My 240v Panel Plan - Could you sanity check me?

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MackerelQ

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This is my plan for my new 240v brewery controller. Please forgive some of my lack of proper diagram convention- I'm using MS Paint 😆.

If anyone could be so kind as to sanity check my design, I would completely appreciate it. I think my biggest point of concern is proper use of fuses. I've even seen a few diagrams with a fuse going to the SSR, so if you could maybe make some suggestions on where they should be, proper amperage, and fast vs. slow blow that would be super helpful. If I can clarify anything about the design, please feel free to ask.

One additional question I have, if anyone has any input on this, is whether a plastic enclosure is advised/not advised and why. I don't have any DIN components, so don't really think this is a concern. Any concern about grounding with plastic?

PanelWiring2.png
 
I usually plastic enclosures. Cheaper, easier to drill.

Personally I always appreciates when there are MOV surge protection in a box.
 
You need a 240v indicator lamp across your heating element. I made the same mistake that you have sketched out here -- when the element is off, the heating element itself will still pass enough power through it to give you not quite 120v across your LED, but enough to make it still light up. After all, it is still a big resistor. So instead of having +120v through the SSR, you'll have like -80v or so through the always-on leg attached to the element, which again, will be enough to light your LED up. (Unless you switch both legs, you'll always have some power in there even when the SSR is off, and by hooking your LED to neutral, that means you'll always have a power differential versus the neutral; versus a 240v LED hooked across the element, which will show 0v and thus not light up when the SSR is off).

As for the rest of my design, I used a plastic enclosure with DIN rails attached inside of the enclosure. I also used DIN-mounted circuit breakers rather than fuses, but the effect is the same. My main caution is against the use of that 120v LED to indicate heater element power.
 
Your fusing strategy looks fine.

There are a number of problems with this design:
  • Neutrals do not need to be switched
  • Black hot phase and neutral should not connect to the float/no float switch selector switch
  • The element firing indicator lamp should connect to the red hot phase rather than neutral
  • You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)
Brew on :mug:
 
I usually plastic enclosures. Cheaper, easier to drill.

Personally I always appreciates when there are MOV surge protection in a box.
Thanks for the suggestion on the MOV; I hadn't heard of that before. Do you have a suggested placement for one (or more if required) and any advice on what type/rating/etc. for it/them? Any preferred place to get this?
 
You need a 240v indicator lamp across your heating element. I made the same mistake that you have sketched out here -- when the element is off, the heating element itself will still pass enough power through it to give you not quite 120v across your LED, but enough to make it still light up. After all, it is still a big resistor. So instead of having +120v through the SSR, you'll have like -80v or so through the always-on leg attached to the element, which again, will be enough to light your LED up. (Unless you switch both legs, you'll always have some power in there even when the SSR is off, and by hooking your LED to neutral, that means you'll always have a power differential versus the neutral; versus a 240v LED hooked across the element, which will show 0v and thus not light up when the SSR is off).

As for the rest of my design, I used a plastic enclosure with DIN rails attached inside of the enclosure. I also used DIN-mounted circuit breakers rather than fuses, but the effect is the same. My main caution is against the use of that 120v LED to indicate heater element power.
Thanks, @BAF, this is the real world experience/information that is truly invaluable.
 
Your fusing strategy looks fine.

There are a number of problems with this design:
  • Neutrals do not need to be switched
  • Black hot phase and neutral should not connect to the float/no float switch selector switch
  • The element firing indicator lamp should connect to the red hot phase rather than neutral
  • You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)
Brew on :mug:
@doug293cz , thank you so much for looking at my design. I have looked at some of your reference designs and took inspiration for mine. If you don't mind, would please indulge me some questions and responses to your advice?

1. Neutrals do not need to be switched
The switches I have are 250v 30A illuminated DPST which require the neutral or second hot leg to light the bulb. Based on this, am I wrong on what I have sketched?

