Electrical Primer for Brewers

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

CodeRage

Death by Magumba!
Joined
Aug 22, 2007
Messages
2,209
Reaction score
71
Location
Melbourne, Fl
I've seen a lot of electrical questions pop up lately, many of them frequently asked. So I am going to share what I know and hopefully compile a reference that will answer 99% of the questions out there.

My background is in industrial control systems and system integration. Basically electrical controls for large industrial equipment. I am not an expert on residential power but I am comfortable working with it and understand it's principals. Local building codes may vary so if you are running a new service from your breaker, consult with local codes first.

*I am not going to go through all of the blanket disclaimer mumbo jumbo other than this;
Electricity will kill you dead… QUICK! So respect it.
You and you alone are responsible for burning your house down or causing yourself or others great bodily/mortal harm. So please be careful.
If you have any doubts or questions, put the wire strippers and screw driver down and seek an expert opinion.

Here is a list of important things to understand, know, and apply when working with house hold power and various electrical components of the brewery.

Electrical Fundamentals:
Volts= the potential to do work. Think of it as electrical pressure/psi.
Amps=The amount of electrons flowing through an electrical circuit. Think of it as an electrical gallons per minute.
Watts = Volts * Amps. This is the actual power a system uses.
A few terms:
Service/Supply- Where electricity is coming from
Load – Where electricity is being used/sent to
Line/Leg – one side of a 240 Volt system is usually called a Line or Leg, since there are two separate 120V services one is called Leg/Line 1 and the other Leg/Line 2.

A primer on Residential AC power:
I am going to over simplify this and omit the differences between AC and DC power for the sake of ease of understanding. It is important to note that the two are very different creatures and are not compatible.
Also 240/220 and 120/110 are interchangeable, the actual reading in your home is usually somewhere between those.

Most Residential is what is called a split 240v single phase. By the time it comes into your house from the transformer it is split into three wires and then goes into the circuit breaker.
One wire is 120V(A), another 120v(B), and Neutral. Each of these is attached to its own Bus or Bus bar. A Bus is a piece of metal where you can attach wires and devices (breakers). A fourth wire is brought in and is called Ground. There will be a rod buried in the ground close to the residence with a wire attached to it. This wire is brought into the main panel and attached to the Neutral bus and to its own bus. THIS IS THE ONLY PLACE NEUTRAL AND GROUND SHOULD BE BONDED, from that point on the twain never should meet again.
If you take a volt meter and measure from 120v(A) and Neutral, as well as 120v(B) and Neutral you will read 120 Volts. Now if you measure between 120v(A) and 120v(B) you get 240 Volts. The 120 Volt receptacles in your house are divided up into circuits and then attached to either one of the 120V A/B and Neutral.
For larger appliances like a water heater, dryer, or stove, have both 120v(A) and 120v(B) as well as ground and sometimes Neutral. These are the 240 Volt appliances.
As far as we are concerned, the ground is provided for safety. It provides a path for electricity to flow through in case of emergency. The metal shells of appliances are attached to ground so that in case a wire comes loose and touches the metal. Without this, the next person who touches the shell could have the crap shocked out of them because electricity is sitting there waiting to go somewhere. So, metal rigs and pots need to be well grounded. Plastic containers holding liquid and a heating element should have some kind of ground touching the liquid.
With the metal casing bonded to ground electricity will start to flow causing the circuit breaker to trip turning off the circuit.
This is why we don’t bond Neutral and Ground anywhere else in the house. Since Neutral is used to carry current for 110 Volt circuits you don’t want that current to be attached to anything you may touch.
Hopefully this has demystified the difference between 120V and 240V power, Neutral, and Ground.

