Internal Control Panel Breakers?

[WhiteArmadilloBrewing]

As I've been reviewing a lot of P-Js diagrams for wiring up my control panel I've been noticing additional breakers within the control panel. Is this just for additional protection? I'm asking because if I'm using a spa panel with a 240v GFCI protected breaker and then have the breaker in my main panel behind that then is it overkill to have those internal breakers in addition to SSR's, Contactors, quick blow fuses, etc.?

 

[LittlejohnBrew]

Ironic I've been researching this throughout the day and asked a similar question in my thread. If you search the forums for old posts you will see thoughts vary on this.

From my understanding it is recommended to provide circuit protection for wiring with lower current rating than the upstream circuit protection (usually a 30A circuit breaker on 240v). Say for instance installing a 18 awg wire to you pump that is fed from a 30A circuit. This wire is rated below 30A and in the event it's current rating is exceeded it could cause a fire. So to prevent current exceeding the rating of the wire a fuse or circuit breaker is installed.

That makes sense, but one thing that is confusing to me is that to my knowledge many appliances do not have circuit protection. For instance my KitchenAid mixer has 18 awg rated to 10A yet it's plugged into a 15A or 20A circuit. In my instance I plan to have a 12 awg soow cable rated at 25A from the controller to the heating element on a 30A circuit.

 

[WhiteArmadilloBrewing]

Yeah, I understand that and it makes a lot of sense to me as well. However, I thought I recalled reading in various threads that the relays, contactors, and fuses would all blow/fail before a fire would result from the lower AMP rating of the wire? Maybe I am misremembering this, but I'm not sure...

 

[schematix]

Circuit breakers and fuses (A.K.A Over Current Protective Devices, or OCPDs) are designed to protect wires, not devices. Wires that get too hot can change the atomic structure of the metals. This can cause them to soften and then work their way out of terminals, which can then cause arcing. There's a lot of science that goes into the design of those simple looking screw terminals!

What happens in an overload situation is very much a function of the exact failure mode. There is a huge difference between a dead short and a component drawing 110% more than what a circuit was rated for, but both will cause wires to get hot. Also be aware that wire heating is a function of I^2, so a 2x increase in current leads to a 4x increase in heating. A 100x increase in current leads to 10000x more heating!

It's also important to recognize that OCPDs are not a linear on-off device. There is a time and let thru curve for them. Your 10A fuse or circuit breaker may let 10kA through for some amount of time before it can react.

At the end of the day it comes down to the wire size though. If you buy a pump that normally draws 0.1A, but comes with 14AWG wire, you must have no larger than a 20A breaker (google Ampacity Chart) in front of it to protect the wire. I generally start from the bottom devices and work my way back to the top when determining CB sizes.

For most of the control panels you see here you'll want a main circuit breaker (probably in your houses electrical panel, or spa panel). Then each device should be individually protected based on its wire size.

 

[LittlejohnBrew]

At the end of the day it comes down to the wire size though. If you buy a pump that normally draws 0.1A, but comes with 14AWG wire, you must have no larger than a 20A breaker (google Ampacity Chart) in front of it to protect the wire.

Say you have 10AWG wired to the pump receptacle in your control panel and the external cable wired directly to your pump is 14 AWG do you still install a 20A breaker to protect the exterior cable?

If so what about all the house appliances that have cables with ampacities rated below the circuit that is feeding them?

 

[augiedoggy]

Think of it like this... your main power box has say a 100amp or 200 amp breaker... Below that there are many smaller breakers, each rated for the smaller gauge wire circuits they are feeding (15amp usually feeding 14awg lines 20amp feeding 12 awg lines and outlets).. same should go for our panels. I feed my 55oow elements 23 amps max and am using power wire to feed them thats rated for 25 amps so I installed 25a fuses in my home brewing panel. for my nano panel each element has its own 25amp breaker.

the internal wiring is also protected.. I use a 5 amp fuse to protect the line feeding my DC power supplies even though its 14awg wire going to them because I know the load it should see is less than that.I know this isnt needed due to my power supplies having fuses inside but did it anyway to protect the wiring to them internally.

