GFI breaker pricing... this can't be right

[mattd2]

Thank you. I am glad that somebody else also realizes that GFCI's aren't designed to be used as an e-stop. I've tried to point this out before but it never seems to sink in.

I haven't seen Kal's safe-start design but every commercial or industrial installation that I've worked on uses a contactor to break the circuit when an E-stop is hit.

I am on the same side of the fence as you guys but I have brought it up with (I think it was) Kal and he had some valid points for doing it this way. The main one was by tripping the gfci you isolate power back at your breaker box, i.e. your power cord is "dead" as well as the rest of you rig. The thing I don’t like about this is you are relying on something that is always noted on the vendors datasheets that you “should not use the gfci trip as a point of isolation” – but for this situation where you won’t (shouldn’t) be using it to turn the control panel off to work on it it is kind of ok.
The biggest issue I have with the circuit layouts with the GFCI E-stop that are all over the place is what if someone is using it and doesn’t fully understand what they are doing and just blindly following a diagram – i.e. that someone actually might press the E-stop to trip the GFCI so they can rewire a part of their panel, they probably won’t be kill but there is still the slight risk with a huge consequence = high hazard.
I am getting off topic but will just finish off with the following scenarios between a GFCI and contactor E-stop
Contactor E-stop
You see a potential fault/issue on you rig that could cause electrocution, hit the e-stop, you brush against you rig while walking to unplug the power cord, the contactor failed to isolate power so the GFCI trips to save your life….
GFCI E-stop
You see a potential fault/issue on you rig that could cause electrocution, hit the e-stop, you brush against you rig while walking to unplug the power cord, the GFCI failed to isolate power, you get electrocuted….

I.e. by using the Contactor you still have one last line of defence, by using the GFCI you have used you last line of defence.

I’ll stop ranting now

 

[lschiavo]

That's part of why I'm choosing not to use the deliberate-ground-fault method of E-Stop that's common on PJ's schematics. Even good GFIs have a rated number of cycles. Contactors and industrial pushbuttons/selectors have many orders of magnitude more rated cycles.

E-Stops out in the real world aren't done like that, anyhow. Kal's safe-start design with the main power relay is the closest thing I've seen to how we do it at work. I'm doing something similar on mine. I'll draw it up once I've tested it.

Energy isolation is a whole different game. That's where you get into Lockout/Tagout of energy sources. Pretty much every pump in my plant has one of these guys nearby (or something similar):

http://www.grainger.com/Grainger/HUBBELL-WIRING-DEVICEKELLEMS-Disconnect-Switch-2EAV9?Pid=search

Do you have any documentation on GFCI cycle rating? I am not saying you are wrong, I just looked a little on Eaton's site and cannot find any info.

I think the GFCI shunt e-stop is pretty slick but I went with a contactor on mine.

Shunt trip breakers are another option and designed exactly for e-stop situations but I am sure they are more expensive than what most are using.

 

[sdugre]

Even if there was a cycle limitation, how often are you likely to hit the e-stop? I've used mine exactly once, and that was during testing.

 

[passedpawn]

I use something I call a Tetanus Watchdog Online Tester (or tetwatontest for short ). It's a switch that fits into my mouth, tied to a relaxation timer circuit. I need to bite and release once every few seconds. If I don't release, a latching relay is triggered and the whole system shuts down. So, in the event of a "can't let go" electrocution, involuntary jaw muscles clamp down and bingo I brew another day. Pat. Pending.

Or maybe I just have a big ole double pole switch on the wall that kills everything.

 

[lschiavo]

Even if there was a cycle limitation, how often are you likely to hit the e-stop? I've used mine exactly once, and that was during testing.

It's probably not a bad idea to test it before a brew...just in case.

 

[lschiavo]

I use something I call a Tetanus Watchdog Online Tester (or tetwatontest for short ). It's a switch that fits into my mouth, tied to a relaxation timer circuit. I need to bite and release once every few seconds. If I don't release, a latching relay is triggered and the whole system shuts down. So, in the event of a "can't let go" electrocution, involuntary jaw muscles clamp down and bingo I brew another day. Pat. Pending.

Or maybe I just have a big ole double pole switch on the wall that kills everything.

I don't expect any royalties or anything but how can you drink beer with a switch in your mouth? I suggest some sort of device that relies on butt clenching as an input and the frequency should be much higher. You don't want to be electrocuted for several seconds before this things reacts...or a switch on the wall would work.

 

[yjfun]

How about a campfire and big crock pot.

All electrical and propane problems solved.

 

[lschiavo]

How about a campfire and big crock pot.

All electrical and propane problems solved.

Sure as long as you plug your crock pot into a GFI with some sort of e-stop...what's the campfire for?

 

[yjfun]

Gotta dance around something.

