Building Two-Element 120V System

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butterblum

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I am working on a wiring schematic for a two-element system that utilizes two separate 120V power supplies. Each will come from a GFCI wall receptacle. The EZBoil I am using will control the second element with the built-in relay, per Auber's instructions.
One question I am running into is this: can I create one ground for the entire panel and join the ground from each supply to this central point?
If I wire an e-stop to send limited-current to this ground when tripped, will it trip both GFCI receptacles?
Any help or referrals are appreciated.
Thanks
 

Sparkncode

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GFCI's aren't intended for this use.
Better to use contactors to open both circuits in an e-stop situation

I would wire the contactors to require power to their coils to make them conduct (NO contactors) so that the e-STOP removed power from the coils causing both contactors to open.
A GFCI is a safety device and not a remote controlled switch.
No gaurantee with two GFCIs that they both open etc.
 
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butterblum

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The resident electrical guy (don't remember his name, I'm sure there are multiple) on this site had drawn up multiple schematics where he used an e-stop to return voltage to ground with a fuse and current-limiting resistor to trip the GFCI receptacle/breaker.
I believe the purpose of this was to cut off power at the house's panel in case there was a spill over or something. That way there wasn't any power to the control panel at all. Using contactors, you still have voltage at your control panel.
 

doug293cz

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The resident electrical guy (don't remember his name, I'm sure there are multiple) on this site had drawn up multiple schematics where he used an e-stop to return voltage to ground with a fuse and current-limiting resistor to trip the GFCI receptacle/breaker.
I believe the purpose of this was to cut off power at the house's panel in case there was a spill over or something. That way there wasn't any power to the control panel at all. Using contactors, you still have voltage at your control panel.
With multiple feeds, you would have to use a double (or more, one pole for each supply circuit) pole E-stop switch to return some line current from each of the supply circuits to ground in order to trip all of the GFCI's. If you only wire one hot to the E-stop switch, then only the GFCI on the associated circuit will trip.

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Bobby_M

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I am working on a wiring schematic for a two-element system that utilizes two separate 120V power supplies. Each will come from a GFCI wall receptacle. The EZBoil I am using will control the second element with the built-in relay, per Auber's instructions.
One question I am running into is this: can I create one ground for the entire panel and join the ground from each supply to this central point?
If I wire an e-stop to send limited-current to this ground when tripped, will it trip both GFCI receptacles?
Any help or referrals are appreciated.
Thanks
Talk more about this "built in relay". Do you mean the one inside the ezboil? You can just use two SSRs driven off the same ezboil and that keeps the two circuits segregated. Rather than an e-stop, just use a 2 pole switch to cut the hots on both circuits in one operation.
 
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butterblum

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Talk more about this "built in relay". Do you mean the one inside the ezboil? You can just use two SSRs driven off the same ezboil and that keeps the two circuits segregated. Rather than an e-stop, just use a 2 pole switch to cut the hots on both circuits in one operation.
I decided to use a 2-pole contactor - the hot lines from each supply will go to the contactor, and I will power the coil with the hot of the first supply, which will run through an NC E-stop. If I got the E-stop, the inputs of the contactor are the only points that see voltage.
Bobby, the more expensive EZBoil utilizes two 'alarm relays'. The first can be configured to power a second element. It is actually pretty neat - you can configure to controller to automatically turn on/off the second element at specific temperatures to prevent overshoot. I thought this was a better idea instead of manually turning the second element on and off, and you don't need a second SSR.
 

ba-brewer

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I decided to use a 2-pole contactor - the hot lines from each supply will go to the contactor, and I will power the coil with the hot of the first supply, which will run through an NC E-stop. If I got the E-stop, the inputs of the contactor are the only points that see voltage.
Bobby, the more expensive EZBoil utilizes two 'alarm relays'. The first can be configured to power a second element. It is actually pretty neat - you can configure to controller to automatically turn on/off the second element at specific temperatures to prevent overshoot. I thought this was a better idea instead of manually turning the second element on and off, and you don't need a second SSR.
Do you plan to use both elements during the boil?

If you use the relay to power a boost element you will not be able to regulate the power to that element using the power setting of the ezboil.

I bought the more expensive version for that feature but ended up just adding a second SSR and never using the feature. I have never had a issue with overshoot on my 2 120V controller just letting the ezboil control both elements. Using 2 SSR allows the ezboil to give a smoother reduction of power as well.
 
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butterblum

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Do you plan to use both elements during the boil?

If you use the relay to power a boost element you will not be able to regulate the power to that element using the power setting of the ezboil.

I bought the more expensive version for that feature but ended up just adding a second SSR and never using the feature. I have never had a issue with overshoot on my 2 120V controller just letting the ezboil control both elements. Using 2 SSR allows the ezboil to give a smoother reduction of power as well.
I have already committed to using the Auber enclosure with the heatsink that attaches at the top - I think there's only room for one SSR to mount to that heatsink.
I am going to switch back and forth between 3gal and 5gal batches - I have read that a 1500W element is more than powerful enough to maintain a boil of ~6gal in size. So the automatic on/off feature for the second element is worth more to me than linear control of the second element - I was going to just use it at max power and turn it on/off manually anyway.
 
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butterblum

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Definitely room for 2 SSRs - you just have to pay for the 60A heatsink.
I guess I will build it, experiment, and then go from there.
 
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butterblum

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I just realized that the built in relay can only handle 3A of current.....woops.
I guess I'm going to order another 25A SSR from Amazon (there is actually an Inkbird model available) and wire it like you suggested. I will drill and tap the necessary holes for both on the 40A heatsink.
The EZBoil has a separate setting that allows you to change the maximum power output as you near a temperature (mOut?). If I set this to 50%, I am effectively switching the second element off.
 

ba-brewer

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You will be glad later you added you second SSR upfront.

One persons boil is another persons simmer. My definition of boil has been lowered since going electric but I still like to see good movement.

If you have not got your kettle yet look for a narrow one vs wide. The 1.2 ratio kettle ratio that is suppose to be good for a proper boil may work for propane but not so well for electric. Tall and skinny is better electric.
 
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