Not all installations allow a Rachio controller to be mounted in easy reach of 110VAC mains power. If the 24VAC power adapter cable is too short, adding an extension to this might be the only practicable option for some users.
I reached out to Rachio Support several days ago about my proposal to extend the low voltage power cable by 100 feet.
For those who are interested, here is a simple explanation of what happens when your power cord is very long.
Rachio controllers, like all electronic devices, are engineered to operate at a specific voltage (24VAC) with adequate current (1000mA or 1 Amp). If the power supply cord is too long, resistance inherent in copper wire, will result in a voltage drop that could make your Rachio, very unhappy, or not work at all. It can also stress-out your 24VAC power adapter, causing it to overheat and shut-down.
Think of voltage and current like water pressure and water flow passing through your irrigation line. The balance of pressure and flow must be just right to make that last sprinkler at the end, work optimally for that perfect spray pattern to happen. Too much pressure, and the head will pop off, while, too little flow, will reduce the sprinkler to a trickle. It’s a tweaking thing between pressure and flow.
A simple fix to encourage adequate water through the water line is to increase the diameter of the pipe to the end sprinkler. Similarly, a way to reduce the resistance of a long power cord, is to increase the diameter of the copper wire to the controller.
Replies to other posts suggest that a regular, off-the-shelf, 6 or 10 foot power extension cable from Amazon, will extend power to Rachio, without adverse affect. But what if you needed a longer extension cable? What if you live in a community that is is prone to electrical brown-outs?
Rachio controllers, like all well-designed electronic devices, are required to be engineered to accommodate fluctuations in voltage, plus an additional margin to accommodate the unregulated power adapter included with the kit. For my installation, I referred to one of the many online Voltage Drop Calculators to determine that a 100 foot extension cable made up of robust 16 AWG copper wire would reduce voltage drop to less than 1%. A cable to achieve this could be made up for dollars.
Rachio engineers know exactly how much voltage drop a Rachio 3 can cope with under full load, but sadly, perhaps to keep things simple, this particular specification is not readily available to us.
I reached out to Rachio Support to confirm the power requirements of Rachio 3 so that I could make an educated decision about whether to use a higher gauge copper extension cable, install a dedicated power stabilizer with more grunt, or use both if necessary. This is the best way to ensure that my Rachio controller would receive an adequate and constant supply of super-clean power.
In the unlikely scenario that Rachio 3 would be unhappy with a 1% voltage drop, I would want confirmation of this, just the same, as I would not feel comfortable with the product, and move on to something else.
Sadly, Rachio Support was of no assistance, referring me to the Community, instead. Suddenly, I am not so concerned about power requirements any more. With the investment in multiple controllers I will need to purchase, I am now looking at the bigger picture and wondering how helpful Rachio Support really is?