My name is Chris Kalivas, I am a Code Enforcement Officer for NYS and I thank you for the opportunity to present my concerns to the NYS Code Committee. It has come to my attention that in the next code cycle NY will adopt the 2015 IRC code R314, the interconnection of residential smoke alarms. I envisioned one day for lack of a better economical solution to interconnect existing homes the code would accept wireless transmissions. That’s a good thing because when it's not possible to hardwire an interconnection, any attempt to potentially increase the safety of a home is better. However the IRC 2015 appears to state that it would also apply to all new construction. If wireless is adopted the way it is written then I strongly believe if the code does not require the installation of a third signal wire while the walls are open during new construction, then it will be doing a serious injustice to future homeowners and may even put future lives at risk. When the wireless becomes problematic, and ample precedence shows that this is possible, then the homeowner will have lost the only opportunity to create the best most secure connection that we have today.
A significant problem for Radio Wireless Alarms is to overcome interference from all the radio signals transmitted from broadcast AM/FM radio and television, as well as most of today's new electronic devices: audio and security systems, amateur radios, phones, game stations florescent and led lighting systems, appliances, watering systems, door locks, thermostats, along with many other electrical devices and equipment. It seems that everything today, (and so many more devices in the future), is moving toward being wireless, and could potentially degrade the reliability of critical radio intercommunications, which has been the subject of numerous studies that clearly document this.
Another significant disadvantage of using through-the-air radio transmissions inside a structure is the unpredictable nature of “capacitive absorption” of the radio signal power being radiated by the transmitter into surrounding objects, which is caused by the structure itself and all the things in it, all of which are totally unpredictable and vary from structure to structure. Floors, walls, and ceilings, especially those painted before 1970 with lead paint, which, even in small amounts, is a notorious barrier to low level wireless signals. Wireless smoke alarm user manuals all have additional warnings to avoid many other obstructions such as ductwork, drop ceilings, metal studs, and to test interconnections with metal doors open and closed. They also recommend testing the interconnection of the wireless alarms at least once a week to determine whether there are any physical sources of interference preventing communication, and that radio paths have not been disrupted by simply moving furniture.
However the most compelling reason why Radio Wireless Alarms should not be used as a reliable interconnection is presented within the conclusions of many Government, University and Military studies as attached to this document. These studies clearly show that the very things from which life must be protected, specifically fire and smoke, can be the very thing that degrades the radio signals used by Wireless Alarms and may disrupt their ability to interconnect. Potentially the most devastating cause of radio interference is the well documented effects of “wave-bending” and “floating insertion loss”, caused by the clouds of ionized gasses, both hot and cool, caused by fires that are trapped within the structure. This is the very same effect suffered by orbiting spacecraft returning to earth encased in ionized atmospheric gasses, rendering them incapable of radio communications. All of these characteristics will severely limit the range of a transmitter, making them highly unreliable and unsuitable for a fire safety application.
If NYS Code Committee adopts the IRC 2015 as written, and houses are permitted to use wireless alarms in new residential buildings then how is a CEO to know that they all fully work.
As a building inspector of course I will go to every location to verify that each alarm goes off but without using a network antenna analyzer I have no way of knowing if the obstructions from the structure of the house have degraded a signal by 50% or 99%. If there is no access to that information no one can have any assurance that the next test will work, or any assurance that the system will work when the new homeowners move in, or that the communication between the alarms has been disrupted because their china closet absorbed or scattered what's left of the transmission. With radio linked alarms they go to bed every night unaware that the cellar smoke alarm may not communicate with the bedroom smoke alarms.
Or even if a test with a network antenna analyzer showed 75% degradation of a signal, should we consider that OK? When we lose our router signal for our computer, if we drop a cell signal, or have a glitch with one of our wireless devices, it's no big deal. The simple and undeniable fact is that there are too many documented and proven issues that can effect through-the-air transmissions. With all these factors, each working together to degrade signal strength, when communication is a matter of life and death, wireless communications will always be unpredictable, and that makes it unacceptable for this venue.
Technicians who install and diagnose problems for smart homes in NYC will tell you that when there are problems with the wireless devices in the system, the Spectrum and Network Analyzers are their most important tools. They will always say that whenever possible they would always prefer and trust the hardwired device. They, along with most wireless manufacturer’s user manuals suggest to correct these problems by adding more wireless devices to direct the signal around these problems However walls and ceilings are now finished so the additional alarms added to the system become battery powered only. This situation should not be allowed to exist.
In short, how much money are you really saving with wireless? It's not much of a savings compared to the overall cost of the project and life safety may be compromised.
- It's a documented and undeniable fact that wireless signals are degraded when traveling through obstructions such as walls, floors, ceilings, furniture etc. An RF transmission traveling through a wall on an angle could be adsorbed, scattered and weakened 10 times more then a signal traveling perpendicular through the wall.
- All Wireless signals are subject to interference from the endless varieties of wireless devices of a very wide range of radio frequencies. There will always be many cases of false alarms and times where Radio Frequency Interference rendered wireless alarms useless without occupants knowing.
- All Wireless signals are subject to some degree of degradation from various types of atmospheric ionization due to Fire and Smoke. Most studies to date were conducted to understand and find solutions to the effect of fire and smoke with the communications between fire fighters battling outdoor fires. I feel certain that as wireless alarms are more widely used in residential structures we will see in the future more studies on the effects of fire and smoke inside structures that will substantiate all of the previous data acknowledging the problems with radio communication inside a structure impaired with hot ionized gasses.
We honor our brave fire fighters who put their lives on the line while protecting our lives and properties. Sadly it is tragedies like these that help us develop better and safer codes.
When I became a building inspector I immediately saw the need for the interoperability of smoke alarms in existing homes. However after much research I came to understand the serious limitations of wireless interconnections.
In conclusion I do not believe through-the-air communication should be allowed in residential dwellings or any structures where there are sleeping areas. In my professional opinion I believe The NYS Code should remain unchanged and not allow the ICC option of using wireless.
Radio Experiments With Fire - Jonathan Boan, Student Member, IEEE File Name hdl_43372.pdf
The experiments described in this paper have shown that when naturally occurring plant life is burnt it has a significant effect upon radio propagation.
The Signal Propagation Effects on IEEE 802.15.4 Radio Link in Fire Environment
Consistent results were observed in deterioration in signal strength and link quality parameters over the distance for the considered small fire environment.
RAY TRACING RADIO WAVES IN WILDFIRE ENVIRONMENTS University of Botswana & James Cook University, CONCLUSION Radio waves (150–3000MHz frequency range) that propagate in a plume of an intense wildfire were significantly affected by temperature or refractive index gradients. http://www.jpier.org/PIER/pier67/06.06082302.Mphale.H.pdf
Radio Propagation in Fire Environments University of Western Australia
Radio propagation through a fire is disrupted resulting in a change in signal characteristics which, has been verified over a number of fires of different size and fuel.
Naval Research Laboratory NRL/MR/6180--98-8156
The Effects of a Fire on Radio Wave Transmissions
STRUCTURE COMMUNICATIONS ISSUES
Material of the Effect of Fire Fronts on V/UHF Radio Communications
Conclusions Fire fronts do have an effect on the attenuation of radio signals. WIT.3028.001.0059