House renovation, how to a good electrical system oriented to MySensors?

[alowhum]

Thanks. But my apartment is only 10 from front to back. I thought that if I place the power source in the middle, then the maximum distance to an endpoint is about 5 meters. The same as the maximum length of USB extension cords.

Would you still recommend against it for those lengths?

[scalz]

@alowhum
it could work. voltage drop mostly depends on the load, wire size, voltage source and cable length. You could also use ethernet cable, it's quite cheap and shielded, and you could use pair of wires for power etc. This might reduce a lot the voltage drop if it's an issue.
you can find voltage drop calculator on google.
Be careful, some cheap arduino have cheap/fake 12v ldo, which can heat and die when running on 12v after a while

[alowhum]

Thanks! Ethernet cable is a great idea (since it's also used for power over ethernet it makes sense). Unfortunately I've already been donated some speaker wire. It's gauge is larger than ethernet, and it's made of copper, so I think it should be ok.

[skywatch]

@alowhum In that case I would suggest you try it with 'floating cables' and see how it goes.

It may be 5M direct, but by the time you have routed the cables it could be a lot more. Cable cross-sectional area will have an impact too. But as you add more nodes with sensors, diaplays etc then the issue will be more pronounced.

Be sure to check the max rated voltage and current of the cable you eventually use. Also check it is compliant with any building/electrical regulations as a fire caused by non-compliant installation will often result in insurance being denied.

If you can, run the cable as a loop as this will minimise voltage 'sag' at the end of a run.

[alowhum]

Thanks for the advice @skywatch! You're right about the distance increasing, for sure. Then again, if the voltage drops from 12v to, say, 10 volt, would that matter? The Arduino itself will still bring it down to 5, and it can handle anything between 6 and 12 as an input on the jack plug?

What do you mean with running it in a loop? Where could I learn more about that?

[Sasquatch]

@alowhum said in House renovation, how to a good electrical system oriented to MySensors?:

What do you mean with running it in a loop? Where could I learn more about that?

wires in the loop:
PSU-----GW----Node1----node2
|____________________________|

Use switching regulators to keep current down.

[skywatch]

@alowhum Voltage drop will be proportional to the current drawn by devices, so it may be acceptable at first but get worse as more items are added to the system.

As for the 'loop' look on google for 'ring main wiring'. Essentiall instead of a power line going from psu to a number of nodes in a single spur that ends with the last node, the connection for the last node goes back to the psu.

Bit like I said, just run some of the cable you want to use across the floor and try it out before installing it all.

@Sasquatch that is not the way a power ring main is wired, sorry if I was not clear on what I meant. Hopefully it will be clearer after seeing it on google/youtube. Also, for a mains powered system a linear regulator might be a better choice. Not as efficient I agree, but less noisy output and the power savings would not likley show on the electricity bill! ;)

[Boots33]

@alowhum There will be a wealth of information out there on the net and probably also at your local library. look for resources about remote cabin power systems and also even the larger 5th wheeler type caravan systems will be helpful reading. You will also need to check your local building codes to see if there are any rules to be adhered to.

When we built our house (about 15 years ago, long before i discovered MySensors :) we ran a low voltage backbone cable throughout the house. From this backbone we ran smaller cable drops to every room in the house. Many of these are still not in use but as others have said the cost of running wires is relatively cheap when you are building. Of course we still have mains power as well and use the low voltage system to compliment this.

In those initial years the 12v system was used primarily for lighting systems such as night lights etc. As time progressed we installed 12v outlets in the bedrooms and these now are used to power bed/reading lamps. The small 12v downlights have also proved to be very easy to convert over as well. These were initially halogen bulbs but now there is a good range 12v LED replacements for just about any type of socket. Once I discovered MySensors and home automation then the 12v system became even more useful now powering several nodes and even the gateway.

Right from the start we ran our system from a battery with solar charging and in 15 years it has never let us down. Voltage drop will always be a thing to watch, but with LED's low power draw and as you have surmised the ability of arduinos to run well below 12v it will usually be of little practical concern. Unless of course you are thinking of running more than lights and nodes.