  You can see that the Exceder series covers standard candela all the way up to high candela at 185 CD.  On the other hand the Wheelock LED series appliance only covers the standard candela range.  

Wheelock LED Series Horn Strobe LHNow the biggest item that everyone is discussing around the new LED series strobes is the lower current draw.  We all know the lower the current draw, the more appliances we can fit on a circuit. More appliances on circuits results in few circuits, and less remote power supplies.  As you may notice in the "Current Draw" tables above, the LED series appliances have a lower current draw through the range of 15 CD - 75 CD.  Once you jump up to 110 candela, the standard Exceder series with Xenon bulb actually draws less.

Wheelock Exceder Series Horn StrobeIt all depends on you application as your facility may demand more 110 candela strobes in comparison to your lower levels (15-75).  In this case you would probably want to stay with the older Exceder Xenon bulb technology.  Now if you have an office building with multiple corridors, you can get away with 15 candela and the LED strobes would be your best bet.

*It is also very important that I make you aware that Cooper-Wheelock has made it clear that both the Xenon bulb and LED style visual appliances are compatible on the same circuits and will successfully SYNC if you use the proper remote power supply or sync module such as the DSM-12/24.

I hope this information assists you in your design as both models are great products with their own special characteristics.

Elevator Recall and Shunt Trip Wiring Methods

We have created an easy to follow document for the proper wiring method with elevator shunt trip functions.  This document includes two methods both based on the supervision requirements of NFPA 72 2013 edition section A21.4.4.

Below is a sample picture of the document that is available for download on our Facebook Group.

It is important to remember that the wiring between the FACP/FACU and the ECID (Emergency Control Interface Device) needs to be supervised.  In one method below, we are using an addressable relay module (FRM-1) to operate the shunt trip breaker directly.  With this wiring method, only the wire to the FRM-1 (SLC) needs to be supervised.  This is obviously achieved through the SLC and addressing of the device.

In the alternate method, we are showing you how to properly wire up the equipment when the load of the circuit exceeds the rating of the FRM-1.  In this case you would need to install a PR-1 interface relay (rated for 10 amps).  Now that you have a PR-1 switching the shunt trip circuit, this becomes your ECID (Emergency Control Interface Device) and the wiring up to this relay needs to be supervised.  To save the cost of an additional addressable monitor module (FMM-1) we can switch out the FRM-1 with a FCM-1 (addressable control module).  By doing this, we can achieve supervision as well as activation of the PR-1 interface relay through one device.

Elevator Shunt Trip Wiring Diagram

Make sure to download the document and let us know your thoughts.

Tuesday, March 24, 2015

Fire Alarm Testing Corrections Made Easy

How do you mark the devices that need a return service trip to correct?

When you are performing a fire alarm system test or fire alarm system pre test, make sure to check every fire alarm device and notification appliance.  This includes audible visual, smoke detectors, heat detectors, pull stations, Ansul (hood systems), door holders, and the one everyone skips, duct smoke detectors.

When checking these devices it may become a burden to write down the exact location of a fire alarm device or appliance that did not function correctly.  This really applies to non addressable devices as these devices have a location/description programmed into the fire alarm control panel. Devices such as conventional initiating devices, strobes, horns and speakers are harder to keep track of.  

Here is a little trick that will help shave time off your fire alarm test.  Use small bright yellow colored stickers to mark the fire alarm devices or appliances that did not function correctly.  This will make it easy to come back and check or note deficiencies.

Wheelock RSS-24MCW Wall Mounted Strobe

With door holders, you can mark the actual magnetic holder if it did not release, or you can mark the hardware mounted on the door if the door did not close and latch.  It makes it easy to come back and accurately make notes on your fire alarm test form otherwise know as the NFPA 72 testing and inspection sheets or the Record of Completion if a new system.

You can also get creative and use different colors for different scenarios.  For example, lets say you have a duct smoke detector that went into alarm but did not shut down the air.  Use a green sticker for HVAC shutdown.

Try it out and let us know what you think.

Make sure to join our Fire Alarms Online Facebook Group HERE.

Elevator Shunt Trip with Sprinkler Heads

What is Elevator Shunt Trip?

Elevator shunt trip wiring deta
Elevator Shunt Trip Wiring Detail
Elevator controls play a huge role in fire alarm system emergency functions. Whereas elevator recall captures and sends the elevator cab to safe floors, shunt trip works a little different.  Elevator Shunt Trip is a function that involves shunting the breaker that controls the elevator equipment prior to the release of the automatic sprinkler systems.  This procedure is completed via the activation of heat detectors (addressable or conventional).  Now keep in mind that not just any heat detector within the facility will be required to activate the elevator shunt trip procedure.  The only heat detectors that will tell the fire alarm control panel to shunt the elevator breaker are the ones located in the elevator shaft or hoistway and elevator equipment room.  Per NFPA 72 2013 edition section 21.4.2* the heat detectors that are in place to shunt the elevator power shall be installed within 24" of each sprinkler head within the area.  On top of this section 21.4.1* states the heat detector used for shunt trip shall be set at a lower temperature and higher sensitivity than its adjacent sprinkler head.

One last thing, the activation of heat detectors can delay the shunt trip via programming for a delay time not to exceed the time it takes the elevator cab starting at the top level to reach the lowest level of exit discharge.  The purpose behind this allowance is to increase the potential for elevators to complete their travel to the recall level.  Make note that the requirements of A17.1/B44 Safety Code for Elevators and Escalators would still apply.

Now if you choose to use the method of waterflow or pressure switch to activate you elevator shunt trip, any time delay switches or capability will not be permitted per NFPA 72 2013 section 21.4.3.

When the shunt trip breaker is activated, the breaker switch itself will be between on and off.  To reset the breaker, make sure the controlling fire alarm system is reset and back to normal.  Once the FACP is reset, flip the shunt trip breaker all the way towards the off position (should be some tension) and then flick it all the way back to on.  Review the short video for more details on resetting a shunt trip breaker.

Code References for Elevator Shunt Trip:

ASME A17.1-2004 In jurisdiction not enforcing the NBCC, means shall be provided to automatically disconnect the main line power supply to the affected elevator upon or prior to the application odf water from sprinklers located in the machine room or in the hoistway more than 600 mm (24") above the pit floor.  This means shall be independent of the elevator control and shall not be self-resetting.  The activation of sprinklers outside of the hoistway or machine room shall not disconnect the main line power supply.

ASME A17.1-2013 In jurisdictions not enforcing the NBCC, where elevator equipment is located or its enclosure is configured such that the application of water from sprinklers could cause unsafe elevator operation, means shall be provided to automatically disconnect the main line power supply to the affected elevator and any other power supplies used to move the elevator upon or prior to the application of water. (a) This means shall be independent of the  elevator control and shall not be self-resetting.

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