 

[augiedoggy]

Say you have 10AWG wired to the pump receptacle in your control panel and the external cable wired directly to your pump is 14 AWG do you still install a 20A breaker to protect the exterior cable?

If so what about all the house appliances that have cables with ampacities rated below the circuit that is feeding them?

in this case you should use the size fuse for what the actual outlet is rated for.. its really your choice though. if the only pump you will ever use on the panel is the 14awg one than I would go with a 15 amp fuse.

house appliances either have a warning sticker (like the ones stating this lamp is rated for a 60w max bulb) or an internal fuse within the appliance.
technically the power cord may not be rated for what the breaker is but consider the fact that you also have multiple outlets and devices being powered at once off that same breaker..

 

[schematix]

Say you have 10AWG wired to the pump receptacle in your control panel and the external cable wired directly to your pump is 14 AWG do you still install a 20A breaker to protect the exterior cable?

If so what about all the house appliances that have cables with ampacities rated below the circuit that is feeding them?

There is a wide range of acceptable sizes to use. The most important is that the OCPD is not rated more than the wire it protects.

Couple Examples:

1. 5500W / 240V = ~23A Heating Element -> You always size the OCPD for 125% of the continuous load, so 23*1.25 = 28.6A. Since they don't make a 28.6A breaker, i'd round up to 30A. Since i have a 30A breaker i know all my wires need to be at least 10AWG below it.

2. 1/8HP 120V pump ~0.8A (i'm estimating but close enough). Again, we size for 125% of the load, so 1A. The pump comes with an attached 16AWG cable. So I determine that anything from 1A to 20A is acceptable. Then i can base my decision on other factors, like do i have an unused 5A in my possession? Does the motor have a thermal overload of its own? Maybe i want to give the device some protection (note again though that the circuit breaker protects the wire, not the device) so i choose towards the lower range.

 

[augiedoggy]

While its fine to over build it for this application, Ive been told numerous times that the continuous load rule only applies to circumstances where full continuous load will be applied to the circuit for more than 3 consecutive hours. I dont think anyone will be powering a 5500w element in a home brewery at 100% power for 3 hours. Not for home brewing beer anyways..

To quote clifford power http://www.cliffordpower.com/stuff/...496ba/misc/is_37_80_versus_100_rated_ats1.pdf


"5.0 Continuous Loads:
In Article 100, NEC defines a continuous load as “a load where the maximum current is expected to
continue for 3 hours or more. It is therefore critical to understand that this is a load at its maximum current, uninterrupted for at least 3 hours. Office lighting typically meets this qualification.
OCPD size = 100% of non-continuous load + 125% of continuous load. Sec. 384-16 (c) has the same requirement
except that it is stated in terms of loading of the OCPD. This rule states that an OCPD can be loaded to only
80% of its rating for continuous loads. We should remember that 80% is the inverse of 125% (0.80 = 1 divided
by 1.25) and as such, the rules are indeed identical in their end requirement.
Note!
Read the rule carefully - the 125% sizing of the OCPD (or 80% loading) is ONLY applicable when
continuous loads
are involved. CBs and other OCPDs can be sized at 100% of their rating for any NON-
CONTINUOUS load applications."


A 25a rated circuit will work fine for an element that peaks at 23a and will generally be used in a non continuous pwm or pid controlled application. its worked well for me for years. Ive never had a fuse pop or breaker trip and my wiring does not get hot.

Out of the 5 elements I have only 2 draw 23 amps most end up being a few hundred watts less than the rated size. my HLT element for example is supposed to be 4500w but is actually 4040w peak and draws less than 17 amps peak if I remember right..

 

[schematix]

While its fine to over build it for this application, Ive been told numerous times that the continuous load rule only applies to circumstances where full continuous load will be applied to the circuit for more than 3 consecutive hours. I dont think anyone will be powering a 5500w element in a home brewery at 100% power for 3 hours.

