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AFCI or GFCI outlet paired with breaker


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02-11-18, 12:06 PM   #1 (permalink)  
AFCI or GFCI outlet paired with breaker

I understand that AFCI and/or GFCI breakers render their outlet counterparts useless. But for various reasons that I’d rather not go into it here, I want to have them working together.

I have one very simple question, is there anyone who actually have seen this in real life working and can comment on the trip order, i.e if an outlet trips, will the breaker also trip OR just breaker trips and not outlet? This is not an opinion post, I understand majority will say its waste of money. I m here for real world experiences.

I would like it so that only the portion of the cable between the breaker box and first outlet be protected by the breaker and breaker only trips if there is something wrong in that portion and for rest of the circuit an outlet tripping should be localized to that outlet OR very close to that outlet (close enough so you can hear it) from a downstream outlet.

In theory, this should work but in practice I m not so sure.

 
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02-11-18, 12:55 PM   #2 (permalink)  
There is an engineering term for the order in which fuses/breakers trip. "overload coordination". You would typically want the closest overload protector to trip, not the one further upstream. To do this, you need to find out the trip curves of each. And if a GFI/AFCI type, the fault current.
Long story short, you want a 30ma breaker and a 5mA recept. Even then, if, let's say, a 100mA fault develops, you need to understand the time curves of each to prove the local breaker will trip and not the panel breaker.

 
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02-11-18, 01:03 PM   #3 (permalink)  
There is really no way to determine which device will trip at any given time. It has to do with where the device is located and the given time of the waveform during the fault. You would think that the closest GFCI would trip before one further away, but it real conditions this is often not the case. I have personally seen items trip much further away from a fault before a closer one and vice versa.


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02-11-18, 01:42 PM   #4 (permalink)  
Thank you, that makes sense. How do I find the trip curves for these outlets/breakers? Its not in the manual for each.

 
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02-11-18, 02:09 PM   #5 (permalink)  
You could attempt to ask the manufacturer of each. trip time vs various ground fault currents. I would be more inclined to run the experiment. The cost of the items is quite trivial.
I'd maybe use a 5, 30, 100mA ground load with both devices in serial and start recording which one trips first. You don't actually care the trip time, you just care which trips first, correct?

 
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02-11-18, 02:16 PM   #6 (permalink)  
Posted By: telecom guy You could attempt to ask the manufacturer of each. trip time vs various ground fault currents. I would be more inclined to run the experiment. The cost of the items is quite trivial.
I'd maybe use a 5, 30, 100mA ground load with both devices in serial and start recording which one trips first. You don't actually care the trip time, you just care which trips first, correct?
All I care is the following:

I have pretty long and spread circuits (1 circuit has 8 double outlets, 10 lights for example). Because of their location, all of these are individual GFCIs wired in parallel. I want the GFCI outlets to protect the outlets only and the breaker to protect any damage between outlets as well as the first outlet and the panel. I want the breaker to be a safety net/last resort.

Another thibg is troubleshooting. Yes I could have no GFCI outlets and have 1 breaker but then how the heck do you knoq where the problem is? If above works, i ll know exacfly which outlet and if no outlets trip I will say its the cables.

Also besides the above case, for example in my kitchen I have series of outlets already on GFCI. But the 20 some feet old cloth cable that runs from panel to first afci/gfci outlet is unprotected. Do you see my point? I want whatever trips upstairs ro be resettable locally and only godown to the panel if there is a genuine problem (like an actual rapture in a cable due to nail etc).

 
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02-11-18, 02:23 PM   #7 (permalink)  
All GFCI devices that are used for protection of personnel (pretty much all DIY installed GFCI devices) are required to trip between 4 - 6 milliamps. Testing each device will likely required some fancy testing equipment.


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Last edited by Tolyn Ironhand; 02-11-18 at 04:09 PM.
 
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02-11-18, 02:29 PM   #8 (permalink)  
Hit the test button on each of the recepts. one by one. There, you have just done one of the required tests.

 
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02-11-18, 02:42 PM   #9 (permalink)  
What I didnt meantion is the breakers wont arrive for 10 days so thjs is all my speculation/curiosity coming here asking

What I did do though is to install 1 AFCI/GFCI combo outlet at the top of that entire circuit I mentioned and when I press the test button of any outlet OR use a gfci tester, the main AFCI/GFCI outlet trips first and the actual outlet being tested NEVER trips. Now that is what I dont want happening.

The outlets I installed are all leviton 20amp WR/TR outdoor rated GFCI and the AFCI/GFCI one is regular TR if that makes a difference.i am hoping a breaker will be less sensitive and not trip before the outlet.