2. Black hot phase and neutral should not connect to the float/no float switch selector switch
The selector switch is illuminated, so it needs the hot/neutral or hot1/hot2 connected to the lighting block to light the lamp.

3. The element firing indicator lamp should connect to the red hot phase rather than neutral
Is that due to what @BAF was saying about needing a 240v indicator lamp for the element?

4. You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)
My float/no float switch is also an element enable/disable switch by switching the positive DC control lead to the SSR. I know this does not address SSR malfunction/failure, but it seems to be a good initial control mechanism. The contactor I have in the system switches the hot out to the SSR and the always on leg to the element outlet utilizing a lighted switch. Is my presumption that this would do what you are prescribing inaccurate?

Thank you again, I really appreciate your advice and assistance.
 
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4. You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)
My float/no float switch is also an element enable/disable switch by switching the positive DC control lead to the SSR. I know this does not address SSR malfunction/failure, but it seems to be a good initial control mechanism. The contactor I have in the system switches the hot out to the SSR and the always on leg to the element outlet utilizing a lighted switch. Is my presumption that this would do what you are prescribing inaccurate?

Thank you again, I really appreciate your advice and assistance.

Just specifically about this design element, I take the approach that the main contactor that cuts both hots would be better placed as an element enable/disable. It's a matter of preference, but I would rather have the ability to access the pump on/off and mess around with the DSPR programming while I have the element output voltage completely disabled. To do this, I move the contactor to just before the L6-30R output. I do also have a single main panel on/off switch but it simply precedes all the low current devices.

I would simplify the float situation too. Without needing to switch, the way I would force a bypass of the float is to just make up a plug with the tip and sleeve shorted together and insert that if you have a float failure and need to finish the brew day.
 
@doug293cz , thank you so much for looking at my design. I have looked at some of your reference designs and took inspiration for mine. If you don't mind, would please indulge me some questions and responses to your advice?

1. Neutrals do not need to be switched
The switches I have are 250v 30A illuminated DPST which require the neutral or second hot leg to light the bulb. Based on this, am I wrong on what I have sketched?

You show the neutral passing thru the switch to the load, so the diagram is confusing.

2. Black hot phase and neutral should not connect to the float/no float switch selector switch

The selector switch is illuminated, so it needs the hot/neutral or hot1/hot2 connected to the lighting block to light the lamp.

To do what you are proposing the switch would need four NO contact blocks, plus the lamp block. You need separate contacts for the low voltage controls signals to the SSR, and the line voltage for the lamp. Also, how will the lamp logic work? On for only one of the On switch positions, or On for both On switch positions? If On for both, how do you know from the light which mode is enabled?

3. The element firing indicator lamp should connect to the red hot phase rather than neutral

Is that due to what @BAF was saying about needing a 240v indicator lamp for the element?

Yes

4. You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)

My float/no float switch is also an element enable/disable switch by switching the positive DC control lead to the SSR. I know this does not address SSR malfunction/failure, but it seems to be a good initial control mechanism. The contactor I have in the system switches the hot out to the SSR and the always on leg to the element outlet utilizing a lighted switch. Is my presumption that this would do what you are prescribing inaccurate?

No, as you have to shut off the entire system to isolate a failing (not responding to control signals) SSR. Switching control signals does nothing to shut down this failure mode. @Bobby_M gives some good advice about changing the contactor to only control the element power, rather than all power. It addresses the ability to shut off a failing SSR, while not shutting down the whole system. You don't really need to control power to the low power devices with a contactor, or even a switch if the panel can be unplugged from the power source (all your devices internal to the panel draw much less than 1A total.) It's useful to have the DSPR power come on before the element power is enabled, as the DSPR will try to turn on the SSR/element if it was not left in the correct state at the end of the previous run. I prefer designs with a main power contactor, and element enable contactors, as they allow the implementation of a "Safe Start" interlock. The interlock prevents main power from being turned on if any pump or element switches are on. Prevents unexpected behavior on power up.