Current Ratings and Circuit Protection:
The electrons flowing through a wire or subject to the same laws of physics just like everything else. As the electrons move the encounter friction which creates heat. The amount of friction created is subject to the size wire you use. Imagine two pieces of pipe, one is 1 inch wide and another is 6 inches wide. It is easier to push 1000 gallons a minute out of the 6 inch pipe than the 1 inch pipe because there is less friction. A wire’s AWG or Gauge is the width of a wire and the smaller the number, the larger the wire.
The reason why this relationship is important is that if too many Amps travel through a wire it starts to build heat and could get hot enough to melt/burn the protective insulation off leaving a bare wire. Worse still, the wire could get hot enough to cause whatever it may be touching to catch fire. Here is a table showing the maximum current ratings for the most common sized wires.
AWG/Max Current
14 AWG/15 Amps
12 AWG/20 Amps
10 AWG /30 Amps
8 AWG / 40 Amps
6 AWG/55 Amps

To prevent a wire from getting too hot circuit breakers and fuses are used. These guys sense how much current is passing through a wire and if the current is greater than the fuse/breaker’s rating it will open up, essentially disconnecting the over drawn circuit from power. The size of the circuit breaker or fuse is determined by the size of wire attached to it. So if 14 AWG is used, nothing larger than a 15 Amps breaker/fuse can be used. If 10 AWG were used then anything up to and including a 30 Amp breaker/fuse may be used.
Breakers and fuses are meant to save property NOT LIFE! 1 Amp is more than enough to kill you.
Once the service wire makes it to the brew rig it can be redistributed using smaller wires. The important thing to remember is every time the wire size gets smaller, it needs a fuse or breaker rated no larger than the wires maximum rating.
For example, if a 30 amp services is brought to the brew rig and a circuit for the March pumps needs no more than 15 amps then 14 AWG wire may be used. To do this though, a 15 amp fuse/breaker must be installed between the two. So the 10 AWG wire providing power will go into the supply side of a 15 Amp breaker/fuse and the 14 AWG wire going to the march pumps goes into the load side of the breaker/fuse. The 14 AWG wire is now adequately protected.

GFCI Breakers:
GFCI breakers are designed to control a maximum amount of current like regular breakers but they are also designed to monitor if current is leaking outside of the circuit. Ideally, all current leaving the breaker should return to the breaker after it has been used. When the GFCI breaker sees less current returning than going out, it assumes that current has found an alternate path to ground and trips. The thresh hold for the breaker to trip varies but it is only a few milliamps (0.001 Amps) difference.

DO NOT DEPEND ON A GFCI TO SAVE YOUR ASS! Good workmanship and clean wiring should be your primary means of safety.

Yes, a 240 Volt 2 pole breaker can be used and will maintain GFCI protection if you split the 110. Follow the directions, it will show you how.

Water Heater Elements:
Water Heater elements have 2 parts to their rating. One is Wattage and the other is Voltage.
From these two numbers, you can determine the amount of current (Amps).
Amps = Wattage rating / Voltage rating
Example: A 5500 Watt element at 240Volts will draw 22.92 Amps.
It is okay to run a 240 Volt element at 120 Volts but not vice versa.
Halving the voltage does not halve the Wattage. When halving the voltage the Watt output is divided by 4.
Example: An element rated for 5500 Watts at 240 Volts used at 120 Volts has an actual Wattage rating of 1375 Watts. To determine the current draw, divide 1375 Watts/ 120 Volts = 11.46 Amps.
To run an element at 240 Volts, one terminal is wired to 120v(A) and the other to 120v(B).
To run an element at 120 Volts, one terminal is wired to 120v(A) or 120v(B) and the other to Neutral.

Device Protection: (Added 11/4)
To protect a device, (ie PID Controller, March Pump, Panel Lamp, etc, etc) it needs a dedicated fuse.
There are two main types of fuses, Fast Acting and Slow Blow.
Fast Acting fuses respond very quickly to over currents and should be used on devices that are very sensitive and easily damaged.
Slow Blow Fuses - Have a bit of forgiveness in them when it comes to over currents. They are designed for devices like pumps that have short periods surge current. It takes a sustained over current to cause a Slow Blow to pop.

