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October 3, 2004

[]<                            ET NEWS                                 
====================================================================== 
             NEWS AND INFORMATION FOR THE ENGINEERING TEAM
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Issue No. 171   http://etnews.org   mailto:mike@etnews.org   10-3-2004
====================================================================== 

Contents
--------
- News
- ET News Journal
- Job Opportunities
- Fire Alarm Class Schedule
- Comments & Acknowledgements

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NEWS 
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STATE fire marshal fired by Blanco
Baton Rouge Advocate - Baton Rouge,LA,USA
... The office also inspects amusement-park and carnival rides, and licenses
people who sell or install sprinkler systems, burglar alarms and fire extinguishers.
http://www.2theadvocate.com/stories/092704/new_firemarshal001.shtml

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AGENT eases building code fears
Yuma Sun - Yuma,AZ,USA
... The last time the city updated its residential building codes was in 2001.
At that time, the board examined the 1998 edition of the international code and made ...
http://yumasun.com/artman/publish/articles/story_13454.shtml

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EDITORIAL: October is National Fire Safety Month
Marshfield Mariner - Marshfield,MA,United States
... According to the National Fire Protection Association (NFPA), homes with smoke
alarms typically have a death rate that is 40 percent to 50 percent less than ...
http://www2.townonline.com/marshfield/opinion/view.bg?articleid=93409

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COMBUSTIBLE DUST. Any finely divided solid material 420 microns or smaller in
diameter (material passing a U.S. No. 40 standard sieve) that presents a fire
hazard or a deflagration hazard when dispersed and ignited in air.
Source: NFPA 1-2000 2-1.34

I'll see you in Laurel, MD this week. 
http://www.afaa.org/afaa/PDF/AdvFA_UCR_MD_Oct2004.pdf

Have fun!

Mike
mailto:mike@etnews.org

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ET NEWS JOURNAL 
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VOLTAGE DROP AND RMS CURRENT
----------------------------

On May 1, 2004 UL(r) changed some values that fire alarm system designers and plans
examiners use to determine circuit voltage drop. 20.4 volt is the assumed source
voltage, which represents the voltage available at the end of useful battery life,
in the words of UL(r).

Manufacturers are required to provide a standard voltage range of 16-33 volt
(nameplate) for all 24-volt notification appliances. Furthermore, UL(r) wants us
to use RMS current versus peak current in the volt-drop calculations. RMS, which
stands for Root Mean Square, represents the square root of the mean of the squares.
Say what?! Here's what it looks like mathematically:

Irms = Ipeak / sqrt2

"RMS current equals peak current divided by the square root of 2"

In the words of System Sensor "The higher RMS current draw inhibits over-design of
notification appliance circuits..."
Source: http://www.systemsensor.com/pdf/bulletins/voltage_drop.pdf

For example ...

 A notification appliance that draws .10 amp at 24 volt will draw more current,
 .15 amp at 16 volt:
 
 P = IE
  
 2.4 watt = .10 amp X 24 volt

 2.4 watt = I X 16 volt
 I = .15 amp
 
 To determine RMS current of this example: 
 
 Irms = Ipeak / sqrt2
 Irms = .15 amp / 1.414
 Irms = .106 amp

As you can see, RMS current is higher than peak current at nominal voltage
(24 volts), which takes into account the variable voltage and current that occur
in a notification appliance circuit.

In reality, manufacturers will use peak inrush current to determine RMS current
for a particular device. Be sure to read the manufacturer's specification in
determining minimum wire size based upon maximum volt-drop and use RMS current in
your calculations.

All of the work done by designers and plans examiners is to ensure a successful
acceptance test. During the acceptance test the inspector is not going to pass or
fail the system based upon volt-drop calculations or even wire size (with some exceptions)
but rather the inspector is going ask the installer to demonstrate that the device
located furthest from the power supply (source) is supplied with at least the minimum
nameplate voltage, 16 volt, when the NAC is energized.