Thank you again, I really appreciate your advice and assistance.

Answers in blue above.

Brew on :mug:
 
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Just specifically about this design element, I take the approach that the main contactor that cuts both hots would be better placed as an element enable/disable. It's a matter of preference, but I would rather have the ability to access the pump on/off and mess around with the DSPR programming while I have the element output voltage completely disabled. To do this, I move the contactor to just before the L6-30R output. I do also have a single main panel on/off switch but it simply precedes all the low current devices.

I would simplify the float situation too. Without needing to switch, the way I would force a bypass of the float is to just make up a plug with the tip and sleeve shorted together and insert that if you have a float failure and need to finish the brew day.
@Bobby_M, thanks for that insight on contactor placement; I really hadn't thought of needing to be able to use the rest of the panel with the power completely cut to the element. Really good advice.

With regard to the float switch situation, I have it set up to either use the float or not, possibly more times not. I added the float switch option as I'm going to make my own water distiller and will be installing the float switch there so I don't have to babysit it the whole time without burning out my element. I think having a 3 way selector switch is a convenient and not too complicated way of selecting whether I want to use the float switch or not.
 
1. Neutrals do not need to be switched
The switches I have are 250v 30A illuminated DPST which require the neutral or second hot leg to light the bulb. Based on this, am I wrong on what I have sketched?

You show the neutral passing thru the switch to the load, so the diagram is confusing.
@doug293cz, yes, in the diagram I have the neutrals, as well as one of the hots, switched on the main power switch as it is an illuminated DPST switch. Is this an issue switching the neutral along with the hot on a double pole switch? If I do not connect the neutral, it does not light up. I realize the neutral does not need to be switched, but is there a problem I am unaware of in doing so?

2. Black hot phase and neutral should not connect to the float/no float switch selector switch
The selector switch is illuminated, so it needs the hot/neutral or hot1/hot2 connected to the lighting block to light the lamp.

To do what you are proposing the switch would need four NO contact blocks, plus the lamp block. You need separate contacts for the low voltage controls signals to the SSR, and the line voltage for the lamp. Also, how will the lamp logic work? On for only one of the On switch positions, or On for both On switch positions? If On for both, how do you know from the light which mode is enabled?
The switch I plan to use is the SW19 switch from Auber, Link. According to the description, "The lower half of this switch can be divided into three blocks: one middle block for the LED light, and two switch blocks on the side. Each block is independent of each other." So, from what I can see in the product pictures and description I believe this should work as I am intending. Am I interpreting it wrong? As for the lamp logic, the lamp on the switch I believe would be always lit. I was not planning for the light to indicate which mode was enabled, only the switch positioning.

4. You should consider adding an element enable switch and contactor so that you can shut off the element in the event of SSR latching or total failure (should be a lighted switch)
My float/no float switch is also an element enable/disable switch by switching the positive DC control lead to the SSR. I know this does not address SSR malfunction/failure, but it seems to be a good initial control mechanism. The contactor I have in the system switches the hot out to the SSR and the always on leg to the element outlet utilizing a lighted switch. Is my presumption that this would do what you are prescribing inaccurate?

No, as you have to shut off the entire system to isolate a failing (not responding to control signals) SSR. Switching control signals does nothing to shut down this failure mode. @Bobby_M gives some good advice about changing the contactor to only control the element power, rather than all power. It addresses the ability to shut off a failing SSR, while not shutting down the whole system. You don't really need to control power to the low power devices with a contactor, or even a switch if the panel can be unplugged from the power source (all your devices internal to the panel draw much less than 1A total.) It's useful to have the DSPR power come on before the element power is enabled, as the DSPR will try to turn on the SSR/element if it was not left in the correct state at the end of the previous run. I prefer designs with a main power contactor, and element enable contactors, as they allow the implementation of a "Safe Start" interlock. The interlock prevents main power from being turned on if any pump or element switches are on. Prevents unexpected behavior on power up.
Thank you and @Bobby_M for this advice on contactor placement. While I will probably not install a second contactor, I will definitely consider moving it to enable/interrupt the element power.
 