 

[bdjohns1]

Do you have any documentation on GFCI cycle rating? I am not saying you are wrong, I just looked a little on Eaton's site and cannot find any info.

I think the GFCI shunt e-stop is pretty slick but I went with a contactor on mine.

Shunt trip breakers are another option and designed exactly for e-stop situations but I am sure they are more expensive than what most are using.

Here's one study from mikeholt's site: http://www.mikeholt.com/documents/freestuff/NEMA-GFCI-Field-Test-Survey-Report-January-2001.pdf

 

[bdjohns1]

Even if there was a cycle limitation, how often are you likely to hit the e-stop? I've used mine exactly once, and that was during testing.

Officially, GFCIs should be tested monthly.

 

[DustBow]

Still thinking about this...on one hand I see your points about GFCIs having a limited "life" or number of cycles so you don't want to use them too much or rely on them for an e-stop. On the other hand, how often do you really use them? It's not like they are the on/off switch - ideally, you would never have a situation where you have to push it.

Then again, you should test the e-stop and GFCI often enough (before every brew?) to make sure they are working and properly protecting you before you start throwing 240v into big steel containers of liquid......
So if you should test your GFCI regularly, you are still putting more duty cycles on it which is shortening its life (in theory)....it all just seems like a circular argument, especially when you factor in the very limited use of these brew rigs compared to an industrial setting (if you brew twice a month, that's still only using these things a couple hours per month)

Would it be ideal to have both options - and E-stop to trip the GFCI and another stop-button to contain the power to the contactor? Seems like tripping the GFCI is actually safer because the GFCI protection should be upstream and that would stop 100% of power from even getting to the control box.

Do they make a mushroom buttom DPST switch that you could just run both hot 120v legs through right at their entry into the panel? Or just use a "regular" DPST switch at the beggining of the wiring in addition to the end right before the element connection?

Sorry for all the questions, not trying to argue at all - just trying to truly understand everything before progressing. I know this is serious stuff. Thanks for all the info

 

[lschiavo]

Here's one study from mikeholt's site: http://www.mikeholt.com/documents/freestuff/NEMA-GFCI-Field-Test-Survey-Report-January-2001.pdf

I didn't read the whole thing. I searched the document for "cycle" and had no results. Can you point me to the section?

Do any manufacturers list a cycle rating for their products like they do for relays?

 

[yjfun]

Its in UL standard 489

http://static.schneider-electric.us...nsulated Case Circuit Breakers/0613DB9902.pdf

I couldn't find anything specific to gfci's or smaller than 50 amps but it looks like UL certification requires 6000 on/off cycles or 50 fault trips.

 

[zeus53219]

Circuit breakers measure life-time expectancy cycles in the thousands, where as quality contactors/relays measure in hundreds of thousands, and some times millions. In industry standards it is not recommended to use any type of circuit breaker as an e-stop. The only benefit I see in doing this is, if the inside of your control panel is saturated in liquid where your incoming power comes in, but if this is the case and your panel is properly grounded the gfci will trip anyway in a harmful situation. Not saying it cant be done, just not recommended in industry. Seal your panel good, ground everything correctly, and place an e-stop on main power contactor for proper piece of mind and longevity of yourself and your components.

 

[passedpawn]

what I use for my 240VAC cutoff:

This (home depot)

inside this weatherproof housing (home depot)

 

[DustBow]

Passed down, I saw that in another thread not too long ago, I think I might have to set up the same thing when I run the 240 line. If something is going wrong during a brew that has me worried, I'd rather reach for that than my (probably metal) control panel.
That will shut off all power before it even gets to my control box or brew rig.

Wow $11, nice:
http://www.homedepot.com/h_d1/N-5yc1v/R-100356941/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=leviton double pole&storeId=10051

 

[passedpawn]

Passed down, I saw that in another thread not too long ago, I think I might have to set up the same thing when I run the 240 line. If something is going wrong during a brew that has me worried, I'd rather reach for that than my (probably metal) control panel.
That will shut off all power before it even gets to my control box or brew rig.

Wow $11, nice:
http://www.homedepot.com/h_d1/N-5yc1v/R-100356941/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=leviton double pole&storeId=10051

I have another one of those on my control panel to just turn off the 240 to the element - leaves the pumps and PID powered.

 

[DustBow]

So you use that instead of a contactor and coil?

 

[passedpawn]

So you use that instead of a contactor and coil?

Yep. Whatcha think about that? I've used it for about 50 batches, still going strong! You can see my box with that switch on it here.

 

[DustBow]

I'm loving that switch, was at HD tonight for other things and took a look, feels nice and heavy. Can't beat it for the price, availability, ease, etc.
I've seen that tool box thread before - very nice. I'm looking at a much simpler build but I still might borrow the idea. HD had a smaller version of that box on special for a cheap price.....