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Old 12-31-2012, 05:24 PM   #11
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Originally Posted by christpuncher123 View Post
Why have a switch for the heat, should the temperature controller not do that? Turn the PID on you have heat, turn it off you don't!
No one has addressed this so I will - the PID controls the SSR, and tells it when to turn on and off. The SSR controls ONE leg of the 240v (Assuming your heating element is 240v).

The second leg is always hot. Further, SSRs have been known to leak some amount of current, and that amount can be more than you'd expect. Additionally, they have been known to fail in the closed (IE on) position. All of these scenarios are bad.

So people put in a switch to manually cut power between the SSR and the element. Whether it's a heavy duty 30a rated switch that your lines run through, or a smaller switch that goes to a 30a rated relay, that's up to you. But again, it's safer than unplugging the element every time.

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now some of the more recent builds have been putting in breakers for each line, not necessary, but they are there for added protection, and so they don't trip their big breaker which could be in the basement - far away from the garage.
I'm going to disagree with you there Matt. Think of it this way - you have one main breaker to your house, probably 100 or 200A - why have a bunch of 15 and 20A breakers? The answer is not for convenience. I'm running 6ga wire off a 50A breaker to my panel, which are paired for each other. The 6ga wire cannot handle more than 50A which is why I have it paired to an appropriately sized breaker so the breaker will trip first.

Inside the panel, I have 10 and 14ga wires. If you were right, those wires would be allowed to try and carry 45A without the breaker ever tripping, but if you try and pump 45A through a 14ga wire... well, you'll let out the black smoke for sure and possibly cause further damage.

You want a breaker sized to protect the wiring that is down-stream of that wire. Whether you use a fuse or a breaker, it should be protected from overloading the current carrying capacity of the wire.


As for the other flashy lights and gizmos - they're just fun. I have seen a few builds on here that were VERY simple - single PID in a small box, no lights, nothing flashy. You could easily do something like that.

-Kevin
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Old 12-31-2012, 07:12 PM   #12
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Originally Posted by BadNewsBrewery View Post
No one has addressed this so I will - the PID controls the SSR, and tells it when to turn on and off. The SSR controls ONE leg of the 240v (Assuming your heating element is 240v).

The second leg is always hot. Further, SSRs have been known to leak some amount of current, and that amount can be more than you'd expect. Additionally, they have been known to fail in the closed (IE on) position. All of these scenarios are bad.

So people put in a switch to manually cut power between the SSR and the element. Whether it's a heavy duty 30a rated switch that your lines run through, or a smaller switch that goes to a 30a rated relay, that's up to you. But again, it's safer than unplugging the element every time.



I'm going to disagree with you there Matt. Think of it this way - you have one main breaker to your house, probably 100 or 200A - why have a bunch of 15 and 20A breakers? The answer is not for convenience. I'm running 6ga wire off a 50A breaker to my panel, which are paired for each other. The 6ga wire cannot handle more than 50A which is why I have it paired to an appropriately sized breaker so the breaker will trip first.

Inside the panel, I have 10 and 14ga wires. If you were right, those wires would be allowed to try and carry 45A without the breaker ever tripping, but if you try and pump 45A through a 14ga wire... well, you'll let out the black smoke for sure and possibly cause further damage.

You want a breaker sized to protect the wiring that is down-stream of that wire. Whether you use a fuse or a breaker, it should be protected from overloading the current carrying capacity of the wire.


As for the other flashy lights and gizmos - they're just fun. I have seen a few builds on here that were VERY simple - single PID in a small box, no lights, nothing flashy. You could easily do something like that.

-Kevin
Good points about the breakers in line.
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Old 01-01-2013, 03:08 PM   #13
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Quote:
Originally Posted by BadNewsBrewery View Post
No one has addressed this so I will - the PID controls the SSR, and tells it when to turn on and off. The SSR controls ONE leg of the 240v (Assuming your heating element is 240v).

The second leg is always hot. Further, SSRs have been known to leak some amount of current, and that amount can be more than you'd expect. Additionally, they have been known to fail in the closed (IE on) position. All of these scenarios are bad.

So people put in a switch to manually cut power between the SSR and the element. Whether it's a heavy duty 30a rated switch that your lines run through, or a smaller switch that goes to a 30a rated relay, that's up to you. But again, it's safer than unplugging the element every time.
Which is exactly why Kal's design uses a mechanical relay between the PIDs & the SSRs which I appriciate. I have first hand experience with an SSR that failed closed!

