HOME | Best Web Host | Question of the Week | Archived Questions | More Archived NEC Questions | Still More Archived Questions | Still More Archived Questions-2 | Still More Archived Questions-3 | Articles | Electrical Deficiencies | More Electrical Deficiencies | Electricians Tools | Online computers | Cybercorner | Electrician's License | Electronics Tutorials | Electricians' worksaving ideas | Electronic Theorems | Satellite Dish | Digital Cameras and Equipment | HTML Color Chart | Electronic Acronyms | Electronic Definitions | Electrician's Soldering Tutorial | Photovoltaic Power | Wind Power | Fire Alarm Basics | More Fire Alarm Info | Working with MC and EMT | Electricians' Color Code | Wiring Commercial Garages | Managing Your Emergency Lights | Lighting Design | Industrial Wiring | Wiring Ethernet | Residential Wiring | Low Voltage Wiring | PLC Overview | Electrical Troubleshooting Techniques | Using Loop Impedance Meter | Ten Common Grounding Errors |NEC and Low-Voltage Wiring | Raceway Protection and NEC | Working with Metal Raceway | Inductance and Characteristic Impedance | Understanding Capacitance | History of the Ethernet | Twisting Data Conductors | NEC Article 800, Communications Circuits | NEC Article 810, Radio and Television Equipment | NEC Article 820, Community Antenna and Radio Distribution Equipment | NEC Article 830, Network-Powered Broadband | Troubleshooting Submersible Well Pumps | Wiring Healthcare Facilities | First Edition National Electrical Code 1897 | Books for Electricians | Links




It is a great pleasure to announce the publication by McGraw-Hill of my new NEC 2011 guidebook. Reader feedback will be appreciated --



My second McGraw-Hill book for electricians, Troubleshooting and Repairing Commercial Electrical Equipment, now available from Amazon --






Now I've written a third McGraw-Hill book, out soon. The title is The Electricians's Trade Demystified. It is available for pre-order from Amazon. Click below --






You Can Pass Your Journeyman or Master Electrician's License Exam the First Time You Take It

Enroll in David Herres Electricians' Licensing Exam Course

(Details at electriciansexamprep.com )





MikeHolt.com

Wilderness Light Photography: Custom, commercial, landscape, nature, weddings, portraits, stock images by Judith Howcroft -- wildernesslightphotography.com


Order Satellite Dish Installation Tools Online --

Summit Source

Order Klein Electricians' Tools Online --

Klein Tools


Order Greenlee Electricians' Tools Online --


Order Ridgid Electricians' Tools Online --


Order Milwaukee Electricians' Tools Online --

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit

Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Since its founding in 1924, Milwaukee has focused on a single vision: to produce the best heavy-duty electric power tools and accessories available to professional user. Today, the Milwaukee name stands for the highest quality, durable and reliable professional tools money can buy. This deluxe 17 piece Electricians' Hole Saw Kit has the ultimate range of diameters available. The 12 diameters include: 5/8 inch, 3/4 inch, 7/8 inch, 1 inch, 1-1/8 inch, 1-1/4 inch, 1-3/8 inch, 1-1/2 inch, 1-3/4 inch, 2 inch, 2-1/2 inch, and 3 inch. The kit also includes arbor 49-56-7000 for hole saws up to 1-3/16 inch and arbor 49-56-7140 for hole saws 1-1/4 inch and larger. Additionally the kit has three pilot bits 49-56-8000 and an impact resistant plastic carrying case. The case is also sold separately as 48-55-0784. The hole saws in this kit are of the 6 teeth per inch design. Milwaukee 49-22-4085 17 Piece Deluxe Electricians' Hole Saw Kit Features: • Deluxe assortment of 12 hole saws, two arbors, and three pilot bits • Hole Saws: 5/8 in., 3/4 in., 7/8 in., 1 in., 1-1/8 in., 1-1/4 in., 1-3/8 in., 1-1/2 in., 1-3/4 in., 2 in., 2-1/2 in., 3 in.




Order Dewalt Tools Online --



Books for electricians --

Here is a selection of the most significant electricians' books available online today, at the best prices around. Clicking on any logo provides access to reviews and ratings by electricians. A good place to start is with the 2008 NEC Handbook, which contains the complete text of the current code plus extensive commentary, diagrams and illustrations. Other books of interest for the electrician are available as well.

