GFCI?

gqjeff

LifeTime Supporter
Jul 19, 2010
203
IL
Just curious who uses them in the box and who uses recepticles? Does anybody use both for added protection or overkill?
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,471
SW Indiana
Doubling up really doesn't add much. I use a GFCI breaker for my 220 and outlets for the 110.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
There are pros and cons.
Generally speaking, GFCI receptacles are cheaper than breakers, but only it and the devices downstream from it are protected. The wiring between it and the breaker are not GF protected. Additionally, upon a trip, one must know where to find the GFCI device to reset it. Sometimes that can involve a trip around the premises to locate the culprit.

GFCI breakers are more pricey, but protect the entire branch, and there is only one place to visit upon any type of trip.

Protection level is the same with either device, so it usually comes down to price, and the circuits are designed to feed a bathroom, kitchen, or garage first, then other wet locations following downstream, and a GFCI receptacle is installed in the first drop.

Wiring in series or 'daisy-chaining' is generally discouraged, though not explicitly forbidden. In this case, one can not be certain which device will trip in any qualifying event. You could press the 'test' button on a GFCI receptacle and have the GFCI breaker feeding it trip. Pain in the butt.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
31,529
Sebring, Florida
ohm_boy.

Your electrical knowledge and experience is really appreciated on the forum.

So, If I were to install say 5 or so outlets in my workshop, would you suggest putting a GFCI outlet at the closest position to the panel or put a more expensive GFCI breaker on the circuit?
 

dremin2flyhi

LifeTime Supporter
Jun 4, 2010
121
Darlington, SC
Dave,
that is standard practice is to place the first receptacle as the GFCI then everything down below is protected. You can get 15A or 20 Amp ones. Normally I only do the GFCI and 3 more rec in the same line.
 

gqjeff

LifeTime Supporter
Jul 19, 2010
203
IL
I used 2 20 amp breakers for my install running 2 receptacles. I just have some extra gfci receptacles is why I was asking.

Thanks
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
Honestly, if I had to buy new, I'd probably get receptacles for the same reason that new construction is done that way - it's cheaper. If I had either one on hand, that's what I'd use, but for 12 bucks / receptacle, and 30 bucks/breaker, I doubt I'd end up with a breaker on hand. That's just me.

So, yes, GFCI on the first outlet, the rest wired from the 'load' side of it.
As for the 15/20 rating on GFCIs, that can be confusing. Let me see if I can floc the water a bit. I mean, clarify...

The circuit capacity is determined primarily by the size of the wire. Max on #14 is going to be 15 amps, #12 max'es at 20*. The breaker is then sized appropriately for that circuit. Downstream devices are also to be sized appropriately.

On a 15 amp circuit, only 15 amp devices should be installed. These are receptacles with parallel blade slots (NEMA 5-15R). On a 20 amp circuit, receptacles with a 'T' slot (NEMA 5-20R) may (would) be used. This allows for 15 or 20 amp appliances on 20 amp circuits, but only 15 amp appliances on 15 amp circuits. So far so good.
Now, we want to consider the GFCI receptacle. There are two distinct aspects of these units: 1) the receptacle, and 2) the GF protection.
1) The Receptacle: They are available as 15 amp receptacles and as 20 amp receptacles, depending upon the rating of the circuit into which it is installed, just like any receptacle. It is, after all, a receptacle, and must function the same and adhere to the same standards as a normal one. NEMA 5-15 and NEMA 5-20, respectively.
2) Protection: As a general rule, the protection circuit of the device is not dependent upon the rating of the circuit into which it is installed. I want to say that again... the protection circuit of the device is not dependent upon the rating of the circuit into which it is installed. This is because they are designed to trip when they detect a current loss of roughly 5 milliamps. That is it's sole protective function. It does not trip on overload, nor on short circuits - that is the breaker's job. Yeah, let me repeat that, too. It does not trip on overload, nor on short circuits. GFCI devices do not provide overload protection, although if it is built into a circuit breaker, the 'breaker' portion does handle that aspect.
It merely compares the current in the hot and the current in the neutral, and if they differ by 5mA, it trips. It does not even need a ground connection to do this, although you always want a continuous ground conductor. Now, having said all that, there is naturally a limit as to what currents the detection components can handle, and that is where the second number of a GFCI's rating comes into play. These are typically built to be able to handle a 20 amp circuit (meaning that it can safely and dependably interrupt a 20 amp circuit), although you may find other values.

