Two branch - each 220v 30A feeds

[stopher]

a few strategic questions.

QUESTION1: i have a 100A subpanel with 2ct separate branches 30A-220V-GFCI breakers feeding 2 different 220v outlets.

i am considering operating TWO concurrent 5500W 220v electric coils...one on each of my keggles (HLT, BREWPOT), but I havn't seen others with designs doing this. Why not ?


QUESTION 2:
Some designs use PID and contactors, other have PID/SSR/CONTACTORS, but others seem to just use PID and SSR.

The draw on those coils is <25A, so i am thinking the SSR should handle it fine. I am thinking PID/SSR.

QUESTION 3:
If i pull 110 from 220V 3-wire, will the implementation trip my panel breaker GFCIs. I havn't ever split a 3 wire that uses GFCI and am thinking it will 'shorten' common-ground.

 

[BrunDog]

1. Because people don't generally have 2x 30A circuits available. If they want to use larger, they run 50A or 60A circuit. Also because you don't need to run HLT and BK concurrently, unless you are mashing and boiling at the same time to do back to back batches.

2. An SSR is always required with a PID. Mechanical contacts (relays) wear out prematurely with frequent high current switching. I don't think you will see any legit PID designs here without SSR.

3. You can't "pull" 120V from 240V 3 wire. Without a neutral, there is no return path. You can't return via the ground. The only way to make 120V is a center tap transformer. This is inefficient and should not be done practically. Use 240VAC components or run a neutral.

 

[jeffmeh]

And to add to 2), best practice with a PID/SSR is to add a mechanical contactor and switch so that you can cut both hot lines to the element, and know that it is off. SSR's leak current and can fail on.

 

[kal]

+1 to all of the above.

I get asked all the time why my design uses both SSRs and contactors as technically only SSRs could work, but I don't feel it's as safe. I ended up writing a few paragraphs about it in the "how it works" section of my heating elements wiring step.

Kal

 

[BrunDog]

I will admit, when I first looked at Kal's site, I scratched my head wondering why the contactors were there. But shortly after I realized this was a smart call. I wonder how many people went without only to learn the hard way that their element was on fire.

 

[jeffmeh]

And if I had a nickel for every time I posted some version of that.... lol

 

[stopher]

1. Because people don't generally have 2x 30A circuits available. If they want to use larger, they run 50A or 60A circuit. Also because you don't need to run HLT and BK concurrently, unless you are mashing and boiling at the same time to do back to back batches.

Ack. Process simply truly overrides theory. Thx

2. An SSR is always required with a PID. Mechanical contacts (relays) wear out prematurely with frequent high current switching. I don't think you will see any legit PID designs here without SSR.

Ack. Likewise I understand ssr good for modulation purpose and contact good for safety

3. You can't "pull" 120V from 240V 3 wire. Without a neutral, there is no return path. You can't return via the ground. The only way to make 120V is a center tap transformer. This is inefficient and should not be done practically. Use 240VAC components or run a neutral.

Ack. "3 wire" nomenclature is colloquial. Infers black,red,white,green.-always hated confusing issue that you successfully suggested. But could still pull a 120v phase from it safely to gain 120v for my pumps


cERTAINLY. Going with PID/SSR/Contactor. Safety insurance is cheap and easy to accept this design . Thx

Still thoughtful on 2x 30a 220v parallel branches. Actually seems safer and more scalable.

 

[BrunDog]

Gotcha. Yes, 12-2 means two plus the ground. I took your question literally. Well, since GFI compares the hot current to the neutral current, I would assume you can't use split breakers. I would just use 240VAC accessories (pumps etc ) and don't sweat it.

 

[ajdelange]

The GFI sums the currents in the two hots and the neutral. If the sum isn't 0 (or in reality very close to 0) it trips so yes, you can use split breakers as long as you use split loads. What you cannot do is connect, for example, a single 50A heater to two 30A breakers and assume the return currents will divide themselves up so that the return current on each breaker is equal to the current sourced by that breaker.