Correct. A continuous load is officially defined as 3 hours. A non-continuous load is sized at 100%.

I went with the 125% because at the time i didn't know how much power i'd need to do things like boiling. Turns out I can maintain a boil on 13G of wort with 40% of 5500W.

 

[WhiteArmadilloBrewing]

Thanks for all the info, I've already been looking at grabbing enough din rail mounted breakers to cover my devices. Looking around eBay I've only seen different AMP ratings with voltage of AC230/400V and can't seem to find a whole lot rated 120/240. Will these breakers work? https://www.ebay.com/itm/CHNT-Singl...ounting-C25-/302663056851?hash=item46781fbdd3

If not, where's a good source to grab what I need?

 

[augiedoggy]

Thanks for all the info, I've already been looking at grabbing enough din rail mounted breakers to cover my devices. Looking around eBay I've only seen different AMP ratings with voltage of AC230/400V and can't seem to find a whole lot rated 120/240. Will these breakers work? https://www.ebay.com/itm/CHNT-Singl...ounting-C25-/302663056851?hash=item46781fbdd3

If not, where's a good source to grab what I need?

Im using these very same breakers in my panel only I got the dual pole breakers since im using it for 240v from what I researched and read these are good for up to 400v.

 

[doug293cz]

...

For most of the control panels you see here you'll want a main circuit breaker (probably in your houses electrical panel, or spa panel). Then each device should be individually protected based on its wire size.

It is not necessary to have a fuse/breaker for each device. You only need to fuse the hots at each point of a reduction in wire diameter (AWG increase.) So if you have a branch off of your 10AWG input, and drop to 16AWG to wire to your pumps, PID's, etc., just fuse at the point where the 10AWG to 16AWG transition occurs. You can usually power everything in your panel, except the elements, with 16AWG wire.

Brew on

 

[schematix]

It is not necessary to have a fuse/breaker for each device. You only need to fuse the hots at each point of a reduction in wire diameter (AWG increase.) So if you have a branch off of your 10AWG input, and drop to 16AWG to wire to your pumps, PID's, etc., just fuse at the point where the 10AWG to 16AWG transition occurs. You can usually power everything in your panel, except the elements, with 16AWG wire.

Brew on

I only suggested it as a best practice since you can also treat them like a switch if you need to for some reason. Also helps with troubleshooting if you do have a problem.

But you are correct - only needed when gauging down. In theory you could run all wires the same gauge as your main feeder wire and be ok. In practice doesn’t work though, which is why there are circuit breakers.

FYI to the OP if you see a UL1077 rated device it’s not a circuit breaker. Looks like one and sort of functions like one, but they are not capable of breaking high current short circuits.

 

[augiedoggy]

FYI to the OP if you see a UL1077 rated device it’s not a circuit breaker. Looks like one and sort of functions like one, but they are not capable of breaking high current short circuits.

Where did you get this information? Please share because thats not at all what I read and not what im reading now... there are different types of breakers like for example a "type d" which have a different curve they are designed to react at but they are all circuit breakers.

 

[LittlejohnBrew]

FYI to the OP if you see a UL1077 rated device it’s not a circuit breaker. Looks like one and sort of functions like one, but they are not capable of breaking high current short circuits.

I was not aware of this and bought a couple Blue Sea Systems 25A push button quick connect circuit breaker. It is listed as UL1077. But based off below would UL 1077 devices be ok? In my instance the main panel breaker UL 489 upstream is rated to 30A and although rated higher than the 25A needed will it adequately protect the 12AWG SOOW exterior cable to element in the event of a short circuit? My thoughts here are that the 30A breaker will see the high amps from the short and trip prior to the high amps reaching the 25A breaker downstream.

"In UL terms, UL 1077 compliant devices are called "supplementary protectors," and are labeled as "recognized components" (not "listed"). They are often called "circuit breakers for equipment" (CBEs). While UL 489 breaker and UL 1077 devices protect against both shorts and overloads, the UL 1077 devices tend to concentrate more on overloads - largely because they are always downstream of a UL 489 breaker."

