konstan@elmer-fudd.berkeley.edu (Joe Konstan) (11/22/90)
With all of the regular information about home key systems and mini PBX's a topic came up in a discussion with someone remodeling his home about similar equipment for electrical facilities. Since the technology is quite similar, and home wiring has been a topic here in the past, I thought this might be a good place to query: Idea: 1. This would be a system to allow dynamic (probably computer controlled, though hard jumpers would be an alternative) changes to a house wiring to alterwhich lights and outlets are controlled by which switches. It should support two-way, three-way, etc connections of switches and should probably handle at least 32 or 64 each of switches and lights/outlets. 2. This is not intended to be a remote-control facility (though I'd be interested if that were provided) so probably the best thing is software-controlled physical connections (hence the analogy with an old telephone switch). 3. The person who would program the connections is quite technically able. The other people in the house should just be using lightswitches as before. 4. No need to control everything in the house (i.e., anything unswitched (or obvious like the garbage disposal) can either bypass this or be configured once and left. 5. The home is being rewired anyway (next month or two) so that is not an obstacle. Neither is price. So, TELECOM-readers, any ideas? Joe Konstan konstan@postgres.berkeley.edu
dgc@math.ucla.edu (David G. Cantor) (11/23/90)
In TELECOM Digest, Volume 10, Issue 841 Joe Konstan asks for: > An electrical control system for a home to allow [inter alia] > in a home being rewired ... dynamic (probably computer > controlled, though hard jumpers would be an alternative) > changes to a house wiring to alter which lights and outlets > are controlled by which switches. Such a system, which also has remote control capabilities, already exists. It is called X10 and is available at places like Radio Shack, various Building supply centers, etc. A commercial, but completely compatible version, with many more and higher quality devices is sold by PCC (Powerline Control Components) of Advanced Control Technologies, Inc.800-229-7878, in Indianapolis, Indiana. PCC used to be a subsidiary of Leviton, Inc. Signalling is done over the power lines, using 121 kHz signals super- imposed at the zero-crossing of the 60 Hz power. It provides for up to 256 "devices". An rs232 connection is available, and a computer, so connected, can do a variety of things, including all of the obvious controlling and also signal translating (this can be used to efffectively change the device a switch controls). X10 supports dimming, relays, individual circuits and switches for one, two, or four devices as well as controller boxes with support for four, eight, sixteen, and 256 devices, etc. Remote controllers (both infrared and radio) are available. Both hard-wired and plug-in devices are available. Devices are available for 120 volts, 208 volts and 240 volts. For the most part prices are quite (in my opinion) reasonable. It's primary weakness is security. As it comes, any controller on the same power secondary (e.g., one operated by the neighbors' children) can talk to a device. When rewiring, as in this situation, the solution is simple: Insert a 1-1 isolation transformer between the electrical panel feeding the circuits to be controlled and the main power in. This completely isolates the X10 devices. Note that it isn't necessary to put the really heavy loads on this transformer. Heating, drying, electric stoves and ovens, etc. can be fed from another panel, not so isolated, and be controlled, if necessary, by relays powered from the isolated panel. In any case, such isolation for sensitive circuits is not a bad idea in any home! For many years, I have used such a system, in a small way, to control all of my computer components (i. e., my laser printer, my various external disk drives, etc.) and it has worked well. I don't have the usual mess of power cords going to a central switching point. Each is plugged into a plug-in control-relay plugged into an outlet near the device. In this case isolation is provided by power-line lowpass filters (also sold by PCC). I connect two isolated lines (on different circuit breakers) using a 1 microfarad, 600 volt capacitor. David G. Cantor Department of Mathematics University of California Los Angeles, CA 90024-1555 Internet: dgc@math.ucla.edu