This article originally appeared in Cabling Business Magazine--

Fire Alarm Basics


By David Herres


We take a look at fire alarm basics from the point of view of various code mandates plus some hardware and software elements-

For the cabling technician or electrician, fire alarm installation/maintenance is a highly lucrative recession proof line of work with numerous advantages. You get into an early stage of design and construction and so gain access to additional on-site cabling such as telephone and data. Moreover, it is possible to line up system maintenance and upgrades for years to come.

But fire alarm work is not for the faint hearted. It requires nerves of steel. Tremendous moral and legal issues are involved. In the event of a sudden catastrophic event, hundreds of lives may be on the line. Impeccable design accuracy and workmanship are required and the need for aggressively thorough maintenance cannot be overemphasized.

It is almost unthinkable that a fire alarm system would fail to go into alarm in the event of fire, without first sounding a trouble alert. But another danger existsâ the false alarm. This condition is very harmful. It is annoying to customers, particularly guests in a restaurant or hotel, and in an industrial setting it is costly in terms of labor to correct the problem and lost worker productivity. A far greater problem also exists. Repeated or even a single false alarm can lead employees to ignore a real alarm if fire should occur.

If you are contemplating entering the fire alarm field, the first thing to look at islicensing. This differs markedly from state to state and many large municipalities also have enacted regulatory legislation. Some states have a purely advisory voluntary licensing, which may be required by insurance companies, lending institutions or local building inspectors. Other states tightly regulate all phases of the work. Some jurisdictions enforce master electrician licensing for cabling and raceway installation and power hookup.

Whatever level of licensing is required, it should be regarded not as an ordeal but as a learning opportunity. One approach is to secure the contract and simultaneously hire a knowledgeable licensed individual or organization with whom you can work, thereby profiting from the job and also acquiring expertise. It will not be difficult to find a participating fire alarm professional if you provide the jobs.

There are several regulatory mandates that cover fire alarm design and installation. These do not apply to individual smoke detectors of the residential type, even if AC powered and wired for group operation--

  • Life Safety Code (NFPA 101): Specifies the occupancies that are required to have fire alarm systems.
  • National Fire Alarm Code (NFPA 72): Spells out system design requirements. Here we find operational protocols and minimum performance requirements, testing and maintenance procedures, also overall system design parameters including location and spacing of heads, pull stations and the like.
  • National Electrical Code (NFPA 70): In Article 760, Fire Alarm Systems, we find information on fire alarm system wiring including overcurrent protection and ampacity of power supply conductors to the control panel and zone wiring for initiating devices and indicating appliances such as horns and strobes. Additionally, NEC addresses other fire alarm functions including sprinkler waterflow, sprinkler supervisory functionality, fire door release, smoke doors and fan shutdown, LPG shutdown, elevator capture and release, only if these items are directly controlled by the fire alarm console. NEC Article 725, Class 1, Class 2 and Class 3 Remote Control, Signaling and Power-Limited Circuits covers wiring coming from the control panel. Power-limited circuits are defined in terms of voltage and available power and these have optional relaxed requirements for wiring methods and materials, insulation requirements, overcurrent protection, minimum wire sizes, derating factors and conduit fill.
  • Inspecting agencies such as Underwriters Laboratories list pull stations, horns, smoke detecting heads, control panels, batteries and similar equipment.

These codes provide minimum design and installation standards, but they are not to be construed as instruction manuals for untrained individuals. Where, then, to start? Let's assume you are a proficient electrician or cabling technician with good computer skills. An excellent introduction to fire alarm work can be obtained by reading some of the installation and user manuals provided by manufacturers. An existing system usually has the manual inside the control console door or posted nearby. These can be photocopied and studied at leisure. Simplex, Edwards and Honeywell are among the many manufacturers that provide excellent documentation, many available as Internet downloads. Manuals generally provide an overview of system capabilities followed by installation, programming and testing procedures.

Various makes are remarkably similar with variations primarily in the programming procedure.

The great advance in recent years has been the coming of addressable heads, which will be explained below. For a start, let's take a look at the principle parts of a fire alarm system. Once the underlying architecture is understood, installation, troubleshooting and repair become straightforward.

