Howdy all,
My wife and I are in the process of remodelling our 20-year old kitchen. At the moment none of the outlets in the kitchen have GFCI protection, and we’d like to fix it.
I’d hoped it would be as simple as replacing the breaker at the panel with a GFCI breaker, but I’ve run into a bit of a snag that I hope the electrical experts can help me with.
The feed from the panel to the first receptical in the series is actually 12/3, not 12/2, with the red and black wire connected to separate breakers to power two separate circuits. When the 12/3 arrives at the first receptical, the black wire is used to feed the counter recepticals, and the red wire goes off to power the trash compactor. Both circuits share the same neutral (everything is pigtailed in one massive bunch in the first box).
What is the right way to get GFCI protection to the recepticals?
Thanks!
Neil
Replies
please expect a lot of comments about code and kitchens in general. To bring a kitchen upto code requires 5 or 6 circuits, some 20amps
a GFCI recepticle will also protect the recepticles downstream from it.
bobl Volo, non valeo
Baloney detecter
Yes, I'm afraid I'll get a lot of those as well. There is more than one 20 amp circuit serving the outlets in the kitchen (there are three). Two of the three have this problem :)
Neil
You can't use a regular 120V GFCI breaker to feed part of a circuit with a shared neutral. (Well, I suppose you can, but it won't work.)
Choices:
-- Use a 240V GFCI breaker to feed both legs of the circuit.
-- Rewire so that there are separate neutrals feeding the two halves of the existing circuit.
-- Install a GFCI outlet in the first outlet position of the circuit, then use the feed-through from that outlet to feed the others (taking care to assure that they aren't using a shared neutral somehow).
If there's space in the box where the multi-wire circuit splits into two branches, put a GFI receptacle in there, and connect the wires feeding the next receptacle in line to the terminals on the GFI marked "LOAD". This will provide GFI protection to those downstream receptacles as well.
Multi-wire circuits are not weird, once you know what there about. They save resources (one less copper wire 'cuz of the shared neutral), they make for better electrical efficiency (less voltage drop), and provide savings in installation labor (one cable instead of two to run and staple). One thing about multi-wires circuits, just be sure that the splice for the shared neutral where it splits into two circuits is very secure. Pretwist the wires, trim, and then wire-nut with a high quality wirenut.
I bring up the space (volume) issue because often electrical boxes on the small side are used to save a few pennies, and so there's not enough space to put a GFI receptacle in. Be advised that wires need a certain amount of space in the box to dissipate the heat that develops from normal power flow through the wires. The Fine Homebuilding website has an article on "box fill", i.e., how many wires and such can safely inhabit a box of a given volume. So it's really not an issue of whether you can physically cram the wires, splices, and GFI receptacle in there.
If the box is too small, there's a fix that's usually easy. The box can be removed, and a new box--one with more volume--installed. Because you're remodeling, you ought to be in a good position to upgrade the box(es) if need be.
If the refrigerator receptacle is on the circuit, it'll become GFI-protected. There's nothing inherently wrong with this, it's just that many appliances will develop leakage to ground as thewiring ages, and collects dust. Without a GFI, as long as the equipment grounding conductor (ground wire) is good, any slight leakage current will flow on it and present no hazard. But, if the outlet is GFI-protected, it's a bummer if the fridge trips the GFI and you don't notice it for a while--like if you're away for a weekend.
Once a leakage path develops, it usually just gets worse. I had a situation where a 15 year old fridge tripped a GFI on occasion, and we figured out that it was when the kitchen floor was mopped--the floor-level dampness, combined with the old wiring and inevitable dust, caused enough leakage current to trip the GFI.
For the same reason--nuisance tripping--I'd recommend against using a two-pole GFCI circuit breaker if the refrig is on the circuit you need to GFI-protect. Besides, GFI-protecting the garbage disposal is unnecessary and it'll more than double the chance that the GFI circuit will nuisance trip. Given that garberators mix power and water, there's even more chance of harmless current leakage. Most two-pole GFI breakers are common-trip, i.e., if one side trips, it shuts off the other side too. So a little leakage on the garberator side trips the receptacle circuit side, and again, no power to the fridge (if it's on that circuit). There are 20A, independent-trip, two pole GFCI breakers available for some panels, but they're usually special order and are even more expensive than an common trip unit.