 
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02-11-18, 03:28 PM   #10 (permalink)  
I think you will be disappointed. | Consulting-Specifying Engineer

At least 4 categories of GFCI breakers and you likely are only going to see Class A (6mA trip) for your panel. A class C trips at 20mA. But, even then, that is no guarantee that the class C would not trip first, if, say, a 100mA fault current develops.

 
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02-11-18, 03:52 PM   #11 (permalink)  
Posted By: telecom guy I think you will be disappointed. | Consulting-Specifying Engineer

At least 4 categories of GFCI breakers and you likely are only going to see Class A (6mA trip) for your panel. A class C trips at 20mA. But, even then, that is no guarantee that the class C would not trip first, if, say, a 100mA fault current develops.
This is the one I bought : https://www.homedepot.com/p/Siemens-...0DFP/205488018

How can. I simulate 100 mA? All I have is gfci tester.

 
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02-11-18, 03:57 PM   #12 (permalink)  
1200 Ohm resistor. Not simulated, real! Do a little test jig with a SPST switch and the 3 wire plug, using only the Line and ground. Note the power limitation of whatever R you choose vs the exposure time at 120V.

 
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02-11-18, 04:09 PM   #13 (permalink)  
Again, pretty much all GFCI devices you buy in the store will be for personnel protection. They will all have the same 4-6mA trip rating.


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02-11-18, 04:45 PM   #14 (permalink)  
IT seems like given how technologically advanced we are, in this stuff, we are actually in dark ages. In this day and age, there has to be a way to diagnose/control any given part of a circuit or lets just call this any “sub circuit” without jumping through all these hoops. Otherwise we are severely limited in our true ability to design and build these systems the way we want. How the hell is anyone supposed to know which piece of cable between which outlets and/or light fixtures buried somewhere behind a wall has damaged insulation causing the arc protector to trip WITHOUT having to dismantle 20 boxes and doing guesswork? My entire point of doing this was to isolate problems IF they happen

My background is in computer science and I am honestly apalled how some of this stuff is so old technology. Its like literally everything from cars to internet to tvs to appliances are in a new “era” but electricity and anything electrical based stayed still making very small increments. Everything from how you wire an outlet to switch boxes is so error prone and old technology. I mean the entire afci/gfci thing is so simple for example, one would expect this to be invented and widely used 50 years ago. If I pulled 100 people from the road, 99 will say the circuit breaker (a regular one) will trip if a person is electrocuted. But you are telling me a circuit breaker will only trip if its in a overcurrent situation. Meaning, there is no protection whatsoever in my home against electrocution all these years! Knowing what I know now about electricity and how error prone things are and how fragile components are, I’m telling you everyone of us homeowners is sitting on a pile of dynamite when we navigate around yards of romex cables in our basements or cut up walls. You can easily kill yourself or burn your house down. Its like in every area we are so advanced but in this, not so much.

You know how airplanes have systems after systems building redundancy? They basically have 4 altimeters, 3 air speed indicators etc and even if you purposedly try to crash land a plane, it will warn and alarm in so many ways and I would expect a lot more advanced tech with electricity.

I want to say I m sure there is good reason why things are the way they are but I dont know

/Rant over:P

 
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02-11-18, 04:46 PM   #15 (permalink)  
Yep, right there on the label. Class A.

Triple airspeed indicators? Google AF447

 
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02-11-18, 04:59 PM   #16 (permalink)  
Posted By: telecom guy Yep, right there on the label. Class A.

Triple airspeed indicators? Google AF447
Lol I know but you got what I am trying to say. This stuff is so basic, these devices should be able to work with each other OR they should make other helper devices that can synchronize with the breaker which you could mount to a regular outlet. The entire point is to isolate the problem AND restore service to the rest of the circuit (if possible, i.e if all are prallel).

 
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02-11-18, 05:20 PM   #17 (permalink)  
Well, I like point of use GFI's also. I have no GFI's in the load center. And, I don't even like to string out the LOAD wires. This house had a garage GFI feeding an outdoor recept many dozens of feet away. Same for several bathroom recepts, fed from a mystery source. GFI recepts are low cost.

In industry, you will (should) find recepts marked with the load center and the circuit number for easy reference. Can't say I've seen homes with that, but you COULD.

 
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02-11-18, 06:16 PM   #18 (permalink)  
Posted By: telecom guy Well, I like point of use GFI's also. I have no GFI's in the load center. And, I don't even like to string out the LOAD wires. This house had a garage GFI feeding an outdoor recept many dozens of feet away. Same for several bathroom recepts, fed from a mystery source. GFI recepts are low cost.