Fuses should be rated for 125% to 150% of the rated current draw for a device.
Example: March pumps draw 1.4Amps at 120V. A proper sized slow blow fuse would fall some where between 1.4*1.25 = 1.75A and 1.4 * 1.5= 2.1A. So a 1.75 Amp or 2 Amp Slow Blow fuse would be acceptable per pump. Start on the small end and if there are nuisance blows (fuse burns for no real reason) then goto the next size.

Suggested fuse sizes:
PID Controllers - 0.25A Fast Acting (Auber suggests 1A Slow Blow but that is way too much in my opinion.)
March Pumps - 1.75 to 2 Amp Slow Blow.
SSR - For the supply side of the SSR use a Fast Acting fuse equal to or less than the rating of the SSR. Devices being switched by the SSR will need individual fuses should they be protected.

The next installment will be on components used for controlling elements and pumps. If there is any interest that is. Hope it helps.

View attachment Brewery Service And Power Distribution Model.pdf
 
Excellent write up. Look forward to the next installment. I'm sure this will get stickied in the near future.
 
All good points as I have seen it may times on this forum that people attach the ground to neutral at their brew rig vs PANEL ONLY which is by NEC Code. I was hammered about mentioning NEC code many times in the past hence not speaking up about code and becoming silent.
Now one thing you did not mention is many older homes were built with the dryer attaching the neutral to the ground, this allowing 120 volt items like the motor and clock timer to run on 120 volts with a 240 volt feed to the dryer unit with a 3 prong plug vs 4 prong with a seperate neutral.
You should mention derating the cords capacity to the brewing unit due to cord length as well the cords base insulating materials temp ratings.
A 29 year IBEW member.
 
The Neutral wire is the other half of the 120V circuit. Or to be exact each side of the 120V is directly a mirror of the other. Write a wave on a piece of paper, intersect it horizontally at the midpoint. Put a horizontal line under it. Now draw another wave, mirror to the first, under the line. The middle line is the neutral and each wave is a 120VAC circuit. Since it part of the circuit can you see why you should not use it for ground?

BTW electricity is not the flow of electrons. It is electromagnetic radiation, the field that flow creates (the electrons actually go backwards). But it is easier to illustrate electricity as a flow of electrons then to explain it is glowing footballs that you can not see, that really have no height. This is also why you get shocked if you go close to a high voltage line. And this is why you can get electrocuted without actually touching the wire.

But what CodeRage points out are good things to follow. If you do not you could start a fire or shock yourself to death. Keep in mind you are using a liquid (wort) near electricity.
 
The Neutral wire is the other half of the 120V circuit. Or to be exact each side of the 120V is directly 180 degrees opposite and the Neutral equals the 0 point where it crosses. Write a wave on a piece of paper, intersect it horizontally at the midpoint. The top is one 120V the bottom the other and the midpoint your neutral. Since it part of the circuit can you see why you should not use it for ground?

BTW electricity is not the flow of electrons. It is the field that flow creates (the electrons actually go backwards). But it is easier to illustrate electricity as a flow of electrons then to explain it is glowing footballs that you can not see. How far above the wire is voltage, how much is in it (think of dots and filling in the footballs) is amperage.

But what CodeRage points out are good things to follow. If you do not you could start a fire or shock yourself to death. Keep in mind you are using a liquid (wort) near electricity.

Yeah, I omitted the center tap phase shift of the 240V system on purpose. It's a lot of information to cover and for practical purposes here it isn't needed.
You may also want to check your text books on current again. There is hole flow and electron flow, one moves in the opposite direction of the other. The positive to negative system is hole flow. Instead to correct the electron flow, they just called it hole flow. It absolutely is all about the flow of electrons.
What you are describing is induction and have the two confused.

This isn't a place to prove how much some one knows about electrical theory. Just a down and dirty explanation of how to use it for our applications.
 