Yea, O.K., I'll say it--a remodel is a great time to upgrade the wiring in a kitchen. You can never have too many circuits in the kitchen...kitchens are the one part of the home where the trend is more appliances that use more power. I just finished a kitchen remodel for a client and installed a subpanel and 14 circuits (2 for lighting, 4 small appliance [countertop receptacles], garberator, trash compactor, microwave, refrig, range hood, convection oven, expresso machine, and dishwasher. This was not a huge kitchen, either. So if you have the walls open, run some more circuits if there's any chance that you'll need 'em.
Cliff
Edited 7/10/2006 12:55 pm ET by CAP
Cliff,
Thanks for your detailed response. Just so I'm clear on the connections for the common neutral, are you saying I do the following:
1) Take the incoming neutral and pigtail it into two ends so it has one lead going into the LINE side of the GFCI, and the other to the neutral connection of the disposer circuit.
2) Connect the outgoing neutral for the receptical circuits and connect it to the LOAD side of the GFCI.
As for the fridge, that one was easy. It's on its own circuit with two additional recepticals downstream. I added a GFCI to the second receptical.
Thanks for the note about box fill. I did run into that problem after doing calcuations for an additional wall switch, and had to upgrade to a bigger box. Patching the drywall was the worst part!
At the moment there are no plans to open any of the walls during the remodel. I've added a new circuit through the crawl space for undercabinet lights, and I believe aside from the GFCI issue everything else is decent: separate circuit for dishwasher, disposer, ceiling lights, stove, plus two circuits for the countertop (three if you count the icky shared one with the fridge). The compactor is also on a circuit and will be removed as part of the remodel giving me a free circuit if I need it for something.
By the way, you must be from Canada. I haven't heard "garberator" in years :)
Neil
You have the wiring correct.You don't need to do DW patching to install a larger box.You can use a single ended hacksaw or a metal cutting blade in a sawzall.Then pry on the box enough to get a gap between the box and stud and cut the nails holding it in place.Then pull out the old box (or drop in in the wall.Then install an Old Work box.
Neil,
You're welcome! Not Canadian, but spend time in Alta/B.C every year and so pick up the lingo and pretty much the accent, eh?
Looks like you're in great shape on the wiring. And I like your choice to deep six the trash compactor--I can't see the value in an appliance that turns five pounds of trash into five pounds of trash...and anyway, more frequent trips to the trash can are good exercise.
On the neutral splice, you've basically got the idea. The neutral of the multiwire cable gets spliced to two wires: 1) a pigtail that goes to the line side of the GFI recep, and 2) the the neutral of the cable going off to the garberator. I wouldn't use a pigtail to connect to the garb. circuit neutral. It'd just be another splice to possibly fail and another wirenut takin' up space in the box.
What you never want to do in this situation is use the "line" terminals of the receptacle to make that neutral splice where the multiwire diverges. If that connection fails, you get a 240V circuit across the two loads in series. And the voltage will divide across the loads inversely proportional to their resistance. So, for instance, if you have a toaster and a radio plugged into the two parts of the multiwire and lose the neutral, the toaster will see maybe 80 volts and the radio 160. That ain't good for the Bose Wave!
If this happens at the service to your house (which is just a big multiwire circuit providing 240/120V to the whole house via the breaker panel), the voltage imbalance can blow the brains of electronic devices, or cause enough heating at marginal splices to start fires. That's why most light and power companies come a-runnin' to check their connections at the transformer and drop, if you report lights flickering with some getting brighter coinciding with others getting dimmer.
Good luck on the project,
Cliff
Edited 7/10/2006 2:11 pm ET by CAP
That's why most light and power companies come a-runnin' to check their connections at the transformer and drop, if you report lights flickering with some getting brighter coinciding with others getting dimmer
Dunno, the protection kicked out with a bang before they got to my house one Sunday night about 2200. Service tech re-enrgized at the circuit protection, and was surprised when I came back to tell him I was only half-electrifed (he clean missed my report of half too-bright, half too-dim. He pops my meter of an got 0 on one leg. We go next door (my 12v lantern is much better than his dead flashlight, it seems), he pops that meter--it has a dead leg too. One more house up the street, and he decides it's a pattern, all right. Then, and only them, does he call the supervisor to go wake up a pole crew to go get a new can. Except the new guys repeat all the checks when they drag out. That was a long morning, wasn't until 0340 that power was restored. Made for a peachy monday at work, too.Occupational hazard of my occupation not being around (sorry Bubba)
I'd recommend GFCI receptacles over GFCI breakers in general. And further that they only feed downstream receptacles in the same room. That way when they trip, you know you only have to push the button on the one in the room with you, not schlep all the way back to the panel.
-- J.S.