In industry, you will (should) find recepts marked with the load center and the circuit number for easy reference. Can't say I've seen homes with that, but you COULD.
Do they make AFCI breakers that are not “combination”, i.e no ground fault detection? I cant find any for siemens Q type. Because maybe what I need is basic AFCI.

 
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02-11-18, 06:40 PM   #19 (permalink)  
Combination means overload plus various types of Arc fault.
Dual function adds GFCI.

http://w3.usa.siemens.com/us/interne..._DS_CAFCI2.pdf


Last edited by telecom guy; 02-11-18 at 06:46 PM. Reason: fixed the combo part.
 
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02-11-18, 07:04 PM   #20 (permalink)  
Posted By: telecom guy Combination means overload plus various types of Arc fault.
Dual function adds GFCI.

http://w3.usa.siemens.com/us/interne..._DS_CAFCI2.pdf
I thought combination meant Arc protection plus smaller ground fault detection (20mA instead of 6mA). Is that not the case?

Do they make a breaker that only protects for arcs and nothing else?

Another question is, as far as “cables” between outlets/panel go, is there an advantage of having GFCI protection on top of AFCI protection? If you nail a cable and electrocute yourself, wouldnt AFCI will save you?

 
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02-11-18, 08:22 PM   #21 (permalink)  
I thought combination meant Arc protection plus smaller ground fault detection
laksjdflsak
Combination AFCI devices detect series and parallel faults. The first design of AFCI devices (only breakers) could only detect series faults. They are likely no longer made as they are no longer code compliant. Many AFCI's manufactured use the same, or similar, GFCI technology to detect faults even though they are not listed GFCI protection devices.

In reference to your rant: I troubleshoot many service calls a month where I have to find faults in a wiring system. Knowing how to trouble shoot an issue effectively is something I have learned over the years of being in the trade. Finding a fault is not a daunting as it seems.

More people a killed by electrical fires than that by electrocution in the home. The primary reason for the NEC (which is put out by the NFPA) is fire prevention with electrical safety is a close 2nd. The areas where electrocution hazards are in issue is where you will find GFCI protection. AFCI is another layer of fire protection on top of the over-current protection of a fuse or circuit breaker.


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02-12-18, 06:24 AM   #22 (permalink)  
IT's the GFI that offers shock protection. . AFI is targeting causes of fires. I don't know all the algorithms that the various manufacturers use. I will say I have powered up a 60 Watt light bulb, Line to earth, fed from a GE AFCI breaker. So, that's a 500 mA ground current it had no issue with.

 
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02-12-18, 06:27 AM   #23 (permalink)  
Posted By: telecom guy IT's the GFI that offers shock protection. . AFI is targeting causes of fires. I don't know all the algorithms that the various manufacturers use. I will say I have powered up a 60 Watt light bulb, Line to earth, fed from a GE AFCI breaker. So, that's a 500 mA ground current it had no issue with.
When you say it had no issues with, it didn't trip?

Can there ever be a case where having only AFCI protection would be insufficient for cable related accidents: i.e. someone cutting open a romex cable by accident, drilling through one, nailing one, or grabbing bareconductor (damaged insulation)?

I'm just asking these questions because it's not clear to me if having a GFCI "breaker" has any advantage whatsoever OVER an AFCI breaker for the "cable portion" of a circuit. It sounds like AFCI is what you really need for cable related accidents and GFCI is for outlets because thats where 5mA level high sensitivity electrocution can take place?

 
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02-12-18, 08:00 AM   #24 (permalink)  
Again; the arc fault saves the structure from fire, due to its ability to detect arcing. GFI is a fast attack switchoff if it sees ground current. Most likely due to a human in the wrong place as a conductor.
You can have a fire producing arc with zero ground current. So, the GFI doesn't take care of that case.
Of course, you can also have a shock with no ground current as well, and to date, there is NO breaker for that one.

 
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02-12-18, 09:14 AM   #25 (permalink)  
Posted By: telecom guy Again; the arc fault saves the structure from fire, due to its ability to detect arcing. GFI is a fast attack switchoff if it sees ground current. Most likely due to a human in the wrong place as a conductor.
You can have a fire producing arc with zero ground current. So, the GFI doesn't take care of that case.
Of course, you can also have a shock with no ground current as well, and to date, there is NO breaker for that one.
Well, I got one AFCI/GFCI today from a local supplier just to try it out. If I press the "test" button of the outlets, the outlets trip before the breaker (good). But if I use a GFCI tester and press the test button the breaker trips before anything else in my circuit like you guys predicted (bad). I'm not sure what that is saying and what would happen in real life tripping.