So that boils down to either a 15 or 20 amp receptacle, combined with a protection circuit which can handle a 20 amp circuit capacity. A 15/20 rating on a GFCI receptacle indicates a 15 amp receptacle (NEMA 5-15R) and a capacity to provide GF protection for a 20 amp circuit. It does not necessarily mean that you can install 20 amp outlets downstream - remember, that limit is set by the wire size and breaker.

That will conclude today's session on GFCI outlets. Thank you.

*Other factors may limit the capacity of these wire sizes. These are MAX limits.
 

bk406

Well-known member
Dec 3, 2009
2,690
Central Massachusetts
NEC code at this point is GFCI breakers are only required on bedrooms. The reason is actually a reaction to fires that started because of fraid wires in electric blankets and bedroom lamps that started fires. Unlike a GFI outlet, the GFCI breakers are sensitive ANY small short or current leak in a wire. They are much more senstive. As a result, they can be a bigger PITA since any small current leak will trip them. IMO, its a matter of time before the NEC mandates GFCI breakers in the whole panel.

Daisey chaining is accepted practice for protecting multiple outlets (i.e 2 20 amp circuits are required in a kitchen. Normally 2 outlets on each circiut are placed above the backsplash where one plug is the actual GFI and the other is wired in series on the load side of the GFI plug.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
You may be thinking of AFCI protection, or Arc-Fault Circuit Interrupter. It is the job of an AFCI to detect arcing current patterns and open the circuit. While state/local codes differ, the 2008 NEC requires AFCI on all 15 or 20 amp circuits supplying outlets in dwelling unit family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sun rooms, recreation rooms, closets, hallways , or similar rooms or areas.

AFCI is different from GFCI, as the former is designed to actually detect arcing itself, and is meant to prevent fires. The latter is designed to protect people from leakage current, and will typically not stop a fire from starting due to arcing, as long as the current involved does not stray out of the circuit.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
Digressing for a moment re: AFCI... I actually like the idea of AFCI devices. I wish they were more affordable for more refits. Many years ago, I had an arc 'situation' develop in a house I had at the time. The first outlet on a circuit had the screw connector on the hot lead loosen. I don't know if it was never properly torqued or if it loosened due to heat cycling, but it was the circuit into which our vacuum cleaner got connected as it was moved through a couple of rooms, and so it was subjected to 12-14 amp loads. It heated up until it charred the insulation off the wire, and the #12 copper wire eroded away into a couple of points which arced until it finally could not sustain any current flow. The heat melted the composite electrical box in the wall, and stunk like h3ll. That's ultimately how I found it. About 12 feet of romex had to be replaced in the wall, and a junction box was added in the crawl space to splice it. The box and receptacle had to be replaced, and there was consequently sheetrock and paint.
We were fortunate in that all the arcing occurred within the box designed to contain it, but it could easily have been a complete house fire. An AFCI unit would have shut it all down long before any of the wire, box, or receptacle saw any damage. Would have been a PITA to troubleshoot, but it would have been a much safer situation.
 

bk406

Well-known member
Dec 3, 2009
2,690
Central Massachusetts
The biggest complaint I've heard with them is that under certain circumstances, the cycling of appliances can cause them to "think" there's an arc fault when there really isnt one and the breaker will trip. That, and they are really expensive.

Back to GFCI breakers for a second. The only ones I have are in the pool panel where the pump, pool light, and heat pump are tied directly into the panel. The convience outlet is a GFCI outlet with a regular breaker.
 

Ohm_Boy

TFP Expert
May 1, 2007
1,344
Orlando, FL
That's pretty standard. Obviously, a GFCI breaker is better suited for hard-wired appliances such as a pump, light, and heat pump, as it could be cumbersome to wire to a GFCI receptacle. It could also be for 230V, or more than 20 amps, in which case, again, a breaker is the best choice. The outlet is best (meaning most cost-effective) served with a GFCI receptacle.