 

[augiedoggy]

thanks for the infor
In my case, I bought them to be used as breakers for the actual individual elements.

 

[WhiteArmadilloBrewing]

Im using these very same breakers in my panel only I got the dual pole breakers since im using it for 240v from what I researched and read these are good for up to 400v.

I'm also running 30amp 240v to my control panel via a spa panel. My two pumps are 120v, my two elements are 240v, and my RIMS element is 120v. In this case I would need single pole breakers for all the 120v items and dual pole for the two 240v elements, correct?

 

[augiedoggy]

yes

 

[LittlejohnBrew]

I'm also running 30amp 240v to my control panel via a spa panel. My two pumps are 120v, my two elements are 240v, and my RIMS element is 120v. In this case I would need single pole breakers for all the 120v items and dual pole for the two 240v elements, correct?

Hopefully you don't take my posts as derailling yours, but figured mine questions are pretty similar.

Is it ok to put a single pole breaker on each hot line instead of a double pole breaker? Reason I ask is I could not find a double pole breaker that would ship in time so bought two single pole.

I would be going from one 30A UL 489 Double pole breaker->30A GFCI->two 25A single pole breakers one on each hots

 

[augiedoggy]

Hopefully you don't take my posts as derailling yours, but figured mine questions are pretty similar.

Is it ok to put a single pole breaker on each hot line instead of a double pole breaker? Reason I ask is I could not find a double pole breaker that would ship in time so bought two single pole.

I would be going from one 30A UL 489 Double pole breaker->30A GFCI->two 25A single pole breakers one on each hots

I dont believe so, unless theres a way to physically tie the two breaker switches together, otherwise only one pole would trip and you would be left with a potential
brownout condition.

 

[LittlejohnBrew]

I dont believe so, unless theres a way to physically tie the two breaker switches together, otherwise only one pole would trip and you would be left with a potential
brownout condition.

Whats the difference between two single poles breakers one each line vs two fuses one each line? Seems pretty common to do two fuses to the PID.

May be easiest to just cut my losses and replace the 12awg cable with 10awg.

 

[augiedoggy]

Whats the difference between two single poles breakers one each line vs two fuses one each line? Seems pretty common to do two fuses to the PID.

May be easiest to just cut my losses and replace the 12awg cable with 10awg.

240v breaker are designed to break the connection to both hot poles at the same time. if you use 2 separate breakers you have to put a way to tie them together. normally you will see this in a main panel as a pin going through both switches tieing them or a plastic cap. Otherwise, if only one phse trips there would still be 120v going to the faulty device creating a brownout condition hazard potential which can often damage many 240v appliances. In the case of a 240v heating element you would not damage it if this were to happen but if the breaker tripped for a legit reason you would still have power passing through on the other pole.. I dont think it would meet code but im not an electrician either.

That said I have fuses on each pole of my home brewing panel as far as the elements go so yeah I dont know if My situation is any better.

 

[schematix]

It would "work" using 2 1-poles breakers, primarily because you are not using the Neutral wire in this application.

Augie laid out pretty well the hazards. One not mentioned, and probably the main reason i'd use a real 2-pole, is for safety purposes when you shut it off. With 2 separate breakers you very easily give yourself the opportunity to not get both breakers turned off and end up with 1 hot wire.

If it were me i'd always put a 2-pole on any Line to Line circuit.

 

[LittlejohnBrew]

My application I planned to use them not as a main power breaker for the entire controller, but rather to only protect the 12awg wire from the controller to the heating element. So I would only operate them if there was a trip. These are push button designs so I don't even think they can be manually opened/closed, only reset? I assumed if two fuses could be used in this application then two single pole breakers could as well. Sounds like this is better than nothing, but still doesn't beat a double pole breaker.

In any case I went ahead and got 4 ft (guy at Lowe's apparently can't measure and ended up with ~6.5 ft!) of 10awg soow to replace the 12awg. Want to have everything built by this weekend and this was the surefire to have no questions asked on safety during the first brew. Thanks for the feedback guys!