X10 Community Forum
🔌General Home Automation => Automating Your House => Topic started by: mike l on December 11, 2005, 01:56:02 PM
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Hi,
At our family cottage (in a rural, colder
climate) - I have a portable heater
connected to an SR227 receptacle module. We
use it to call ahead and turn the heat on
during the winter months. Works great.
Here's the problem. The electrical boxes in
this cottage are old - and under-sized. As
such, the SR227 isn't a great option
elsewhere in the house (it was a real pain
to install ONE SR227, let alone four more).
I'd have to replace electrical boxes - and
I'm worried about some of the retrofit
insulation falling out of the wall when I do
so (again, this is an older cabin in a rural
area).
Instead, I'd like to use the AM486/66 to
remotely activate three additional portable
heaters (we turn them on when we're driving
up to the cottage). I noticed it's rated
for 15 amps (which is fine) - but only for
500 Watts. These heaters are 1500 watts.
From Brian H's response to Maynard's
question - I get the impression this might
be fine. I'm fairly handy, but not an
electrician. If someone can explain, I'd
appreciate it.
Cheers,
Mike
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I think I found an answer. Can someone
confirm if this is correct?
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Question
The rating label on X10’s Appliance Module
says that it is rated at 15 Amps but that it
can be used for controlling lamps up to 500
Watts. I have some knowledge of electrical
theory and know that Ohm’s Law states that
Watts = Volts x Amps. Therefore as 120 x 15
= 1800, surely the Appliance Module should
be able to control up to 1800 Watts. Please
will you explain this discrepancy?
Answer
Your understanding of Ohm’s Law is correct.
The Appliance Module is rated at 15 Amps
resistive. That means it will control up to
1800 Watts of resistive type loads such as
heaters, coffee pots, electric blankets,
crock pots etc. However, a lamp is a
different story. When an incandescent lamp
is first turned on it’s filament is cold and
as you may also be aware, resistance
increases with temperature. The resistance
of the filament is therefore initially lower
than it is when the bulb is hot (up to 10
times lower). A 500 Watt lamp consumes about
4 Amps of current but the "inrush" current
when the bulb is cold can be up to 10 times
higher than this. The Appliance Module is
designed to handle this inrush current but
the contacts of the relay in the Appliance
Module would weld themselves together if the
inrush current was too high. This is why the
Appliance Module is limited to 500 Watts for
lamps. The Split Receptacle Module (SR227,
HAS-2040) is rated at 15 Amps unconditional
i.e. it will control 15 Amps of ANY kind of
load.
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Mike L. Sounds correct. Cold Inrush on a
lamps filament can be large. Also the surge
of a lamp blowing out at power up can be
damaging. I have blown a few Socket Rockets
with a 40 watt bulb blowing oit. They are
rated at 150 watts.