This trade depends on National Electrical Code compliance, especially where it involves device placement and connectivity. Knowing how to install initiation and notification appliance devices is integral to the fire safety mission, and electrical contractors (ECs) who routinely work in this low-voltage segment know all about this.
One question that arises among apprentices and entry-level journeymen is, “How high off the floor and how close to the door do I install these devices?” Knowing the correct answer can mean the difference between a green or red sticker on final inspection.
Although installing to Code is important, the authority having jurisdiction (AHJ) must also be on board with whatever the EC does. This is why fire alarm technicians must turn in a submittal package to the local building department for examination and approval. This package usually consists of one or more blueprints that show the position of every device, in addition to product specification sheets, voltage drop and current calculations and other information.
The bottom line is, before the job can commence, the plans examiner must approve the submittal package that the EC or subcontractor provides. Only then is work legally allowed to start.
In order to have reliable, dependable fire alarm operation—whether the building occupants are in California or Florida—standardization using NFPA 72, 101 and 70 is a must. The code not only describes where to install these devices, but also how high and how close to known building features they need to be.
In the remainder of this story we’ll discuss code-compliant device placement in an effort to illustrate the most common practices used in the fire alarm industry. But remember, installing to the code is only part of the magic. The other part is getting the AHJ to approve it.
Initiating device placement
There are essentially two types of initiating devices used in a typical fire alarm system: automatic and manual.
Typical automatic devices include spot-type smoke detectors, rate-of-rise heat sensors, fixed-temperature sensors, photoelectric smoke detectors, sprinkler heads and duct-type smoke detectors.
Manual activation is commonly accomplished using a manual fire pull, and automatic detection happens without human intervention. NFPA 72, also called the National Fire Alarm Code (NFAC), is the primary document used when an engineer designs, and an EC or fire alarm technician installs, a fire alarm system.
The other code that ECs and low-voltage installation firms have to deal with is that of NFPA 101, also known as Life Safety Code. This code deals with the issue of where and when to install fire protection, whereas 72 deals with how it is done. NFPA 70, or the NEC, provides direction when it comes to the installation of the cable, such as the voltage rating of the insulation or how that cable is hung in specific types of environments.
Placement of manual pulls
The manual fire pull is one of the most commonly required fire actuation devices found on any job you perform. Whether the facility is classified as industrial (F), business (B), institutional (I), mercantile (M), educational (E) or something else other than residential, there’s almost always going to be at least one manual pull on the job.
According to Section 188.8.131.52.2, NFPA 72, 2007 Edition, there must be at least one manual pull in a protected-premises fire alarm system. Section 5.13.5, NFPA 72, also requires that manual pulls be easily seen and readily available for use. The physical path to each one also must be kept clear of obstructions so that anyone, disabled or not, has ready access at a moment’s notice.
Manual pulls are to be installed at each point of exit discharge so that someone who witnesses a fire in progress can warn others still inside the building as they exit. The distance from an exit door to a manual pull must not exceed 5 feet. In addition, manual pulls often will be placed on each floor near each stairway exit (see section 5.13.6, NFPA 72, 2007, “Manual fire alarm boxes shall be located within 5 feet of the exit doorway opening at each exit on each floor.”) And when there’s a group of doors that span a distance of 40 feet or more, the code calls for a manual pull on each side of the grouping.
Section 5.13.8, NFPA 72, 2007 Edition, also stipulates that, in larger buildings, manual pulls must be positioned so there is one within every 200 feet: “Additional manual fire alarm boxes shall be provided so that the travel distance to the nearest fire alarm box will not be in excess of 200 feet measured horizontally on the same floor.”
Manual pull mounting height
Another important aspect associated with device placement involves the height at which it must be mounted. In this case, height is measured from the floor to the “operable part of each manual fire alarm box.” According to Section 5.13.4 of NFPA 72, 2007 Edition, mounting height must be between 3½ and 4½ feet from floor to handle.