Based on the advice given, this is what I feel fits the suggested modifications. Please feel free to let me know if anything looks weird.
PanelWiring3.png
 
I think it will function reasonably. I do see a little redundancy with the float switch and the element power switch. Spit-balling a few alternatives..

1. SW16 switch for the element enable switch, have it light when the contactor is closed. Select the 240v indicator voltage and you can feed the LED block from the load side of the contactor. This light means the element is "capable of firing". You'd have to move the SSR downstream for this otherwise the light would flash on only when the SSR closes.
From there, you can either dump the On/Off/Float selector in favor of a float bypass "plug" or make that switch just a "float bypass" where it shorts the float leads.

2. You could combine both the element enable contactor closing with the float enable/bypass function on the same switch. It's a little complex, but hear me out because it only require one extra switch block.
SW19 switch, that's 3 position. Center will be off, element can't fire.
In the left position, element enabled and ignores float. Wiring: a NO contact passes voltage to the contactor coil. A stacked NO contact shorts across the float.
In the right position, element is enabled but abides by float position. Wiring: A NO contact passes voltage to the contactor coil.
The LED block can be lit by contactor load side hots but it won't be visually obvious that the float is open or closed. The "element firing" light, or lack of of it lighting would be the indication that the float is not closed.

3. Depending on your level of comfort with the idea of running 120v through the float switch (most are rated for it), the element enable function can be run through the float before hitting the contactor coil. The advantage here is that the element enabled LED, if wired on the load side of the contactor, will alert you when the float is not closed. That is, with the element enable switch position closed, the lack of LED illumination would show the float is not satisfied.
 
I think it will function reasonably. I do see a little redundancy with the float switch and the element power switch. Spit-balling a few alternatives..

1. SW16 switch for the element enable switch, have it light when the contactor is closed. Select the 240v indicator voltage and you can feed the LED block from the load side of the contactor. This light means the element is "capable of firing". You'd have to move the SSR downstream for this otherwise the light would flash on only when the SSR closes.
From there, you can either dump the On/Off/Float selector in favor of a float bypass "plug" or make that switch just a "float bypass" where it shorts the float leads.

2. You could combine both the element enable contactor closing with the float enable/bypass function on the same switch. It's a little complex, but hear me out because it only require one extra switch block.
SW19 switch, that's 3 position. Center will be off, element can't fire.
In the left position, element enabled and ignores float. Wiring: a NO contact passes voltage to the contactor coil. A stacked NO contact shorts across the float.
In the right position, element is enabled but abides by float position. Wiring: A NO contact passes voltage to the contactor coil.
The LED block can be lit by contactor load side hots but it won't be visually obvious that the float is open or closed. The "element firing" light, or lack of of it lighting would be the indication that the float is not closed.

3. Depending on your level of comfort with the idea of running 120v through the float switch (most are rated for it), the element enable function can be run through the float before hitting the contactor coil. The advantage here is that the element enabled LED, if wired on the load side of the contactor, will alert you when the float is not closed. That is, with the element enable switch position closed, the lack of LED illumination would show the float is not satisfied.
@Bobby_M, thank you for such a thoroughly thought out response. Definitely wasn't expecting this level of investment on your part, but I suspect it's similar to what I do when something's bugging me and I want to figure out the best solution even if it's not my problem. Either way, I'm beyond appreciative of your time and assistance.