The control panel is the brains of the fire alarm system. From it emanate initiating device circuits and notification appliance circuits, described below.

The control panel is a user interface, which consists of a metal enclosure with transparent hinged front door. Without opening the door, a large alphanumeric display is visible, and it indicates which of three major states the system is in: Normal, Trouble or Alarm.

If the system is Normal, the alphanumeric display will so indicate, and the time and date may be displayed. Below the display are touch pads, which allow the user to respond as appropriate.

The whole essence of a fire alarm system is that while it is in Normal state, DC voltages (typically 24 volts, which permits the power-limited designation) are applied to the notification device circuits and to the indicating appliance circuits. At the end of each of these circuits is an end-of-line resistor, usually in the k-ohm range. The resistor is of great importance. At all times, when in Normal state, this resistance is seen by the control panel. If one of these circuits develops an open, short, or shunt to ground, the control panel will go into the Trouble mode. A buzzer will sound so that personnel in the immediate vicinity can respond and take whatever steps are required, but the entire building will not be disturbed.

If there were no end-of-line resistor, the control panel could not differentiate between Normal and open circuit. This is because the heads have not been activated and so have high impedance. Without the end of line resistor, the control panel would see an open, whether or not a break had developed in the line.

The resistor (which must, like all fire alarm components, be listed for the application) is normally placed in the base of the last initiating device or notification appliance in the circuit. (Canadian Code mandates a separate enclosure. In Europe, an end-of-line capacitor is used. One manufacturer in New Zealand has a control panel that can be programmed for either component.)

The end-of-line resistor will have different values for initiating device circuits and notification appliance circuits. Moreover, different manufacturers require different values, so it is important to use the proper resistor in new and repair work.

It is possible to work on a part of a circuit without disabling the whole thing. Just disconnect the segment you are going to work on and insert a temporary end-of-line resistor upstream. This operation will generate a Trouble state, which can be acknowledged. The control panel, once the Trouble state has been resolved, will automatically reset and go into a "system is Normal" state unless programmed not to do so.

It is also possible to place the end-of-line resistor inside the control panel at the circuit terminals, removing the conductors, but an easier alternative is to disable the circuit in question. To disable a circuit, follow the procedure in the installation manual. For a Simplex system, if the circuit is already in the Trouble state, press the trouble acknowledge button repeatedly, causing the alphanumeric display to scroll through the trouble reports. When the circuit you want to disable appears, press "disable", then press "enter". This allows you to work on a given circuit while the rest of the system is Normal and all other circuits are being monitored.

A circuit that is disabled enters the Trouble category. Since the disabled circuit is not able to report a fire, it is essential to have security or other personnel maintain a fire patrol until the circuit is re-enabled.

Furthermore, if there is a city tie, discussed below, it will be necessary to notify the monitoring agency, preferably in advance. This should be done anytime the system goes into the Trouble state.

The control panel also monitors itself internally. Each circuit has a printed circuit card, and if any of these develop an anomaly, or if the system loses AC power for a specified length of time, determined by programming, or if the DC voltage drops below a certain level, the system will enter the Trouble state.

If the system enters the Alarm state, it should immediately be acknowledged. This will cause the system to record in its history, (which can be retrieved later) the exact time of such acknowledgement. Performing this step does not silence the alarms, which may be very loud.

In the event of Alarm, the procedure is to have personnel go to the site of the initiating device and ascertain whether there is a fire or other dangerous situation Once it has been determined that it is a false alarm (caused by steam, someone smoking under a head, accumulation of dust within the head, etc.) or if it is a fire, and if so the fire has been contained, it is permissible to silence the alarm. After the fire has been put out and the head(s) in question cleaned or replaced, the alarm should be silenced, then the control panel reset so that it can return to the Normal state and resume protective function.

Older systems did not have addressable heads. Currently, addressable head systems are employed, and older systems are reconfigured to be addressable. Nonaddressable (so-called "legacy") systems indicated at the alphanumeric display only which zone was causing the system to go into Alarm or Trouble. Then the heads, with normally blinking LEDs, would have to be surveyed. The one causing the alarm would have its LED on steady. Or the pull stations would have to be examined to determine which one had been activated.