Brewbeamer,
Hey thanks guy. I know you have pretty exacting standards so a quasi endorsement from you means quite a bit :D. I'll keep those bits in mind on the next installment.
 
Great information! I can't wait to read the next addition. I've been following a lot of the electric rig build threads and it's a bit scary that people are taking on these projects and have no sense of how their electrical system operates. Thanks for this tutorial.
 
Once the service wire makes it to the brew rig it can be redistributed using smaller wires. The important thing to remember is every time the wire size gets smaller, it needs a fuse or breaker rated no larger than the wires maximum rating.
For example, if a 30 amp services is brought to the brew rig and a circuit for the March pumps needs no more than 15 amps then 14 AWG wire may be used. To do this though, a 15 amp fuse/breaker must be installed between the two. So the 10 AWG wire providing power will go into the supply side of a 15 Amp breaker/fuse and the 14 AWG wire going to the march pumps goes into the load side of the breaker/fuse. The 14 AWG wire is now adequately protected.

Great info - one question, if you don't protect the smaller wire to the March pump with a fuse or breaker what are the potential consequences? Fried pump & wire? or Death to brewer standing next to it? I am thinking I need to redo my control box. And do you just put a fuse on the hot lead side after the SSR or at what point?

Thanks
 
This isn't a place to prove how much some one knows about electrical theory. Just a down and dirty explanation of how to use it for our applications.

I should have been more precise. And you are correct. I was attempting to point out why induction can kill as well. It was more about respecting the power then a display of knowledge. I am sorry it sounded that way.
 
Thank you very much for the write up. I think it's an excellent idea for HBT and I think it most definitely should be STICKIED especially if you are going to relate this more to our brewing applications.

However, I am a little confused on one particular aspect, the neutral line. From your description it seems that the neutral comes in from the main service line and then goes into the breaker panel where it is then attached to the "main" ground wire and this is the only area in the house where they meet. I think I have this part correct but correct me if I do not. Where I become more confused is why someone would attach a groundwire to the neutral line at a particular load. Is this ever acceptable and why would you not simply attach the ground to a ground wire? Are people doing this if they did not run a ground wire to their brewstand? Just confused is all.
 
Thank you very much for the write up. I think it's an excellent idea for HBT and I think it most definitely should be STICKIED especially if you are going to relate this more to our brewing applications.

However, I am a little confused on one particular aspect, the neutral line. From your description it seems that the neutral comes in from the main service line and then goes into the breaker panel where it is then attached to the "main" ground wire and this is the only area in the house where they meet. I think I have this part correct but correct me if I do not. Where I become more confused is why someone would attach a groundwire to the neutral line at a particular load. Is this ever acceptable and why would you not simply attach the ground to a ground wire? Are people doing this if they did not run a ground wire to their brewstand? Just confused is all.


I think the this can be an issue if someone installs a sub panel. Panels usually come with a bonding strip (or bonding screw) to bond the ground to neutral bus bar if it is to be used as a MAIN panel. However, as SUB PANEL the ground and neutral should be isolated from each other. This is the case with my current installation in my garage.
 
Scut Monkey:
Ground and Neutral should never be tied together. A while ago it was kind of an accepted practice to use Ground as a neutral, now it is a major violation. If you have neutral bonded to ground any where they need to be separated. The bottom line is the ground conductor should only ever carry current in case of an emergency. Here is something to consider. Say you do have neutral and ground bonded at the device and for some reason the neutral gets disconnected some where else in the system. It should kill power to everything on that circuit. Well the device that has neutral and ground bonded will use the ground instead of the neutral and stay powered up. You know have steady current flowing on the ground through the circuit. Say there is a toaster on that same circuit and it's chassis is attached to ground, will that chassis now has current/potential flowing through it. If something should touch it with less resistance to ground (you are standing on a wet floor in the kitchen barefoot) it becomes the new path to ground and starts to carry all the current. I hope that illustrates the importance of it.

samc,
I added a device protection section, I'll revise it for SSRs here in a second.
 
