Multiplex wiring

I am not a fan of multiplex wiring. It just means that if there is a fault, you lose your lights, A/C, generator, maybe even slide-outs. It is just like those older Christmas lights where if one bulb blows, the entire string is useless.

What makes it even worse is that it becomes impossible to upgrade. Say your A/C has a compressor failure, and you can't find that exact model. With normal wiring, it isn't that big a deal. With multiplexed wiring, you have just lost all A/C functionality and either have to add in a separate thermostat, or use a non-ducted A/C with the controls on the lower unit itself. Same if you decide to replace your furnace, water heater, or other appliances. This is important, since with Truma making combination water heater and furnace units, you may not be able to find a separate furnace for sale in 5+ years.

Multiplex is great...as long as everything is working....when some particular function goes bad,you may even find the repair very simple - just replace the affected unit or controller. The bad part is the price of that part.

I have seen things like a ground short causing the controller to go bad. When there is a fault, the controller cuts off that item for a time, then back on -- it see's it's still shorted and cuts it out again -- sort of like a computerized automatic resetting circuit breaker. This is supposed to protect the system, but I have seen it fry the controller when left un-corrected for too long. The controller is very expensive.

Thanks for all the info!!!!! IT did help!!

KC

At 10:48 into this video; he says multiplex reduces the coach wiring by 40%:

https://www.youtube.com/watch?v=W4ZVyRfGrWQ

KC....I think you got some technical definitions, but maybe not what you asked. Multiplex systems let you turn things on and off fromm other rooms. From my bedroom control panel I can turn on my bedroom lights, main cabin lights, bathroom lights and night lights. The system usually gives you the ability to switch on many lights from one position without having to install many switches and a lot of wiring.

Basically every time you flip a switch it doesn't go directly the the item your turning on or off like it used to. Instead it goes to a computer which in turn, turns the device on or off.
The advantage (if it is one) is that they can use very tiny wiring for all the controls. In autos it means less weight.

Not sure if you are asking about Multiplex switching or pre wired Cat 5 or HDMI wires? It would be nice if there was HDMI cables run to the basement and to the bedroom.
Multiplex switching is great when it works, hard to trouble shoot when it does not, and expensive when you have to replace the Multiplex/computer boards. Often times it's just a bad ground, but finding it can take hours by someone who knows what's he/she is doing.
Using LED lights with smaller wires and conventional switches would be the best IMHO.

Not sales hype at all- it cuts down immensely on the amount of wiring needed. You have 5 light in the back, five switches up front *and* in the back. Wires needed between front and back for traditional wiring- ten (two per circuit for three way switch operation). Wires needed for multiplex- two. Want to add switched somewhere else? Multiplex, run two wires to them, paralleled with other switches. Want to add a third with conventional- good luck!
In addition- the control wiring need not carry any significant current.

Big words for Sales hype. A HDMI cable such as that used on your TV set is a Multiplex cable. It will support HD tv, full stero sound, and internet all in the same cable. CAT5 Ethernet cable was/is still multiples also.

Multiple signals are bused on one set of wires. Usually two twisted pairs. Sorta like your car's computer connections. Less wires, less connections, more microprocessors, more diagnostics. It's all great but not anywhere as easy to fix when it breaks...