what is up with my outlet?

in my bathroom, and only in my bathroom, the outlet has two little buttons that say “test” and “reset”. i can not for the life of me figure out what that means… ive tried pressing them but nothing happens. any advice?

Its a Ground Fault Outlet used in bathrooms and kitchens when moisture is present. Read more about it here.

If you hit the “test” button and the outlet is still powered, you need to get a new GFCI outlet installed. If pressing the test button turns the power off to that outlet, you’re good to go.

GFCI monitors if there is more current flowing “out” of the hot side than is flowing back “in” the neutral side. If there is, then that means current is either flowing down the ground wire, or down you and the power needs to be shut off immediately. These are used in bathrooms and kitchens, or where there is lots of water to prevent electrocution.

Toddly & Cheesesteak filled in a lot of the “how,” and now I’m going to attempt to polish up the “why.”

Circuit breakers protect the wiring from fire, if everything works. If there’s more juice than you’re supposed to have, the breaker will shut off, after a few :eek: seconds. If some of the juice is going to ground (through you,) a breaker will often not shut off. You are not a very good conductor, so you could get enough to kill you and still not blow the breaker.

Ground Fault Interrupt Circuits work differently. They measure the electricity flow from hot to ground (there should be zero flow.) If there is any, the GFI will snap off immediately. If there’s a little short in your hair dryer or shaver, and you grab the faucet, the GFI will save your life.

They’re mandatory in the bathroom, but other uses are a good idea. For example, if you have a water bed, put one there. If you work on dripping wet cars in the garage, your outlets should be GFIs. Any kitchen outlets? Those, too.

Good suggestions AskNott, all “outside” outlets should be GFI. However your suggestion about GFI’s in kitchens does not apply in Canada.

Canadian electrical code states that each duplex receptical above the counter has to have 2 seperate circuits going to it (top plug has one circuit, the bottom has a different circuit). This is done by removing the little metal tab between the screws of the outlet.


Not quite. GFCIs work by monitoring the current differential between the hot leg and the neutral leg, as Cheesesteak said. The do this by passing both the hot and neutral through a single turn of a differential current transformer. The secondary of the CT has something on the order of 1000 turns, and will produce a voltage across the secondary which is proportional to the current differential times the turns ratio. Now, when the current flow through the hot leg exactly equals the current flow through the neutral–as is the case in a normally-operating circuit–the two opposing currents cancel or “buck” out resulting in zero voltage across the CT secondary. However, if some of the current is diverted to ground through another path, then the difference in currents induce a proportional voltage across the secondary. If the current differential exceeds, typically, 5 mA then the GFCI trips and cuts off the power to the circuit.

:confused: What’s the reasoning behind having to have two separate circuits? It better be a good one if it’s preventing you from using GFIs in the kitchen.

Actually, in the U.S. they’re mandatory in the bathroom, kitchen, outdoors (which also require a water-resistant cover), garages (accessible, non-dedicated outlets only), hydro-massage tubs, unfinished basements, and sometimes laundry rooms.

It’s not a sugestion, it’s required by law by the NEC. As the CEC is based closely on the NEC, I’m very surprised that it’s not the requitement in Canada as well as the US. Are you sure it’s not? I fail to see how separating the circuits provides any safety whatsoever. I’d appreciate it if you can point me to the relevant portion of the CEC.

I can’t find the CEC cite, but this keeps popping up on the search engine. They feed the outlets with two circuits and cut the strap, using a common neutral. Makes no sense to me…

The only explanation for the “split duplex” that I can think of is that it might balance the load better, because each half is from 1/2 of the 220 volt circuit. I guess it’s possible that if you provide all the 20 Amp circuits in the kitchen from the same side of the breaker box and then plug in a bunch of waffle irons at the same time, bad things might happen.

According to that link, the CEC does require GFCI, although the site is mum on whether GFCIs still work if you split the duplex.

I’ve never seen a GFO in any of those places. Should I get some installed, or is there some other safety mechanism in place I’m unaware of?

Me either. But, this is Canada, after all. Maybe Red Green wrote the CEC. :wink:

The outlets themselves do not have to be dedicated GFCI fixtures. They may be connected to a master GFCI on the circuit someplace, usually a GFCI outlet someplace in the room, but ocassionally in another room, but on the same branch circuit. If not, chances are the building was constructed prior to GFCIs being required (~1986, IIRC?), If this is the case, you can replace existing outlets with GFCI outlets fairly easily–they are drop-in replacements for fixtures in standard electrical boxes. They go for about $10 each or so.

Are split outlets allowed to be wired on separate legs? If so, such an outlet will have 240 VAC between the upper and lower receptacles. If handheld appliances are plugged into each outlet, and something really “bad” happens where someone receives a jolt, the current will be 2X through the body vs. a 120 VAC jolt…

Sorry: The NEC is generally for new construction or renovation. If you bought your house and the outlets weren’t there, you’re okay, although many city codes will require you to upgrade them prior to selling. It’s a good idea to do it even if not required. Water and electricity just don’t mix well.

CrafterMan: Reading the cite I provided, it would appear that the outlets are all fed with two circuits, i.e., 220v. I don’t know why they don’t just feed every other outlet with a separate circuit rather than go to the trouble of butchering the duplex.