This is not a luxury it's a nessessity!
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Old 01-01-2013, 04:07 PM   #14
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I'm not familiar with Kal's schematic, but to clarify, I'm sure the mechanical relay is between the power and the SSR, not the PID and the SSR. Simply cutting off the signal voltage to the SSR would not stop current leakage or a failed SSR stuck in the on position. I'm pretty sure this is what you meant.

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Old 01-01-2013, 04:16 PM   #15
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Agreed. The mechanical disconnect, whether a 30A switch or a contactor, is between the SSR and the outlet for the element.

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Old 01-01-2013, 04:19 PM   #16
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Quote:
Originally Posted by gunmetal
I'm not familiar with Kal's schematic, but to clarify, I'm sure the mechanical relay is between the power and the SSR, not the PID and the SSR. Simply cutting off the signal voltage to the SSR would not stop current leakage or a failed SSR stuck in the on position. I'm pretty sure this is what you meant.
Yes , tied to the Element select switch so you're not just relying on the pid to fire the Element.
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Old 01-01-2013, 04:29 PM   #17
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Originally Posted by BadNewsBrewery View Post

I'm going to disagree with you there Matt. Think of it this way - you have one main breaker to your house, probably 100 or 200A - why have a bunch of 15 and 20A breakers? The answer is not for convenience. I'm running 6ga wire off a 50A breaker to my panel, which are paired for each other. The 6ga wire cannot handle more than 50A which is why I have it paired to an appropriately sized breaker so the breaker will trip first.

Inside the panel, I have 10 and 14ga wires. If you were right, those wires would be allowed to try and carry 45A without the breaker ever tripping, but if you try and pump 45A through a 14ga wire... well, you'll let out the black smoke for sure and possibly cause further damage.

You want a breaker sized to protect the wiring that is down-stream of that wire. Whether you use a fuse or a breaker, it should be protected from overloading the current carrying capacity of the wire.

-Kevin
I don't disagree with your explanation of what branch breakers are meant to do. However, I consider a brewing control panel and its associated heating elements to be acting as a single appliance. The resistive loads you design into this system are going to be very predictable. You used an example of a 14g wire trying to carry 45 amps, but you didn't explain a scenario where that would happen.

Let's say you have a 50amp breaker supplying the panel and the load break down is going to be two 5500w elements (sometimes run simultaneously), two pumps, and a couple PIDs. If the two element legs are just run off of distribution blocks and safety switched via contactors, what is the worst case scenario? That's a big 6/4 SJ cord going into the panel and splitting off to two sets of 10/3 SJ coming out. Let's assume everything downstream of the main distro block is 10g. Each element is going to pull 23 amps. I'm trying to figure out a situation where one element would pull something like 40a. Perhaps a really bad connection at the element?

I generally feel that you'd want to protect your PIDs from overcurrent with cheap, replaceable inline fuses, but I don't agree that branch breakers dedicated to each element is less than overkill on the safety side. Sure, safety is the one place where overkill is acceptable but I wouldn't say excluding them is particularly dangerous unless you're automating to the point where the whole batch will brew itself while you're not home.

Does anyone know if modern electric stoves have separate breakers for all 6 elements?

It's important to note that this is not advice. If you don't know what I'm saying, you should er on the side of safety and consult an electrician.
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Old 01-01-2013, 06:09 PM   #18
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Valid points, Bobby. I can't honestly say if the electric stoves have breakers, fuses, or nothing. I can't really think of a scenario off hand where my wiring will see unexpected loads, but I'm also not sure what routine scenarios would exist to cause the GFCI to trip but I've got one of them, too.

I guess for me it's the fact that these panels are wired up by amateurs using a mix of parts that surely haven't been tested / listed together as a system, and may not be listed at all... so there's no guarantee that everything will function properly so why not buy yourself a little extra security.

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5gal Saison
15gal American Pale Ale
20gal Belgian Wit (10 dumped)


Keg 1: Apfelwein
Keg 2: Belgian Wit (Failure)
Keg 3: American Pale Ale
Fermenting: Belgian Wit (Take 2)
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Old 01-01-2013, 06:45 PM   #19
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My understanding is that best practice is to protect the wiring with breakers or fuses, because in a worst case scenario the device drawing power could fail catastrophically and exceed its normal maximum amperage draw. Seems pretty easy to do in these applications, so I cannot see why one would skip it.

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Old 01-01-2013, 08:32 PM   #20
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On a safety stand point. How many people do brews on their stove? Is there Gfci Protection on your stove?

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