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Hot Common

ARGOS

LawnSite Silver Member
During our many engaging conversations in Colorado we talked about a "hot common" or "open common". I was talking to Fimco about a zone that was stuck on due to it having the common hot, I thought I miss wired a pigtail. He talked about an irritrol (I think?) controller that had a hot common. Fimco explained to me how it worked and also how the RM can create a hot common. Still cloudy. Any one up for rehashing this?
 

DanaMac

LawnSite Fanatic
I understand it a little, but not much. I'd like to hear some more from the likes of Pete and Mike about it. I have seen it on an older Irritrol, and maybe a Superior or something similar. Only seen it (felt it :)) a couple times.
 

1idejim

LawnSite Fanatic
During our many engaging conversations in Colorado we talked about a "hot common" or "open common". I was talking to Fimco about a zone that was stuck on due to it having the common hot, I thought I miss wired a pigtail. He talked about an irritrol (I think?) controller that had a hot common. Fimco explained to me how it worked and also how the RM can create a hot common. Still cloudy. Any one up for rehashing this?
I understand it a little, but not much. I'd like to hear some more from the likes of Pete and Mike about it. I have seen it on an older Irritrol, and maybe a Superior or something similar. Only seen it (felt it :)) a couple times.
i know the difference between hot and open......someone proceed, i'm all eye and ears.....
 

mitchgo

LawnSite Gold Member
Location
Redmond, WA
Is it hot enough to active a solenoid?

I've seen plenty of times the common reading 22V (In the field) with no zones on.

I'm curious what you guys are talking about
 
CALLING DAN HANSON >>>>CALLING DAN HANSON

I will venture where fools tread but The controller rather than activating a zone by making a circuit with the common and zone in question it always has power going to the common and just goes to the zone to complete the circuit.

SO..If you plug in your rainmaster and a zone kicks on it in my mind is because the zone that kicked on was grounding into the soil somehow maybe through a bad splice. A controller with a hot common you could go out into the field with the controller off. Take a loose solenoid from the truck. Attach one end to the common and touch the other wire to wet grass and it may activate.
 

Mike Leary

LawnSite Fanatic
I'm not too sure what we're talking about; I do know that there is 22 volts in the field at all times when a remote pigtail has been installed or with the RM clock in the "remote activated" position. I've been bit many times, it's like a bee sting. :cry:
 
OP
ARGOS

ARGOS

LawnSite Silver Member
CALLING DAN HANSON >>>>CALLING DAN HANSON

I will venture where fools tread but The controller rather than activating a zone by making a circuit with the common and zone in question it always has power going to the common and just goes to the zone to complete the circuit.

SO..If you plug in your rainmaster and a zone kicks on it in my mind is because the zone that kicked on was grounding into the soil somehow maybe through a bad splice. A controller with a hot common you could go out into the field with the controller off. Take a loose solenoid from the truck. Attach one end to the common and touch the other wire to wet grass and it may activate.
Still cloudy. How does it complete the circuit with a hot common?

Which irritrol was it?
 
Still cloudy. How does it complete the circuit with a hot common?

Which irritrol was it?
Think of it like this. Take a 24 volt adapter that is wired to a controller. Take the common off the terminal and attach it to the 24 volt adapter wire that is going to the common side of the 24 volt terminal of the clock. You have made the common hot. In 99% of controllers there is no power going to either the common or the zone wires until the zone is activated. In the old Irritrol double dial I believe the common was hot all the time.

Once again I am hoping Dan weighs in and sorts this out with trained lingo and not self taught lingo as I am.

This is also why when installing a pigtail it is very important to get the red/white and blue/white wires on the 24 volt terminal properly. In a situation in which the common was not hot it would be irrelevant which wire goes where on the 24 volt power source. When you wire the red/white into the common side of the 24v adapter you give the RM a hot common. On a male pigtail after you wire it in press your hand against the pins and you will be shocked.
 
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