Replace Rainbird ESP-6 which has a transformer inside

Hi, I’m trying to replace my Rainbird ESP-6 sprinkler controller with Rachio 3. I noticed the Rainbird controller has a small transformer inside (120V to 24 Vac).

I’m not sure if the transformer is part of the Rainbird controller as I haven’t actually uninstall it. I just opened to controller panel to see the inside and noticed it.

Assuming the transformer is a separate thing (and just happen the Rainbird inside has enough room to for that transformer), Is it possible to reuse that transformer for my Rachio 3 ?

Here are the images of the Rainbird ESP-6


It looks like it is part of the Rainbird controller. How would you reuse the transformer when it inside the Rainbird box? It would be possible, but the Rachio uses a barrel connector instead of wire terminals for power input. It looks like the Rainbird box is inside (possibly garage) and with sheetrock walls. It is hard to tell, but kind of looks like a power cable attached to the bottom (it is an extension cord or something else?). If so, is that plugged in? If so, I would just plug in the Rachio. Otherwise, I would suggest you or an electrician replacing the cable with an outlet box, maybe even surface mount, for the Rachio to plug into. Other options probably exist.

I’m sure there would be some way to re-use it, but I wouldn’t advise it.

Get a Rachio outdoor enclosure. The same way that your Rainbird is hardwired (the tan wire nuts above the transformer), you can hardwire the Rachio enclosure, which gives you a build in plug for the power brick.

Thank you @Thomas_Lerman and @tmcgahey !

The Rainbird is installed inside the garage.

I’m not sure what is that angled pipe thing that is connected to the bottom

That pipe seems to be connected to the transformer unit which has the two power cables coming out of it and connected to the two 24 VAC.

IIUC, to replace with Rachio3, I still need a transformer - correct?

@tmcgahey, for the outdoor box that you recommended, does it contain a transformer? And also, I assume it can also be installed inside correct?


Forgot to include one more picture

It sounds like within the pipe with the elbow connected to the Rainbird is the input to the transformer at 120VAC. Then the transformer changes it to 24VAC which drives the Rainbird and valves. Does that sound correct to you?

The options seem to be (turn off the breaker that provides the Rainbird power first):
Remove the Rainbird without damaging or cutting the wires coming through the pipe, then either:

  1. Connect a box & outlet to the same connection the is currently on the Rainbird. Rachio would be nearby and plug the Rachio wall wart into that and then into the Rachio
  2. Install the outdoor enclosure that @tmcgahey referred to which should be fine indoors (could always leave the door open or maybe take it off). The enclosure has an outlet built into it and you could connect the pipe & wires into that very similar to the box & outlet I just mentioned.

Personally, I probably would do the first one as it would be less expensive and I could use the other 1/2 of the outlet for something else.

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Thanks @Thomas_Lerman.

That sounds right to me.

But I need two wires at 24Vac going into the two barrel connectors on rachio3 (screenshot below) . Are you saying I can reuse the existing transformer (which has the two wires coming out at 24 Vac)?

Maybe I mis-understood.

Are you saying I don’t need those two wires (at 120 Vac) coming out from that elbowed pipe?

Since rachio3 already comes with a power adapter so just plug that to the wall outlet and the other end (which is a male barrel connector) to plug into Rachio3 a female connector (circled in below picture).

So I don’t need to wire anything to that two 24 vac labels (cross them in below picture)

Is everything correct?

Yes make an outlet out of the 120 volts from that pipe, plug in the rachio wall work, and then plug the barrel connector into the rachio. Definitely do not try to put 24 volts onto those terminals


I already have a wall outlet nearby. So I mean I don’t need to use those two120 vac wires from the pipe - correct? Or perhaps those two wires are dedicated for the sprinkler controller so I should stick to them?

Oh, I see. I would likely use the already existing outlet. I do wonder if the wires connected through that pipe is going to the outlet. You might be able to check it out when you disconnect the Rainbird. I would just make sure you take care of those wires properly.

Thanks @Thomas_Lerman.

I recalled they were separated becoz I have a switch that can turn off the power of wall outlets in garage except power to the Rainbird.

So I may want to use those two red wires coming from the pipe. Probably buy the Rachio outdoor enclosure box since you guys mentioned there is a built-in outlet where I can hook up the wires from the pipe to the built in outlet.

So should I use both red wires from the pipe or just only 1 of them to hook up to the black wire of the built-in outlet of the enclosure box?

You definitely need a hot and neutral, if no ground is supplied that is probably okay. If both of the wires are red coming out of the pipe, I am not sure which is which. That would be wise not have power dependent on a switch hike that outlet is.

Thanks for the advice.

I think the green one is neutral. The dark bare wire (coming out from a hole above the transformer) may be a ground wire, but not sure.

The two red wires from the pipe (thru the transformer) are currently connected to the two 24 VAC terminals of the Rainbird. If they are both NOT controlled by any switch, can I just pick one of them? I would imagine they both supply 24 VAC, so they should not have any difference - is that correct? Or I’m missing something there?

@leilobound - the 120 VAC supply line is probably the lower set with a black, white and bare (copper) wire. Those are the wires that would be connected to the Rachio external enclosure. Everything else from the Rainbird should be abandoned.

On the right side the white Com and Station 1 - 5 or 6 wires will go to the Rachio C and 1 - 6 terminals.

Thanks @DLane!

It’s amazing you can tell by just looking at the picture. I have no idea. Just curious - what is the upper set for?

@leilobound - Educated guess/deduction/not my first rodeo:

  1. Non-metallic sheathed conduit (AKA Romex) normally comes with a black wire for hot, a white wire for neutral and a bare ground wire. That is why I’m assuming the bottom set of wires comes from the circuit breaker.

  2. The transformer will have the input wires on the opposite side of the output wires. As the wires exiting the top of the transformer go to the Rainbird 24 VAC terminals, the 120 VAC input wires will be on the bottom of the transformer. I’m guessing the upper pair of wires connect to the input side of the transformer.

Worst case I have the wire sets reversed. It will all be readily apparent when the Rainbird is uninstalled as the wires coming from the wall will be the input source to the outdoor enclosure/wall plug which ever you decide.

Enjoy and welcome to the community.

That is right about the Romex and it looks like it does have Romex when I zoom way in on my phone. If a very individual wires, ground is usually green. If you do it yourself, make sure you turn off the breaker and double check with a multimeter that the power is off. If you do not know that much about it, I probably would suggest getting somebody that does, just to be safe.