Poor color coding flying leads Marmitek AWM2

Post by **MindBender** » Sun Apr 30, 2006 6:59 pm

The flying leads on the Marmitek AWM2 micro module are color coded in blue, brown and red. When installed properly, the external switch wil short the blue and the brown wire, which is highly unusual. Usually the lights go out when you short a blue wire with a brown wire

Now, the color coding of the blue wire is correct; It does carry the 0 volt level. But the brown wire does not carry the live level, nor should it be connect to the live voltage, in contrary to what one might expect. The brown wire carries a 5 volt DC detection signal that can be shortened to the 0 volt level by an external switch. This means you cannot connect the output of existing switche(s) to it because those will feed it with live voltage.

If you're using just one switch, hook it up as a potential free switch as directed in the manual. If you're using multiple cascaded switches (hotel circuitery), you may consider connecting the input of the cascade to the 0 volt wire, instead of the usual live voltage wire. This way, you can connect the output of the cascade to the brown wire of the module and all your switches will be able to operate the modele. Though it's still a strange idea: Connecting the 0 voltage wire to a brown wire to make the lights switch on...

Warning: Do you use the trick above on heavily loaded cirquits! A heavy load draws much current through the 0 wire, making it carry a voltage by itsself and thereby lifting the 0 volt level. I'm pretty sure the module cannot handle that. I'm very sure the module cannot handle live voltage on it's input wire (don't ask)

Post by **Consultant** » Sun May 07, 2006 5:13 pm

Because there exist a wide range of modules, first check the installer manual of the module. The wire dimension tells you that it can only withstand low current connections. So look the manual!
Second the blue wire tells you (indeed) it is connected to the neutral of the mains (not isolated from the mains voltage).
I see you asking: and brown is not connected to the phase? Indeed!
The following colors means: brown input 1, red input 2, orange input 3, yellow input 4 (do you know the color coding table of resistors?). In some cases a input can also be a output.
If a unit contains a black wire it means: common connection and isolated from the mains voltage (galvanical isolated).
And if you see a green wire , it means: a secondary power supply is needed for the inputs/outputs.

Post by **MindBender** » Mon May 08, 2006 1:06 pm

Thanks for clearing that up, Consultant! Yes, I'm fully aware of resistor and wire color coding (bachelor degree in electronics and computer sciences), but I still stand with my earlier statement that brown is a poor choice for a signal that must but connected to 0 volt and isn't live voltage tolerant.

How tolerant are these modules for the trick I mentioned above? It offers 0 volts on the input of the module, but from a switch elsewhere in the house, not from the blue wire the module offers.
Yes, I'm being careful to use the 0 volt from the same group as the unit is on; I'm very careful about that, so that's not a problem.
But if a group is heavilly loaded, the 0 volt level may be lifted a bit due to the resistance of the wiring and current flowing through it. Can the unit handle this low level of AC on its input?

Post by **Consultant** » Tue May 09, 2006 12:40 am

Yes, this low level is no problem for the input, if the amplitude is 3V or less.
Explanation: if you connect it in cascade then you add some differential voltage in series with the (5V) input level.
The input changes state if the voltage increased from 0V to more then +3V level or from +5V down to +2V level.
The inputs can handle external voltages of up to 10V without damage.
But this cascade connection is not usual and not recommended because if the external neutral connection is broken the 230V input voltage will distroy the module.

I hope this helps.