Check my wiring?

Hey all,

So I've been mightily inspired by JKarp's Countertop Brutus, BK's Simple Brewery, etc., and am looking to build a similar system. For ease and transportability, I'm keeping it 120v, and using two elements (2000W and 1500W), using one 20A circuit and one 15A circuit. I'm trying to fit everything into a single toolbox (a la BK). I know the wiring here is relatively simple (i.e. no resistors or capacitors or other wacky stuff), but I want to make sure I have everything right before I start building!

Anyway, here's what I have. Apologies for the messiness. I did it on Google Drawing (because, well, that's what I've got). I know it's not very schematic, but I tried to lay it out like the toolbox will be laid out - top of the frame is the back of the box, bottom of the frame is the front, sides are, well, the sides.

My sense is that I've got most of it, but wanted to make sure I got the little things right - fuses, LEDs, etc. Also, does it matter whether I use bus bars or terminal blocks? I have this drawing using both, but if there's an advantage to using either I'm totally willing to go with it.

Any and all suggestions from the brilliant minds here would be super helpful!

I seem to recall reading that one of the resident electrical guru's thought that mixing electric from different sources in the panel was a bad idea. Not sure of the exact reasons although on the face of it I would have some concerns, but not sure how to state them.

Palefire, you can use 1 bus bar for the ground and three terminal strips for the two hots and one neutral. Everything metal should be bonded (grounded) together (brew pots, toolbox (lid and base), metal frame, etc.), this way they're all at the same potential (zero volts) if anything goes wrong. It would probably be better if you used 2 20A circuits and a 2 pole 20A breaker (GFCI for extra protection). This way, you can use the same gauge wire for everything. Any of the devices will be fused as well. At the panel; A 20A 240VAC GFCI breaker to a 20A 240VAC single receptacle (this could be mounted to the panel with an offset and a “handy box” http://electrical.hardwarestore.com/14-45-electrical-boxes-metal/handy-box-238329.aspx . Power to the tool box via 12/4 SJ cord with a 20A 240VAC male plug. 2 schools of thought on the type of wire within the toolbox; use solid THHN/THWN. It makes your job look neater but is a PITA to work with. Stranded THHN/THWN, easier to work with, but can make your work seem sloppy. My feeling, the toolbox will be staying closed for 99% of the time. I’d also use insulated wire for the ground.

petey_c said:

Palefire, you can use 1 bus bar for the ground and three terminal strips for the two hots and one neutral. Everything metal should be bonded (grounded) together (brew pots, toolbox (lid and base), metal frame, etc.), this way they're all at the same potential (zero volts) if anything goes wrong.

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Cool, good to know. I was definitely planning on grounding everything metal.

It would probably be better if you used 2 20A circuits and a 2 pole 20A breaker (GFCI for extra protection). This way, you can use the same gauge wire for everything. Any of the devices will be fused as well. At the panel; A 20A 240VAC GFCI breaker to a 20A 240VAC single receptacle (this could be mounted to the panel with an offset and a “handy box” http://electrical.hardwarestore.com/14-45-electrical-boxes-metal/handy-box-238329.aspx . Power to the tool box via 12/4 SJ cord with a 20A 240VAC male plug.

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I totally see how this would be an advantage, but honestly, I'm not interested in messing with my panel. I already have a dedicated 20A GFCI outlet and a few dedicated 15A GFCI outlets I can use. Plus if I keep it 120V I can keep the thing portable and brew at other people's houses, etc. Also, I'm sort of stretching my brewing budget to build this thing anyway (by "brewing budget" I mean "money that SWMBO will allow me to spend on brewing"), so I'd rather not go about adding further cost to it.

Though I will probably use the same gauge wire (12 gauge) for everything anyway, just in case I want to upgrade one day.

2 schools of thought on the type of wire within the toolbox; use solid THHN/THWN. It makes your job look neater but is a PITA to work with. Stranded THHN/THWN, easier to work with, but can make your work seem sloppy. My feeling, the toolbox will be staying closed for 99% of the time. I’d also use insulated wire for the ground.

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Yep, I totally hear you. As long as it's reasonably organized, I don't care too much how sloppy it seems, assuming it's all done safely, of course.

Thanks for the advice!


Oh, and given all of that, does my diagram still seem right (anyone)? Thanks again for any help anyone can provide!

Bumpsky, bumpsky ... anyone? I just want to make sure nobody gets electrocuted here. Or that I don't ruin any of the electrical pieces I buy.

Thanks in advance ...

What is the purpose of the 15A and 20A fuses inside your control box if the power sources are already coming from wall outlets controlled by 15A and 20A breakers?

I mean, the diagram looks ok to me, but I was just wondering about this bit of redundancy in the design.

petey_c said:

Palefire, you can use 1 bus bar for the ground and three terminal strips for the two hots and one neutral.

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No, you cannot do this, if I understand what you are saying. If you are feeding the box with 2 separate 120V GFI sources, you need to keep the neutrals from those two circuits separated. Ground can be shared, but neutrals need to be isolated or you will have your GFI protection tripping.

Walker said:

What is the purpose of the 15A and 20A fuses inside your control box if the power sources are already coming from wall outlets controlled by 15A and 20A breakers?

I mean, the diagram looks ok to me, but I was just wondering about this bit of redundancy in the design.

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Great, thanks - this is exactly the sort of help I was hoping to get. I honestly don't know why there's that redundancy. I was loosely copying Boerderij Kabouter's schematic, and he has those fuses in there. So I figured there must be a reason I didn't know about! But yes, they'll be coming from breakers, so I guess there's really no need.

No, you cannot do this, if I understand what you are saying. If you are feeding the box with 2 separate 120V GFI sources, you need to keep the neutrals from those two circuits separated. Ground can be shared, but neutrals need to be isolated or you will have your GFI protection tripping.

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Yeah, this seemed a little weird to me, too. I'm no engineer, but I've always thought that you wanted as much power (EDIT: "current," that is - like I said, I'm no engineer) coming back in as you've got going out ... having 15A (say) going out of an outlet and 35A going back into it didn't seem quite right.

Thanks much for the help!

Palefire said:

Great, thanks - this is exactly the sort of help I was hoping to get. I honestly don't know why there's that redundancy. I was loosely copying Boerderij Kabouter's schematic, and he has those fuses in there. So I figured there must be a reason I didn't know about! But yes, they'll be coming from breakers, so I guess there's really no need.

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I'm not saying it's a bad thing. I'm sure I've looked Kabouter's schematics at some point, but I don't remember the details of everybody's system (except my own. ).

It might be possible that they had a main feed of 30A or 50A or something coming into the box and then used fuses to create separate lower current "zones" in their designs. I do that with mine. 240V/50A comes in, and is reduced to one 240V/25A zone and another 120V/15A zone via some mini circuit breakers in my panel.

But, if you are feeding with 20A and you need 20A to some items, then a fuse isn't really necessary.

The smaller fuses to protect the pump and PID are good ideas. I didn't put them in my system, and I keep meaning to do it, but I just haven't opened the box up to do the work.

Palefire said:

Yeah, this seemed a little weird to me, too. I'm no engineer, but I've always thought that you wanted as much power coming back in as you've got going out ... having 15A (say) going out of an outlet and 35A going back into it didn't seem quite right.

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Yeah, that's exactly the kind of thing that will trip GFI circuits. Input current and output current have to be the same, or something is not right and it cuts the flow.