Upgrading my 30 amp E-system...

[erikrocks]

to a system in which I will be able to fire both of my 5500 watt elements at once. My current system (thanks again, P-J) has been working perfectly for almost two years, but I'd like the ability to brew back to back batches where I can heat strike water for brew #2 while boiling brew #1.

So, instead of buying a new 50 amp breaker, ripping out my 10awg wire and buying 4awg, etc, I'm think I'd much rather buy a second 30 amp breaker for my panel, run 10awg to a second spa panel, and have each element + PID/SSR on a separate circuit, yes housed in a single control box.

My questions are: 1.) Has anyone done this? 2.) Can this be done by simply switching out the DPDT switch for 30 amp on/off switches, an extra e-stop, an extra PID/SSR, and extra fuses/resistor for the second circuit?

Here's my current P-J diagram:

No bells, whistles, lights, DIN rails, internal breakers, etc...and I'd like to keep it that way. Doable?

 

[dcbw]

I'm will eventually be doing the exact same thing since I built my panel simple to get started. I now have two 30A breakers, two runs of wire, and two 50A spa panels. Just waiting until I have time to update my control panel.

The big thing to remember is that the second 30A circuit must be fully isolated from the first. This means a DPDT E-Stop switch, a second PID, a second SSR, etc. This doesn't mean that the 120V parts of the panel must be separate at all, the 120V for the second PID can definitely be supplied by the existing 120V bus you currently have wired up. Just that the new 30A bits must be separate.

Here's a diagram that PJ drew for me a long time ago, that was going to be the final diagram for my full panel. It's a bit more complicated than yours, since I went with a key switch and contactors between the SSR and the elements. But it should give you an idea. Note how the second 30A source (the lower one on the left) is only ever connected to it's key-switch contactor, it's SSR, and its element. It has no 120V stuff at all. The E-Stop is now a DPDT to ensure that the two 30A circuits are never directly connected except when they are shorted to ground (triggering the GFCI spa panel).

 

[dcbw]

One last thing; note that the second 30A source's ground isn't hooked up. I believe that's just a simplification so that a second set of resistors and fuses is not required. But this is fine... When the E-Stop is tripped, that will trip the first 30A source's spa panel, which cuts power to the key switch and to the key switch contactors. Those in turn cut power to the entire panel, since the first 30A source controls the 120V bus that all the control logic is powered from. Because the key switch contactor coils are now de-energized, both 30A sources are now cut.

That said, I'm probably going to hook up the second 30A source's ground anyway, since I had to buy the fuses and resistors in multi-packs and I have enough space. But it will again be separate from the existing ground circuit to ensure that the second 30A source's spa panel trips at the right times.

 

[erikrocks]

Thanks for sharing. But is it necessary that my build include contacters and coils? Can't I do without them?

 

[dcbw]

Thanks for sharing. But is it necessary that my build include contacters and coils? Can't I do without them?

No, it's not necessary to have contactors. The first two on the left are to support the key switch which you don't have and thus you don't new them. The second two connected to the SSRs are there because it was easier to buy them instead of finding a 3 position element select switch that's 30A capable. Most aren't.

So in conclusion, you don't need any of the contactors. Here's what you would do:

1) add a second PID and SSR. Keep the PID on the original 120v supply. Hook the second PID control lines to the second SSR control

2) assuming your Estop switch has blocks on the bottom, get a second NO block and hook the second 30A supply to it like you have for the first. This maintains electrical isolation of the two 30A supplies.

3) hook the second 30a ground to the second element

4) get a second 30a capable double throw switch, the same as your first one, and hook two poles up to your second element

5) hook Hot A/Line 1 to one side of the new SSR output, and the other new SSR output to your new switch from (4)

6) hook Hot B/Line 2 to your new switch from (4)

And I think that's it. I could try to hack up pjs diagram if this isn't very clear.

 

[erikrocks]

...and 4 months later, I'm ready to start my upgrade. I think I've settled on this P-J diagram:

My questions:
1.) Should I insert a full system on/off button where dcbw has the "power key" in post #2 of this thread? I don't want/need a key...I wonder if I should have a way to turn off the entire system. If so, can I simply use one of these illuminated buttons that I'm using to turn on the elements, PIDs, and pumps?

2.) How much of this DIN rail will I need to mount one 15a and two 25a circuit breakers?

Thanks in advance, all. Electric brewing rocks.

 

[erikrocks]

Also...is there any reason to use any gauge wire thicker than 10# inside the box? It looks like, since I have 25a breakers inside the box, I don't need to go any thicker. True?