Need Help Reviewing Electrical Diagram

Bobstin · Sep 17, 2013

Hi all,
I've been brewing for a while, and finally decided to make the jump to electric brewing - I've gotten to the point where I think that I should be good to go, but I was hoping that someone with more experience could take a look at my wiring diagram before I turn it on.

The setup is a single PID, single (240V) heating element with one pump.

Any help would be appreciated!

Thanks,
Bobstin

abarnett · Sep 17, 2013

What's going in to line 2 of the PID? Is that a fuse on the neutral?

SkullStacheBrew · Sep 17, 2013

This is almost the same wiring as my new system except I'm using an Arduino in place of the PID to control the heating and pump. I have a few suggestions.

If you have not already purchased the switches, you do not need to connect both sides of the contactor coil through the switch. You can connect the one side permanently and then simply use the switch to activate the coil. It will only save a few bucks but it's something. Also you don't really need 240V coil contactors, 120V will do the same but again, this is only if you have not purchased them and want to save money.

The indicator for the heat should not be plugged into the coil. Doing this will illuminate the light whenever you have the switch on regardless of if heat is being applied. I would tie it to L2 that is going into the heating element. This way, if the PID is turning the element on, the light will go on.

I am also confused about pin 2 on the PID. Usually the fuse goes on the hot side.

Be careful using different size wires. I would have a breaker attached to L1 after your first contactor that is appropriately sized and powers the pump and PID using the correct wire size for the breaker.

For the fuse on the pump. I am assuming you are using a March or Chugger pump. These generally draw 1-1.2A so a 10A fuse may be a little large to protect it. I am using a 2A slow burn fuse. This allows the pump to draw a little more current upon start up without blowing the fuse but protect it against damage if the current draw is above 2A for a continuous period of time.

I'm not sure why everyone likes to use the emergency buttons wired the way you do. I have seen it many times and it is on almost all of the wiring diagrams on here. If you are using a contactor to provide the power for the panel, why not use the emergency stop button to cut power to that? I have mine wired in series with the main on/off switch. It is a normally closed button and when pressed, the contactor is disconnected and power to my panel is cut off.

Those are some of my suggestions. I see no reason why it would not work the way you have it, but if you want to save a little money and protect it a little better in case something goes wrong I would make those minor changes. Good luck! Be sure to post pictures when it's all done.

Bobstin · Sep 17, 2013

I'll definitely move the fuse to the hot side of the PID, as well as tie the heat indicator to the L1 of the heating element. I'll also look into the expected draw of the pump.

My plan was to use 10 gauge wire for the bolded connections, and 18 gauge for the others. Does that make sense?

Unfortunately, I already have the contactors, so it looks like the switching is going to have to stay the way it is. It's actually more of a hassle in the diagramming than it is in real life, which is nice.

My understanding is that the way the E-Stop is wired, it will trip the GFCI breaker in the wall when pressed; if I hook it up to the first contactor, isn't it the same as if I switched the main power switch?

I'll make sure to upload some pictures when all is said and done

Thanks everyone!

Bobstin · Sep 17, 2013

Sorry, but one more question: Given that I am rerouting the heat indicator light to the L1 of the output, does it make sense to do the same to the power indicator light?

SkullStacheBrew · Sep 17, 2013

You can switch the power indicator light if you want. That one will work the same in either position unless your contactor fails. If that happens, the light will come on even if no power is going through in the current design.

Yes, the GFCI will be tripped when the E-Stop is pressed. I guess it will protect the panel better but I found it easier to just wire it up in series. I'm using a keyed switch for my main power and hitting a mushroom button is faster than turning a key, but just barely.

The wire size makes sense but you need to make sure the wire size does not change until after the fuse. There is still 30A that could go through the 18GA wire and burn it up unless there is a fuse or breaker protecting it. That's why I suggest a 6A breaker or something similar so that you can use smaller wire after the breaker and not have to worry about starting a fire if something goes wrong. Again, this is only if something goes terribly wrong but it's better to spend a few extra bucks and wiring time than to have to rebuild the entire thing if you burn out the wiring.

For example, this is mine:

It's a little hard to see but the first set of breakers are 30A and then a 15A breaker second. The thing on the third SSR is a 120V alarm.