Re: INSTEON over CAT5; was Re: What can I replace this latching relay system with?

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Mon, 31 Jul 2006 01:32:18 -0400, Marc_F_Hult
<MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote in message
<dj2rc25pqm14tthqmnu46kmg6ce5pe5hck@xxxxxxx>:

>In response to a recent comp.home.automation question on how to retrofit
>wiring to provide dimmed lighting and (preferably) provide automation to a
>house that uses 1950's vintage relay-controlled lighting  (Subject: "What
>can I replace this latching relay system with?"), I  bread-boarded a
>concept using INSTEON power line control (PLC) devices that I had
>previously tested with X-10 but didn't end up using.
>
>The original poster's challenge is that the existing wiring to the wall
>switches is suitable only for low voltage and installing new wiring is not
>acceptable. The low voltage switches on the wall control latching relays
>in the ceiling that switch the AC power to the ceiling-mounted lights. The
>AC wiring to the ceiling lights is not individually "home-runned" to the
>entrance panel, so centralized dimmers would require re-wiring the AC
>wiring which is also not acceptable.
>
>The circuit below solves these issues and provides for both dimming and
>home automation control of the lighting using the existing wire
>infrastructure.  It transmits powerline control signals and sufficient AC
>power to power an INSTEON device for input and signaling purposes only
>over the existing low voltage wiring from the AC power and ceiling lamp to
>the wall switch.
>
>The wall-mounted INSTEON dimmer(SW1) sends dimming and other signals to
>INSTEON dimmer SW2 which in turn controls the light. INSTEON SW2 also
>repeats the signal received ensuring that it is available in the AC wiring
>throughout the house for conventional home automation control.
>
>I tested this arrangement 'on the bench' using both ~200 feet of CAT5 wire
>and ~200 feet of 24-gauge non-twisted telephone wire as the interconnect.
>The gauge of the wire needs to be sufficient for the load. Current through
>the nominal 24AC control line was about 200mA with an INSTEON ICON switch
>(relay) connected for SW1.
>
>One could also control a small load on the isolated INSTEON device by
>using sufficiently large transformers and interconnecting wires of
>appropriate gauge and installation.
>
>
>120VAC                   C1                     C3
> Hot  ------+----------+-||-+                 +-||-+
>(black )    |          |    |                 |    |  (black)
>      INSTEON(red)     +    +-->>------<<-----+    + ---+
>       SW2--+ ---+     S || S     low         S || S  INSTEON
>            |    |  T1 S || S    voltage   T2 S || S  SW1(red)-Not
>            |   Load   S || S    wiring       S || S    | connected
>            |    |     |    +--->>-----<<-----+    +----+
>AC Neutral--+----+-----+    |                 |    |  (white)
>(white)                |    |                 +-||-+
>                       +-||-+                  C4
>                         C2
>
>Where:
>
> T1, T2 = UL-listed Class 2, 24volt, 20VA "doorbell" transformers
> C1-C4 = 0.22ufd 250VAC mylar capacitors
> SW1 and SW2 are INSTEON switches or dimmers. SW2 must be suitable for
>	the load it controls. There is no load connected to  SW1.
>
>In my bread-boarded test, I used capacitors removed from an X-10 PRO
>filter unit where they are used to bypass the inductors.
>
>THIS IS POSTED WITH NO CLAIM AS TO ITS SUITABILITY FOR ANY PARTICULAR
>INSTALLATION OR APPLICATION. DANGEROUA VOLATGES ARE PRESENT THAT COULD
>PRESENT A SHOCK (ELECTROCUTION) OR FIRE HAZARD. As with all home wiring,
>inspection and approval of the authority having jurisdiction is generally
>required by local ordinance -- and common sense. In other words, I AM NOT
>RESPONSIBLE FOR ANY LIABILITY ARISING FROM ITS USE OR OTHER APPLICATION.
>
>I'll post some pictures later to
>www.ECOntrol.org/INSTEON0verCAT5.htm )

It is useful and perhaps necessary to explain the purpose of the two
transformers, T1 and T2 in part because many folks may think that their
sole function is voltage conversion.

They also serve as current-limiting devices which is the function that
protects the wiring from short circuits or other high current conditions.
They also provide galvanic isolation and eliminate the ground connection.

The UL-listed, Class-2 transformers in my bench test setup are rated at
20VA (volt-amp = watts) which is greater than the power limit of the
present form of Power Over Ethernet (POE) of 15 watts. The present version
uses two conductors per leg; a proposed version of POE will up the power
rating to 30 watts or more. The regulatory considerations are more complex
than the physics, and I will not deal with the former here. Suffice it to
say for now that the 20VA rating of the transformers used is appropriate
for the 18 gauge (AWG) wiring commonly used for doorbells and other
common-low-voltage residential applications. And that a smaller transformer
with a lower VA rating (also readily available at Big-Box home improvement
centers) would be more protective for Cat-5 .

HTH ... Marc
Marc_F_Hult
www.ECOntrol.org