So now I have to make a decision:

1- Leave everything as is, standard breaker paired with every outlet in GFCI in parallel
2- Install CAFCI breaker only (I'm assuming this is not going to trip before GFCIs when there is a ground fault). I have one coming in mail today, I will verify.
3- Keep the CAFCI/GFCI in place.

I dont know if the "GFCI" part of AFCI/GFCI breaker adds any value in a circuit when every single outlet has its independent GFCI outlet.

What would you do?

 
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02-12-18, 09:20 AM   #26 (permalink)  
Additional GFCI devices do not really provide any additional protection. There is always a hypothetical situation you could come up with one way or the other, but you're looking at well below 1% difference in risk profiles. My opinion -- not worth worrying about.


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02-12-18, 09:24 AM   #27 (permalink)  
Posted By: ibpooks Additional GFCI devices do not really provide any additional protection. There is always a hypothetical situation you could come up with one way or the other, but you're looking at well below 1% difference in risk profiles. My opinion -- not worth worrying about.
But what do you mean, which option do I go with?

My main concern is tens of feet of romex in my basement/garage ceiling that is exposed PLUS the area where my breaker box is literally like a "spider web". Its very disorganized, a lot of broken/cut staples that are next to cables, cables wrapped around HVAC duct work sharp edges, etc. I cant fix all of those things because its the entire house. I am just trying to find the best balance between "convenience/comfort and safety".

 
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02-12-18, 04:26 PM   #28 (permalink)  
Bump, can you please let me know what you would do?

 
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02-12-18, 04:53 PM   #29 (permalink)  
I would test the incoming breaker before I would know what to do. If the AFI was not sensitive to ground faults, I would prolly use it.

 
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02-12-18, 05:05 PM   #30 (permalink)  
Cool will do.

on this topic, these new breakers have a strange square screw on them. Got a klein tools specific screw driver for this and I m guessing its used only for this purpose.

how tight do you guys make these? Hand tight is good enough? I m guessing if you really go at it, you can crack the plastic. I have a lot of sensitive torque wrenches at home but I never owned/used a torque “screw driver” so its uncharted territory for me i m hoping hand tight is good enough.

 
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02-12-18, 05:11 PM   #31 (permalink)  
I don't know the torque spec off hand, but it is speced by the manuf. Wiha even makes torque screw drivers insulated to 1kV, if the need should arise.

https://www.amazon.com/Wiha-Insulate...ue+screwdriver

and, if you can turn off the power first:

https://www.amazon.com/WIHA-28595-53...wdriver+square

 
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02-12-18, 05:25 PM   #32 (permalink)  
Well those are nice and I am all for high quality tools so dont get me wrong but cant justify $200 for something I am only going to use literally 10 times now and probably once every decade going forward i ll go with hand tight for now

 
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02-12-18, 06:09 PM   #33 (permalink)  
I dont know if the "GFCI" part of AFCI/GFCI breaker adds any value in a circuit when every single outlet has its independent GFCI outlet.

What would you do?
I would install a AFCI breaker and GFCI receptacles where required.


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02-13-18, 10:24 AM   #34 (permalink)  
But what do you mean, which option do I go with?
Same as Tolyn recommends. Code does not require GFCI protection on the cables, only at the receptacles.


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02-13-18, 01:51 PM   #35 (permalink)  
Posted By: ibpooks Same as Tolyn recommends. Code does not require GFCI protection on the cables, only at the receptacles.
Well good news, AFCI breaker + GFCI outlets work beautifully. I installed 8 breakers so far, all good.

One issue I had, which was strange was, of one of the circuits, I finished installing the breaker, turned it on and went to a GFCI outlet to insert my GFCI tester. As soon as I did, an extremely loud buzzing noise came out and the outlet fried itself - very very bad smell I must add, my god it smells like dead animal. I opened it up and there was no visible short/burned wires.

My iphone charger USB cable was plugged in to that outlet (no phone plugged in though). And I inserted the GFCI tester to the adjacent/load non GFCI outlet next to it without unplugging the USB charger. I'm wondering if the UsB charger somehow caused a dead short there? I dont know.

I changed the outlet now and everything works, I'm pretty sure the outlet box was fine because I have been using that for weeks now.

 
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02-13-18, 03:24 PM   #36 (permalink)  
My bet is on a faulty receptacle with some sort of manufacturing defect.


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