With addressable initiating devices, each head is assigned a unique numerical address, which is also entered into the control panel along with a name, such as "Main Office Back Room". Assigning an address is accomplished by adjusting slide switches in the base of each head. Then, in the event of an alarm, the exact head or pull station will be shown on the alphanumeric display.

A frequent upgrade these days is to convert a legacy fire alarm system to one with addressable heads. The existing control panel is retained with new cards installed. Existing raceway and in some cases original wiring is kept. New addressable heads, bases and up-to-date notification appliances with strobe lights for hearing impaired individuals are introduced.

A contemporary fire alarm system offers a vast amount of capability. A city tie modem can be put in to meet current codes. It involves two redundant telephone lines to a remote monitoring station, which is notified in case of Alarm or Trouble. Test calls are automatically made on a scheduled basis and if a call cannot be completed, the system enters the Trouble mode until corrections are made.

Fire doors, normally held open by magnets, close upon Alarm or system failure. If battery and AC power were to simultaneously fail rendering the system totally inert, fire doors throughout the building would swing shut.

Another important feature is elevator capture and return.

If the building is equipped with sprinklers, every sprinkler head becomes in effect an initiating device. This is because water flow in the sprinkler system causes the system to go into the Alarm state. For dry sprinkler systems, where piping and heads are filled with air and water is released when air pressure (normally set for 55 psi) drops below a certain level (typically 33 psi) an intermediate air pressure (38 psi) triggers a Trouble state. Workers can add air, repair a leak or disable a branch by closing the main water valve until repairs can be made. This saves flooding the sprinkler system, which would have to be drained.

If water flow occurs, the alarms go off. Unlike in the case of activated heads or pull stations, the alarm cannot be silenced until the main water valve is closed. This is to limit water damage in case of broken sprinkler pipe.

Before a new fire alarm can be put into service, it needs to be programmed. This is accomplished by pressing touch pads on the control panel in proper combinations and sequence. Procedures for various makes and models are given in the installation manuals. Moreover, passwords can be programmed into the system permitting various levels of access so that different individuals can perform designated tasks.

If something goes radically wrong and you can't silence an alarm or acknowledge a trouble, there is one final recourse. After verifying no fire, unhook the battery (first), then unplug the AC connector or open the circuit breaker at the service or feeder panel. This will disable the entire system. Since there is no fire protection, it is necessary to initiate a fire patrol and inform the monitoring agency and the insurance company to certify that fire insurance is not voided.

All of this is exacting work and requires considerable study and on the job experience to become proficient, but it is certainly an effective way to deal with any economic downturn.
--END--

Low Voltage, Telecom, Fire Alarm Books --



This site is created and conducted By David Herres, NH Master Electrician License #11335M

E-mail: David@electriciansparadise.com


HOME | Best Web Host | Question of the Week | Archived Questions | More Archived NEC Questions | Still More Archived Questions | Still More Archived Questions-2 | Still More Archived Questions-3 | Articles | Electrical Deficiencies | More Electrical Deficiencies | Electricians Tools | Online computers | Cybercorner | Electrician's License | Electronics Tutorials | Electricians' worksaving ideas | Electronic Theorems | Satellite Dish | Digital Cameras and Equipment | HTML Color Chart | Electronic Acronyms | Electronic Definitions | Electrician's Soldering Tutorial | Photovoltaic Power | Wind Power | Fire Alarm Basics | More Fire Alarm Info | Working with MC and EMT | Electricians' Color Code | Wiring Commercial Garages | Managing Your Emergency Lights | Lighting Design | Industrial Wiring | Wiring Ethernet | Residential Wiring | Low Voltage Wiring | PLC Overview | Electrical Troubleshooting Techniques | Using Loop Impedance Meter | Ten Common Grounding Errors |NEC and Low-Voltage Wiring | Raceway Protection and NEC | Working with Metal Raceway | Inductance and Characteristic Impedance | Understanding Capacitance | History of the Ethernet | Twisting Data Conductors | NEC Article 800, Communications Circuits | NEC Article 810, Radio and Television Equipment | NEC Article 820, Community Antenna and Radio Distribution Equipment | NEC Article 830, Network-Powered Broadband | Troubleshooting Submersible Well Pumps | Wiring Healthcare Facilities | First Edition National Electrical Code 1897 | Books for Electricians | Links