CodeRage:

Thank you for elaborating. I definitely see how it would be very dangerous to join the ground and neutral. Makes me wonder why it was acceptable in the past. I will have to check my dryer outlet (240V) for safety also in case I decide to go the electric rig route someday. My house was built in 1973 and I believe Brewbeemer stated that they sometimes did this for dryer outlets back in the day. Looking forward to more literature when you have the time to share, thanks again!

- Prosted!
 
My house was built in 79 and the dryer was done the same way. I ran a separate ground all the way back to my main panel and moved the old dryer's ground to neutral.
I believe it was acceptable back then because it was the only device at the end of a dedicated run. Honestly it was done just to save a single conductor. If you do run a separate ground make sure it is at least the same size wire as the service or larger.
 
coderage: I see that you've updated OP; can you highlight additions/edits to make it easier than rereading the whole thing? sorry for being picky but I don't want to miss anything.
 
Brewery Service And Power Distribution Model.pdf attached to OP to illustrate wire gauge selection, wire protection, and device protection.

Can't append to the OP anymore :(.
 
Code Rage,

Thanks for the PDF. It helps to see it drawn out. Two questions however. First, where are you switching to a lesser gauge wire? To me it looks like you are switching to a smaller gauge wire right after the fuses. Second, if you brewstand is a wooden chassis where would be a good place to ground it? Thanks!
 
Yeah, the large gauge wire goes into the fuse/breaker and the smaller gauge leaves the fuse/breaker.

Wooden rigs don't need to be grounded. Anything metal that is some how attached to an electrical device needs to be grounded. Like the chassis of a march pump, a stainless/aluminum kettle with an element need to be bonded to ground.
 
Add a ground screw 1" x #10 minimum size thru a 1" or larger tight knot in the wood then your properly grounded. This I was told when looking at DIY built log cabins at a show a couple years ago, we kind of got out of hand or control.
This above reply is a joke, yup been one one of those days. Sorry brewers.
 
Add a ground screw 1" x #10 minimum size thru a 1" or larger tight knot in the wood then your properly grounded. This I was told when looking at DIY built log cabins at a show a couple years ago, we kind of got out of hand or control.
This above reply is a joke, yup been one one of those days. Sorry brewers.

Thats funny! I'll have to remember that one.
 
Hope the back is feeling better Brewbeemer.

If any one is curious as to what a stop/start station and Emergency Stop looks like here you go...

The E stop button is normally closed, make sure it is the variety that need to be twisted or pulled to reset. Once it is pushed, the R1 circuit will open up causing Relay R1's coil to drop out, which will cause contactors CR1 and CR2 to drop out and kill power to their designated loads.

To start the system the momentary start button is pushed causing Relay R1 to energize. When Relay R1 energizes a set of it's normally open contacts (DPDT icecube relay) close bypassing the momentary start button causing Relay R1 to stay energized with the start button released. This is what is called a latching relay circuit with reset. The E-stop acts as the reset.

Further down you can see the second set of contacts on Relay R1 turns on the coils for contactors CR1 and CR2.
If more than one E-stop button is desired they need to be wired in series.

Mods, can we sticky this or make a link to it from the project list? It's only a few days old and buried 3 pages into the annuls of DIY. I don't mind writing all this stuff up but it is going to take a lot of time and I would hate to see it forgotten and serve help to no one at the bottom of the heap.

* I've attached a picture of an operator interface to run a 1000Hp motor speed controller. You can see the System Start and E-Stop in the upper right hand corner. When the System is on the start button illuminates green as an indicator. Smacking the red mushroom will kill all control power in the panel.

View attachment E-STOP Model.pdf

New Control Interface.jpg
 
I've only found the e-stop/panic buttons at 10a ratings for 250v... what would you use on a system that is pushing 50a at 240?
 