In looking at these options I actually like your idea on option 2 for using stacked switch blocks. I would probably need to do it a little differently, however. The float switch I'm looking at, Auber FSW2, can only handle 0.8 A and they say in the description, "Since the switch is rated for 0.8 Amp, a typical wiring is to put it in series with relay (or solid state relay) control loop.", so I'm suspecting I would likely have too much amperage running through it to handle direct switching of the contactor coil (I'm no electrical engineer and might be wrong here). What I'm thinking is still use the three position switch for switching the SSR's DC control circuit, but also stack additional NO blocks on both sides for switching the contactor coil. This way I would not need separate switches for the control of the contactor and switching the DC control circuit for the SSR and the switch functions would happen simultaneously.
 
@Bobby_M, thank you for such a thoroughly thought out response. Definitely wasn't expecting this level of investment on your part, but I suspect it's similar to what I do when something's bugging me and I want to figure out the best solution even if it's not my problem. Either way, I'm beyond appreciative of your time and assistance.

In looking at these options I actually like your idea on option 2 for using stacked switch blocks. I would probably need to do it a little differently, however. The float switch I'm looking at, Auber FSW2, can only handle 0.8 A and they say in the description, "Since the switch is rated for 0.8 Amp, a typical wiring is to put it in series with relay (or solid state relay) control loop.", so I'm suspecting I would likely have too much amperage running through it to handle direct switching of the contactor coil (I'm no electrical engineer and might be wrong here). What I'm thinking is still use the three position switch for switching the SSR's DC control circuit, but also stack additional NO blocks on both sides for switching the contactor coil. This way I would not need separate switches for the control of the contactor and switching the DC control circuit for the SSR and the switch functions would happen simultaneously.

Just for clarification, the reason you stack switch blocks is to keep the circuits isolated. The built in NO block would send the 120v to the coil. The stacked NO block would be closed at the same time, but that one would be dedicated to the 12VDC control signal that would normally go through the float, but in this case would just short across the float like it wasn't there.

The extra blocks are here NO/NC Switch Block for SW15 and SW16 [BK-SW15] - $4.20 : Auber Instruments, Inc., Temperature control solutions for home and industry
 
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Just for clarification, the reason you stack switch blocks is to keep the circuits isolated. The built in NO block would send the 120v to the coil. The stacked NO block would be closed at the same time, but that one would be dedicated to the 12VDC control signal that would normally go through the float, but in this case would just short across the float like it wasn't there.

The extra blocks are here NO/NC Switch Block for SW15 and SW16 [BK-SW15] - $4.20 : Auber Instruments, Inc., Temperature control solutions for home and industry
@Bobby_M, I think you and I are on similar wavelengths. I'm thinking about combining the functionality of breaking the connection with the contactor coil and controlling the SSR's DC control circuit from the same switch simultaneously by adding two additional switch blocks as per this diagram.
SwitchConfiguration.png
 
What program is being used to make these diagrams. I've used SkyCad but it's clunky.
As mentioned in the first post, I use MS Paint. Sure, it’s clunky and basic and it’s a little bit of work to get the connection lines mapped out, but I think I can get a pretty decent diagram done with it. I’m sure there’s probably a lot of better programs to do this, but I’m super familiar with it and maybe more importantly, I’m cheap.
 
Sorry I missed where you said that. Thanks for taking time to answer anyway.

I guess the symbols are the thing. Every program ends up missing the symbol(s) I'm looking for and then I end up trying to figure out their method for creating them. The only benefit to using SkyCad is being able to check your circuits, but they never work due to my makeshift symbols anyway. I think your approach is probably better for just showing people your plan which is all we're doing.
 
Sorry I missed where you said that. Thanks for taking time to answer anyway.

I guess the symbols are the thing. Every program ends up missing the symbol(s) I'm looking for and then I end up trying to figure out their method for creating them. The only benefit to using SkyCad is being able to check your circuits, but they never work due to my makeshift symbols anyway. I think your approach is probably better for just showing people your plan which is all we're doing.
No worries. I tried one other program (can’t recall the name off the top of my head) and it took me longer and frustrated me way more than paint. If you do find something good (and maybe free) I’m interested to try it.
 
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