Circuit breakers vs supplementary protectors

[EuBrew]

I'm wondering if I made a $100 mistake. My brewing panel has been done for some time so now I'm working on my panel for a fermtroller and noticed I have both kinds of "breakers" in my brew panel.

Are the supplemental protectors OK to use in my brew panel? All my single pole breakers are the circuit breakers but somehow I ended up with the supplemental protectors on my double pole, 2 30A and a 20A probably because they're half the price.

Anyone have any input on whether theses need changed out or not?

The circuit breakers are UL 489 rated shown below

http://http://www.automationdirect.com/adc/Shopping/Catalog/Circuit_Protection_-z-_Fuses_-z-_Disconnects/UL_489_Miniature_Circuit_Breakers/Double_Pole_Mini_Circuit_Breakers_(0.5A-40A,_WMZT2_Series)/C_Curve_(0.5A-40A,_WMZT2Cxx)/WMZT2C30

The supplemental protectors are UL 1077 shown below

http://http://www.automationdirect.com/adc/Shopping/Catalog/Circuit_Protection_-z-_Fuses_-z-_Disconnects/UL_1077_Rated_Supplementary_Protectors/Double_Pole_Supplementary_Protectors_(0.5A-63A,_WMZS2_Series)/B_Curve_(6A-63A,_WMZS2Bxx)/WMZS2B30

 

[sandyeggoxj]

I used the wmzs1 and wmzs2 ul1077 breakers in my panel. The whole panel is connected to a primary circuit breaker at the main panel. The breakers inside my control panel are basically just a reset able fuse for each appliance, or heating element/pump. I have one 115vac single pole ul1077 breaker for all of my 115vac accessories. This allows me to step the wiring down from 6gauge to 14 gauge for the low amp stuff.

 

[schematix]

1. The main function of a Circuit Breaker or fuse is to protect the wire in the event of an over current. One or the other must be used any time wire sizes are stepped down (if you want to build to code).

2. UL1077 devices aren't really circuit breakers - they are supplementary over current protective devices. They are kind of like a CB, but aren't a true CB. They aren't built as rugged and aren't as capable of breaking large fault currents. You can't use these to step down wire size if you want to build to code.

3. I am an electrical engineer, and I knowingly used UL1077 devices in my panel instead of true UL489 breakers due to cost. I'm not saying you should do it, but I felt comfortable it was an acceptable substitution given my operating conditions. I would NEVER do this in an industrial control panel though. Should I ever trip the device due to over current I will replace it and quite likely replace the wiring too.

UL489 = Circuit Breaker
UL1077 = Supplementary Over Current Protective Devices (not a circuit breaker)

 

[Facinerous]

To further schematix explanation. If you have a serious fault the UL1077 device may not be able to break the fault current, but your panels breaker will. The UL1077 device will, on the other hand, be able to break lesser fault currents and should trip first before your panels breaker.

So if you have a small problem, where your overcurrent amperage is maybe above or 5 times the rated amperage of your supplementary device it will operate and break the current making things safe. If you have a major problem and your overcurrent amperage is in the thousands of amps, like 10K, then your panels circuit breaker should take care of that.

Thats the way I see things.

 

[schematix]

I mostly agree with Facinerous additions. A slight overload doesn't pose much of a risk to either device. However, a significant overload (e.g. full short circuit) could potentially result in the UL1077 breaker exploding before the main breaker opens.

However, it's really hard to say exactly what would happen without knowing the short circuit current available and the trip curves for each breaker. The only thing really limiting the current is the resistance in the supply transformer secondary, and your wire. Neighborhood transformers tend to be small though and couldn't supply tens of thousands of amps even in a short circuit. When you get to an industrial setting where you might be supplied off a local substation, it's quite easy to have hundreds of thousands of amps available, and it can release energies on the order of TNT within milliseconds. See google or youtube for 'arc flash'.

This is a very expansive subject and there is a lot of information available online if you google 'UL489 vs UL1077'. Bottom line is that to do it right and be guaranteed of a set up that can interrupt a high fault current you need to go all UL489. Realistically that might be overkill, but electrical standards are written to be nearly fool proof.

Additional $0.02: UL1077 devices should be mandated not to resemble circuit breakers because they are commonly misused as such.

 

[EuBrew]

Thanks for all the responses! I should insert the obligatory "hold harmless declaration" here. I guess the good news is people that know more than me have done the same. I'm properly GFCI protected with a 50A GFCI fed from the abandoned 50A breaker in the house panel left from moving to a gas range.

The only thing that leaves me a little leery is the ones I used the UL1077 are my elements. They are all properly grounded so there's that to feel good about. I have my system set up so they can't dry fire (unless I do it manually).

I guess the long and short of it is if I ever have an extra hundred bucks laying around (which is unlikely since we found out Monday we're having twins) I'll replace them with UL489's and I'll spend the extra 40 bucks on the 489's up front when building my fermtroller.

 

[schematix]

Congrats on the twins. Yikes!

The fact that it's grounded, or that you have a GFCI is irrelevant. Those are solutions to different problems.

A dead short can draw many thousands of amps during the first fraction of an AC cycle. Both your UL489 and UL1077 devices are designed to open the circuit when instantaneous current exceeds a certain multiple of its rating. Should you have a large current source available, the actual amperage may reach into the thousands for some period of time (we're talking milliseconds to high microseconds now). If there is too much current flowing, the UL1077 may not be able to open the circuit before self destructing (along with other things). Your upstream breaker will eventually open the circuit, but not before something else downstream has had an uncontained failure (note: this is essentially a bomb going off in your panel).

Those are the risks.