The circuit above only requires a button rated for the current need to drive the R1 relay coil.

R1 drives the contactors which carry the large loads.

To eliminate the need to push the start button to power the system up remove the start button and the R1 contact parallel to it. Basically wire the E-stop straight to the R1 coil.

make sense?
 
CodeRage is on the money exactly what i'm talking about as the contactors holding coil current is very low and no problem for a panic button to handle. Like I mentioned before mounted up front in two locations on your brewery right in your face up front it can be hit, slapped, bumped or banged in a panic and all systems are shut down. I would rather bang a big red panic button than look and flip a TPST toggle switch that alone is not a waterproof hardware store purchased item. You still would need a start button be it mounted on the side of the panic or "E stop" button box out of the way to energize power to your brewing system, the contact coil will not stay energized unless the auxiliary contact is closed to hold the contactors holding coil. This is common in industrial operating equipment as well on switch gear and motor control panels. Like start stop stations we have to work on for a living but not trained for the average home brewer.
You can break any voltage and amperage be it 12KV or 1.2 million volt transmission lines, single or 3 phase 480 volt 80 HP pump motors you name it to open the circuit.
 
The circuit above only requires a button rated for the current need to drive the R1 relay coil.

R1 drives the contactors which carry the large loads.

To eliminate the need to push the start button to power the system up remove the start button and the R1 contact parallel to it. Basically wire the E-stop straight to the R1 coil.

make sense?

You should also mention that this works with a pull to energize "E" panic button and not a red NC stop button that will energize itself instantly after removing pressure on the button so any brewing member doesn't get and install the wrong Red Stop switch button instead.
 
Already did.
"If any one is curious as to what a stop/start station and Emergency Stop looks like here you go...

The E stop button is normally closed, make sure it is the variety that need to be twisted or pulled to reset. Once it is pushed, the R1 circuit will open up causing Relay R1's coil to drop out, which will cause contactors CR1 and CR2 to drop out and kill power to their designated loads."
 
I believe this should be added as a sticky for the sake of added safety for not only electric but gas heated brewing systems with electronic spark ignition systems with PID or other types of controllers like a BCS 460 system.

A back feed from a neutral or hot is just as deadly under the right conditions, hell with the shock only and you live to tell about it. Dry hands on a Fluke 87 meter the readings I had were 400K ohms, wet fingers down to 38K ohms and this would be arm to arm across the chest and heart muscle should you be zapped. You can go into a brown out condition, if lucky and fall to the ground breaking this electrical path thru your body you may live another day, hung up your into a blackout and death not too far behind depending on how long your been energized. hell your 90% water with salt in your system, rather good conductor I would add.
Look at how they treat heart attack people in hospital CCU or ICU units, even static electricity can take out a person with a bad heart after a heart attack. Who knows your own hearts condition as high school basket ball kids have dropped dead on the court not knowing they already had a bad heart condition. A minor 120 volt shock to some people could be your last if you have a bad heart and not know it. You can only die once.
 
Already did.
"If any one is curious as to what a stop/start station and Emergency Stop looks like here you go...

The E stop button is normally closed, make sure it is the variety that need to be twisted or pulled to reset. Once it is pushed, the R1 circuit will open up causing Relay R1's coil to drop out, which will cause contactors CR1 and CR2 to drop out and kill power to their designated loads."

How is this different than a simple 2-pole (DPST) switch?
 
How is this different than a simple 2-pole (DPST) switch?

If you are gating all of the power through the DPST switch it is easier to find a contactor or relay to to handle such a large current.

Now I can hear your self ask "Why don't I just drive R1 with a DPST switch?"

Well, you could. The idea is it is easier to hit a mushroom than it is to flip a switch.

Also, you CAN use a momentary stop button instead of a maintained one. When you see a stop/start circuit it usually does have a momentary stop button. This is so the operator can quickly press the momentary button to stop and start the device as needed with out an extra operation like a pulling the mushroom back out to restart it.
The E Stops are wire in series with stop button. This is done so if an emergency occur outside of the view from the operator's station and an E-stop is pressed at one of these locations, the operator can not restart the device until that E-Stop has been reset.

