[Make-wifi-fast] 2.4Ghz hybrid wiring for nest protects

Bob McMahon bob.mcmahon at broadcom.com
Tue May 18 19:32:04 EDT 2021

Yeah, this whole thread should start with a disclaimer of *no
responsibility nor liability for any opinions expressed*. I'm not a lawyer
and not sure the best way to write such disclaimers, but I fully understand
the seriousness of fire alerting and that a WiFi discussion group is not a
place to go for anything more than discussion and opinions.

As some background, and way off topic for sure, I called the local fire
department and they said there is no current requirement for a floor to
floor alerting system on older buildings. I then asked if they would have
their kids live in such a building and the answer was, "I can't answer
that." And any other following question I had was "google it" because "we,
the fire department, don't want to take liability for something we can't
affect." I also spoke with a person who runs a fire consulting business and
he said not having alerting on the egress escapes was not safe,
particularly for higher level floors.

I found that a professionally installed alerting system would cost $60K to
$100K. This is just alerting, not suppression. Needless to say, the HOA
doesn't have such funds. Each unit has a few chirp alarms which seems to be
sufficient for the fire department w/respect to them not hindering "real
estate transactions" because real estate business is serious too. The fire
dept would get crushed politically if they imposed $100K bills on people
trying to meet their rents. Note: they will get involved when a building
has major improvements but, until then, they're basically trying to avoid
any kind of liability and they only get involved after the building
department asks them too. In other words, the building is not going to be
honestly evaluated for fire safety by anyone in a position of expertise and
responsibility until it undergoes a major remodel - which will force most
people out. I find reality usually is what it is vs what I'd like it to be.

NO RESPONSIBILITY AND NO LIABILITY applies to all from my perspective.

And please don't think I'd trust anyone here for such a system that affects
human life. Not meaning to be disparaging to anyone.


On Tue, May 18, 2021 at 2:57 PM Jannie Hanekom <jannie at hanekom.net> wrote:

> (This contribution is probably drifting a bit off topic significantly.
> Apologies for that.)
> I have to acknowledge: As someone who lacks the expert-level technical
> knowledge most contributors on this list have, what I say doesn’t carry
> much weight.  I’m here mostly because I enjoy the content.  But, I have a
> few concerns I’d like to raise, mostly related to safety…
>    - Fire is a serious matter.  As well-intentioned as it may be, using a
>    prosumer-grade fire alerting product in an commercial or high-density
>    residential setting may not be appropriate.  It’s one thing for the
>    occupant of a residential unit to install their own device.  It’s something
>    quite different to use it as part of the services a building offers to its
>    tenants.
>    - Creating a building-sized 2.4Ghz antenna sounds like an interesting
>    experiment, but wouldn’t the noise-floor being prohibitively high?
>    - Supporting such an environment on your day off would be a
>    challenge.  That’s important considering the functionality the solution has
>    to deliver.
>    - Something I’ve learnt about loops and other redundant systems is
>    that their reliability benefits are only as good as the processes that
>    monitor them for failures.  Passive cable is really hard to monitor.
> Then, as someone occasionally involved in deployments of commercial
> off-the-shelf solutions through my $dayjob, I’d argue that the
> “traditional” route of installing a bunch of CAT6 and one or more APs per
> unit (if the solution **had** to be Nest Protects) would likely score
> higher on availability, performance and supportability.  (If you’re talking
> Zigbee not WiFi then I’m even further out of my depth, but I’d argue the
> same points still apply.)
> Jannie
> *Van:* Make-wifi-fast <make-wifi-fast-bounces at lists.bufferbloat.net> *Namens
> *Bob McMahon via Make-wifi-fast
> *Gestuur:* Maandag 17 Mei 2021 20:09
> *Aan:* Make-Wifi-fast <make-wifi-fast at lists.bufferbloat.net>
> *Onderwerp:* [Make-wifi-fast] 2.4Ghz hybrid wiring for nest protects
> Hi All,
> There is a historic building that has 5 floors and no fire alerting
> associated with the rear fire escape ladder. I'm considering installing
> nest protects in each unit near the rear egress to alert of the fire escape
> is compromised by fire. My guess is floor to floor wireless communications
> may not work too well.
> I'm thinking about cleaning up the communications runs in the rear of the
> building. The cable company did a shoddy job of hanging cable for TV
> services in the 80s. It seems a good time to add communications conduit and
> run more modern cabling.
> As part of this, I'm considering running LMR 600 cabling on the exterior
> brick wall to act as 2.4Ghz communications wave guides. I was thinking make
> a loop but break the loop at each floor with a 2.4Ghz wilkinson power
> divider
> <https://www.pasternack.com/2-way-n-wilkinson-power-divider-690-mhz-2.7-ghz-10-watts-pe2092-p.aspx?utm_source=google&utm_medium=cpc&adpos=&scid=scplpP74039&sc_intid=P74039&gclid=CjwKCAjwqIiFBhAHEiwANg9szk1JG2oJufz2G2Hylc6oOgOSl-tBN5O39Kn2T1pHV4g8_r8AnkFA7xoCFhUQAvD_BwE>.
> Then bore a hole into each unit and install a 2.4Ghz patch antenna
> <https://www.l-com.com/wireless-antenna-24-ghz-8-dbi-round-patch-antennas>
> pm each rear interior wall. Each unit would then install a Nest protect on
> the ceiling from the patch antenna. The ring or loop topology I think gives
> a bit of redundancy.
> Thoughts on if this would achieve the goals of supporting nest protect
> communications for such a building?
> Bob

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