Hi
Just setting up my new 16 station gen 2.
I have two irrigation lines each with there own master valve.
They are a Front zone and a rear zone .these zones also contain zones 
Only one zone is on at any one time.
My question is
How do i wire up 2 master valves that operate independently of each other?
I gather putting both wires into the M slot will overload (3 valves on)
and is not an ideal way with both masters on
Thanks
Karl
Hey @Selfcontrol!
So the best solution for your set up is to wire both of your master valves in the master valve slot. Your controller can power three valves at once (that’s it’s max.) So both master valves will open, but since you don’t have any solenoids open on that system you shouldn’t see any effect on pressure or anything. Let me know if I can help with anything else!
McKynzee 
Hi there
I have a similar question to the OP. I have one irrigation area in the backyard and one in the front - water being fed from an independent tap in each location.
I have a master valve in the back and want to put one in the front yard.
Would it be ok to wire the master valve wire from the front master solenoid to the master valve wire directly on the back master solenoid OR would it be better to wire the front master solenoid directly back to the rachio module and twist the two pair of master wires together over there.
I’m assuming that’s the same deal with the common… Could I join them at the two solenoids or do I need to twist the two wires again at the rachio
@Dukebox, I’m sure a sprinkler professional may chime in here shortly. It will depend on the existing wire size and distance from the Rachio and the distance to the second valve. If the original installed use normal sized underground sprinkler field wire and the same gauge wire is used to run from the back yard master valve to the front yard master valve it should be fine. If it is easier or cleaner or shorter to run a new direct wire from the Rachio to the front yard master valve, then I’d do that.
Hi there
It’s about 5m from the Rachio to the backyard master valve… And then about 15m from that backyard master valve to the front master valve I want to install ( so about 20m from the front master valve to the rachio).
Using 0.5mm core wire.
Preference is to go to the backyard master valve as the extra 5 m into the shed has a full conduit and I doubt I’d be able to wedge another cable through.
Stupid me only ran a three core the 15m run to the front yard and I have two zones out there. It only dawned on me yesterday when I had a leaking solenoid that i should’ve put a master valve out there. Will have to run another single core from backyard to front but it’ll be a good risk mitigation strategy! Now to see if I can feed through a single core into the existing 20mm conduit which has a three core already in it…
@Dukebox - 20 m for 24 gauge wire shouldn’t be a problem. Just make sure you use water tight wire nuts or similar for field connections. I think you can take the master valve wire from the backyard and connect it to the front yard. As far as the common goes, common is common - you can connect to it anywhere, you don’t necessarily need to run a wire all the way back to the Rachio. If the front yard wires are running right by the pipe where you’ll put in the master valve, just connect to the common there. Again, use water tight wire nuts for the connection.
Cheers DLane
Makes sense - however I will need to run one more wire to do it I think as I have two zones in the front yard only a there core wire (one for each zone and one for the common… ) so I’ll need on more wore for the introduced master valve.