For example, a couple hundred yards down the bottling line of your favorite micro brew, the conveyor that feeds the bottles from the conveyor to the capping machine gets out of sequence and bottles start to spill on the floor. The guy by the capping machine sees this and hits the conveyor E-stop to stop the conveyor. The conveyor operator, oblivious to the problem at the end of the conveyor, is screaming WTF and repeatedly mashes the start button to restart it but it won't work. By this time the shop foreman is chewing peoples' butts to get the problem fixed. Then the E-Stop button is reset.

That stop/start circuit is a staple in industrial controls and was primarily designed to support momentary push buttons. Why momentary buttons? I have no clue, perhaps they are mechanically simpler which makes them less prone to wear and more reliable.
Edit:
I also forgot, you can put start/stop buttons in multiple locations and not have to worry about coordinating the position of multiple maintained switches. Starts are always wired in parallel to each other and stops are ran in series. The stops being normally closed of course, pushing them cause the contacts to open. This is probably the reason why momentaries are preferred.
 
If you are gating all of the power through the DPST switch it is easier to find a contactor or relay to to handle such a large current.
I got one that looks just like the one on your wall from Home Depot. Maybe $10. 2-pole 30A, perfect for this.

I also forgot, you can put start/stop buttons in multiple locations and not have to worry about coordinating the position of multiple maintained switches. Starts are always wired in parallel to each other and stops are ran in series. The stops being normally closed of course, pushing them cause the contacts to open. This is probably the reason why momentaries are preferred.
Now that is a good point. Not a biggie in my setup, but when I go BIG I'll consider the multiple, paralleled, momentary kills.
 
Now that is a good point. Not a biggie in my setup, but when I go BIG I'll consider the multiple, in series, momentary kills.

Fixed it for yah :)

Im not saying that people HAVE to do this. This circuit was brought up in another thread by some one else and wasn't explained. So instead of folks scratching their heads, I put it here so it can be seen and understood.
Whether some of these things are practical for the average guy is on an individual basis. Hell, you can wire nut two wires together for all I care (actually I do, so please don't).

These are industrial control practices meant and have been developed and refined since electricity was introduced to industry. When Brewbeemer talked about a stop/start circuit and I drew one up and it was exactly what he was talking about with no collaboration. Considering he is retired, I am only 5 years into my career, and that he never agrees with any one :p says something. It's just a standard and proven way of doing things.

I don't have an E-Stop on my system, I used a switch to drive a contactor. My next iteration will probably have one on the control panel.

When I have to design things like this as a rule I have to limit the length of large current carrying conductors. Mainly because they induce a lot of electrical noise and bringing it into a control panel with sensitive instrumentation is a no no, especially if there is no real reason for it being there.

Say you are pulling 20 amps through a wire feeding a heating element. That wire happens to run parallel several inches to the trigger wire for your SSR. At those currents it could easily induce enough voltage to cause the SSR to close without the PID telling it to. The design of the driver circuit in the PID controller will affect how susceptible it is to this but none the less it creates an opportunity for a misfire. I use shielded analog wire to trigger my SSRs as an extra precaution against this.

I don't know if you are trying to tell me I am wrong, want to understand why, or looking for an argument about using a wall switch instead. This is just information put out there for people to draw from if they need to. Im not trying to prove anything. ;)
 
I don't know if you are trying to tell me I am wrong, want to understand why, or looking for an argument about using a wall switch instead. This is just information put out there for people to draw from if they need to. Im not trying to prove anything. ;)
I don't want to argue, and I am not telling you you're wrong. Just pointing out that there is a cheap switch easily available that will do the job. I thought that would be useful. Hmmm.

I REALLY don't want to argue.
 
Back
Top