Since the advent of the Americans With Disabilities Act (ADA), the National Fire Protection Association, Underwriters Laboratories (UL) and other codes- and standards-making bodies have harmonized their guidelines with federal ADA rules.
Section 4.2.5 of the ADA states, “If the clear floor space only allows forward approach to an object, the maximum high forward reach allowed shall be 48 inches. The minimum low forward reach is 15 inches.”
When considering side reach, the mounting height can be up to 54 inches to the handle.
Section 4.2.6 of the ADA states, “If the clear floor space allows parallel approach by a person in a wheelchair, the maximum high side reach allowed shall be 54 inches and the low side reach shall be no less than 9 inches above the floor.”
Audible and visual notification
There are two operating modes on which NFPA 72 provides direction: public and private.
According to 184.108.40.206, NFPA 72, 2007 Edition, Private Operating Mode is “[a]udible or visual signaling only to those persons directly concerned with the implementation and direction of emergency action initiation and procedure in the area protected by the fire alarm system.”
Section 220.127.116.11 defines Public Operating Mode as “[a]udible or visible signaling to occupants or inhabitants of the area protected by the fire alarm system.”
The first consideration is how loud the audible portion of a notification appliance circuit (NAC) device should be and the point at which it is either too soft or too loud. The other issue pertains to the visual aspects of signaling devices. This portion of the equation deals with the candela rating of the visual portion of the NAC device.
The output of the audible portion is mandated by Section 18.104.22.168 to be at least 105 decibels (dB). The maximum sound pressure level allowable at the minimum distance when combining ambient noise with that of the notification appliance devices should not exceed 110 dB. Sections 22.214.171.124 through 126.96.36.199 provide additional direction on the how and why of audibility.
When used in public mode, NAC devices should be rated 15 dB above the average ambient noise level, 5 dB above the maximum sound level with duration of 60 seconds or whichever is greater.
Section 188.8.131.52, NFPA 72, 2007 Edition, says private-mode NAC devices should be rated 10 dB over “the average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds, whichever is greater.”
Wall-mounted NAC devices should be placed no less than 80 inches and no more than 96 inches above floor level. However, when the height of a ceiling prevents this, Section 184.108.40.206, NFPA 72, 2007, says to mount them within 6 inches of the ceiling.
When it becomes necessary to mount your NAC devices below 80 inches, the code says you must reduce the room size by twice the difference between the code-specified 80 inches and the actual distance used in your calculations.
NFPA 72 also offers an alternate method of determining mounting height using a performance-based method.
For information on this aspect of the job, see Section 220.127.116.11, NFPA 72, 2007.
Smoke detector placement
Automatic smoke detector placement is another important aspect of a fire alarm installation. Unless every smoke detector is placed properly, false alarm, or even no alarms, can occur. Either way, the client suffers, and the low-voltage contractor looks bad in the process.
The most common type of smoke detector used in residential and commercial settings is the spot-type detector. According to Section 18.104.22.168, NFPA 72, 2007 Edition, spot-type smoke detectors can be mounted either on the side wall or ceiling. When using the side wall, mount the device no closer than 4 inches from the ceiling.
The maximum distance is 12 inches. The distance from detector to side wall when mounting the same smoke detector on a ceiling is the same 4 inches. Ceiling-mounted units also must be placed no closer than 4 inches from a side wall.
Spacing between smoke detectors is likewise important. On a smooth ceiling, the common distance between each smoke detector is 30 feet. According to Section 22.214.171.124.3.5, all points on a smooth ceiling should have a smoke detector within 0.7 times the selected spacing or 21 feet.
Not all ceilings are smooth; thus, the spacing between smoke detectors will vary. To ensure optimum performance and compliance, refer to Chapter 5 of NFPA 72, 2007 Edition, for a specific situation. Read also Codes & Standards, page 140.
Space and placement both matter when planning your fire alarm package. Thorough preparation often leads to a successful installation.
COLOMBO is a 32-year veteran in the security and life safety markets. He currently is director with FireNetOnline.com and a nationally recognized trade journalist located in East Canton, Ohio.