======================================================================
JOB OPPORTUNITIES 
======================================================================

Place your "job opportunity" or "seeking employment" ad here. 
mailto:jobs@etnews.org

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FIRE ALARM CLASS SCHEDULE 
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------------------
October 5-8, 2004 Laurel, MD
------------------
Advanced Fire Alarm Seminar (NICET III & IV)
Understanding IBC Fire Alarm Requirements 
http://www.afaa.org/afaa/PDF/AdvFA_UCR_MD_Oct2004.pdf

------------------
October 12-15, 2004 Minneapolis, MN
------------------
Fire Alarm System Testing & Inspections Seminar
Intermediate Fire Alarm Seminar (NICET I & II) 
http://www.afaa.org/afaa/PDF/TI_IntFA_Minneapolis_Oct2004.pdf

------------------
October 21-22, 2004 Colorado Springs, CO
-----------------
Intermediate Fire Alarm Seminar (NICET I & II) 
http://www.afaa.org/afaa/PDF/IntFA_ColoradoSprings_Oct2004.pdf

------------------
October 26-28, 2004 Phoenix, AZ
------------------
Advanced Fire Alarm Seminar (NICET III & IV)
Fire Alarm Plan Review Seminar 
http://www.afaa.org/afaa/PDF/PR_ADV_Phoenix_Oct2004.pdf

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November 2-4, 2004 Oakland, CA
------------------
Fire Alarm Plan Review Seminar 
Advanced Fire Alarm Seminar (NICET III & IV) 
http://www.afaa.org/afaa/PDF/PR_AdvFA_Oakland_Nov2004.pdf

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November 9-11, 2004 Anchorage, AK
------------------
Fire Alarm Plan Review Seminar 
Advanced Fire Alarm Seminar (NICET III & IV) 
http://www.afaa.org/afaa/PDF/PR_IntFA_Anchorage_Nov2004.pdf

------------------
November 17-19, 2004 Buffalo, NY
------------------
Fire Alarm Plan Review Seminar 
Intermediate Fire Alarm Seminar (NICET I & II)
Contact Kristie Jesson mailto:kristiel@amherstalarm.com for more information

------------------
November 30-December 3, 2004 Portland, OR
------------------
Intermediate Fire Alarm Seminar (NICET I & II)
Understanding IBC Fire Alarm Requirements 
http://www.afaa.org/afaa/PDF/IntFA_UCR-IBC_Portland_Nov2004.pdf

------------------
December 14-16, 2004 Houston, TX
------------------
Fire Alarm System Testing & Inspections Seminar
Understanding IBC Fire Alarm Requirements 
http://www.afaa.org/afaa/PDF/PR_UCR-IBC_Houston_Dec2004.pdf

Contact me mailto:mikebaker@afaa.org to find out how your group can sponsor an AFAA seminar.

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COMMENTS AND ACKNOWLEDGEMENTS 
======================================================================

ET News is written nearly every week and almost always sent on Sunday.

Doug Hockinson built the PHP/MySQL ET News website -> http://phpvs.com

Purchase NICET Element Review Handbook online http://tinyurl.com/28ldd

Purchase NFPA, ICC, and more on line: http://www.etnews.org/index.php?s=461

Purchase a Moore-Wilson Report subscription: http://

Purchase new & used codes & standards on eBay http://tinyurl.com/36zzk

----------------------------------------------------------------------
Some information may be found within this email message that is reprinted with
permission from one or more of the following; NFPA 70 National Electrical Code (r),
NFPA 72(r) National Fire Alarm Code(r), NFPA 101(r) Life Safety Code(r),Copyright(c)
NFPA, Quincy, MA 02269.

This reprinted material is not the complete and official position of the NFPA on
the referenced subject, which is represented only by the standard in its entirety. 
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Some information may be found within this web site that is reprinted with permission from one or more of the following: NFPA 70 National Electrical Code®,NFPA 72® National Fire Alarm Code®, & NFPA 101® Life Safety Code®, Copyright© NFPA, Quincy, MA 02269.

This reprinted material is not the complete and official position of the NFPA on the referenced subject, which is represented only by the standard in its entirety.