Power Supply Cord Too Short

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?

To run that type of distance, why not just run a 110 closer to the Rachio location? Or, why not move the valve wiring closer to the outlet?

Stringing mains power overhead to the Rachio location would be obtrusive. Running mains power, underground, in a 2-foot trench (required by the regulations here), means lifting up newly paved landscaping and severing thick tree roots (a row of about 30 tall pencil pines). Access is limited, and so, trenching must be done by hand, destroying the established garden. The connection for mains power must be carried out by a certified electrician (again, local regulations), which adds to the cost. A 100-foot run of multiple core cable and shielded cable, further adds to the expense (more copper and greater potential for electrical interference). The Wi-Fi nearer to mains power, is poor, and so I would have to install additional hardware to extend the signal…

I could go on, but, why?

A length of heavy duty 2-core low voltage wire, costs peanuts to fit. Even a dedicated stabilized power supply would cost less to install (and be superior to the unregulated power adapter that comes stock with Rachio 3).

I could also opt for a beefier power adapter, but it troubles me that I read here in various posts, conflicting suggestions that the Rachio controller, might, or might not like, any more than 1000mA. I seek certainty, not maybe’s.

As I said earlier, I am questioning the suitability of Rachio for my purpose. I was kind of hoping that someone might chime in to persuade me that Rachio is a robust system. Rachio have not been able to confirm this to date, whereas, the big boys, like Rain Bird and Hunter (or even Opensprinkler at the other end of the scale), are much more transparent, with well-documented manuals that, for the most part, does away for the need of community support to begin with.