Coax & cat 5 pull and web connected appliances

[Karl W4KRL]

Last May we had a new high tech heat pump installed. In addition to the VVVF
blower control it has a web connected thermostat. I can control the system
from my cell phone anywhere. Sort of like Gaslight without having to go into
the attic.

 

Last week the system started sending e-mail saying that the indoor blower
motor was generating alarm #201. Fortunately we still had heat even though
the system cried for help two or three times a day.

 

The repairman just left. He found that the thermostat line was tie-wrapped
to the 230VAC line feeding the blower and EMI from the inverter picked up by
the thermostat line was confusing the blower control board. He separated the
lines and we will see what happens.

 

For your interest, here is very typical language from rapid transit car
specifications.

 

Circuit Separation

1.     Circuits in wire runs shall be physically separated to prevent
induction of signals between adjacent wires or runs and reduce the
possibility of unsafe conditions, interference, or equipment damage.

2.     Conductors or bundles of conductors of a voltage system (e.g., low
voltage distribution network (LVDN) voltage, 120 Vac, 240 Vac, 650 Vdc)
shall be segregated and positively separated from conductors of other
voltage systems.

a)     Where a raceway, duct, junction box or enclosure is divided into two
or more distinct areas by metallic partitions, each area may be considered
separately in the application of this rule.

b)     Where it is impossible to avoid having wires at different voltages in
the same equipment enclosure, the wires shall be physically separated and
bundled separately. All wires within the enclosure shall be protected to the
highest voltage in the enclosure.

c)     Wires connected to transient-generating apparatus, such as
unsuppressed contactor coils, shall be routed to prevent coupling to wires
carrying signals to, from, or between other circuits, such as No Motion, cab
signal, or communication circuits. In cases in which adequate physical
separation is impossible, shielded wire shall be used for all conductors
involved.

d)     In addition to the general circuit separation in wire runs required
in Section 505 A.2.a., the following major circuit groups shall not be
harnessed or bundled together, shall not run in the same conduit, and shall
be physically separated and secured in enclosures, wire ducts, junction
boxes, or other wire routing devices:

                                          i.    ACSES/ATC/ATS/Cab Signal
circuits;

                                         ii.    Third Rail circuits;

                                        iii.    Overhead catenary circuits;

                                        iv.    AC circuits;

                                         v.    Communication circuits;

                                        vi.    Battery voltage level
circuits; and

                                                           vii.
Semiconductor gating voltage level circuits.

 

73, Karl W4KRL

 

From: On Behalf Of Alex Fraser
Sent: Thursday, January 23, 2014 3:48 PM
To: tacos at amrad.org
Subject: Coax & cat 5 pull

 

I'm running a new hunk of coax to my cable box.  I thought I'd run some cat
5 Ethernet cable over in the same pull, so I can stream videos from the net.
The coax is I believe RG6 with a copper shield and also a foil shield.  They
will be pretty close together, even touching.   Will there be interference
problems?  



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