GFCI Downstream Protection

1979-built house, two bathrooms sharing a common wall, one plain electrical outlet in each bathroom. Both outlets are on the same circuit; i.e., one circuit breaker kills them both.
I want to install GFCI protection. Do I need to install one in each bathroom?
Or is the downstream one protected by its upstream brother? If yes, how do I determine which one is first in the circuit?
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On 03/10/2016 08:40 AM, Wade Garrett wrote:

GFCI outlets have "downstream" terminals. if you use them, the outlet connected to it is protected as well.
Full instructions should be included in the box, when you make your purchase
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Are things different in the US? In the UK, our protection is in the consumer unit / fusebox / whatever it's called over there. Replace the breaker with a GFCI one, and both are obviously protected, as you've proved that that breaker kills them both.
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On Thursday, March 10, 2016 at 9:40:36 AM UTC-5, Wade Garrett wrote:


If you look at a GFCI receptacle, you will see 2 set of terminals: Line and Load. The source wires need to be attached the Line terminals.
Any downstream receptacles that are attached to the Load terminals will be protected by the GFCI. Receptacles connected to the Load terminals should not be GFCI receptacles - they don't need to be because they are protected by the upstream GFCI.
If you attach a downstream receptacle to the Line terminals, it will not be protected by the GFCI. In that case, you could use a GFCI downstream, at the extra cost but possibly greater convenience in case it trips. (Local reset)
Another option is to use a GFCI breaker and protect all fixtures on that circuit.
BTW...I know you didn't ask, but a GFCI receptacle or breaker can be used to allow you to use 3-pronged receptacles on circuits without a ground. Yes, it's code! The receptacles should be marked with a sticker that says "No Equipment Ground" so that users are aware of that fact. Using a GFCI as the first receptacle on a circuit (or a GFCI breaker) adds both safety and convenience for receptacles without a ground.
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On Thursday, March 10, 2016 at 9:40:36 AM UTC-5, Wade Garrett wrote:


its best to install a GFCI outlet at each location.
if just one feeds both bathrooms, in a failure mode your stuck.
no hair dryer for you
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I agree. My downstairs GFCI feeds the upstairs bathroom.
To determine which feeds the other, look to see which outlet has two pairs of wires. One comes from the breaker, the other goes to the second outlet. Then you need to determine which pair comes from the breaker, so you don't connect the GFCI backwards.
But what if both outlets have two sets of wires? In that case you have additional outlets, and would have to disconnect one and see if the other is dead when the breaker is restored.
Fred
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wrote:

A GFCI has 5 connections, ground, line in, line out, neutral in, and neutral out.
To find which one is first in line check to see which one has more wires in the box. The one that feeds through WILL have 2 cables entering the box. The second one may or may not. If both have wires in and out, disconnect the wires in one box and see if the other is still "live". If so, repeat at the other box.
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Hi Wade,
On 3/10/2016 7:40 AM, Wade Garrett wrote:

No.

You can wire a GFCI so that *other* loads "beyond it" are protected by the same mechanism in THAT outlet. There are two terminals to which you wire the "line" coming to the GFCI. Two other terminals allow you to wire a "load" (i.e., the other "downstream" outlets) that acts AS IF it was plugged into this receptacle.
I'm not fond of using GFCI's in this way. Instead, I opt to replace the circuit breaker feeding that circuit with a GFCI breaker. They seem to be more durable (I hear of friends/neighbors replacing GFCI outlets pretty regularly; we've not had to replace any of the *5* GFCI breakers here in over 20 years).
[Remember, if the GFCI *breaks*, you lose both bathrooms until you get it replaced]
Some folks will put multiple GFCI's on the same branch circuit (in your case, one in each bathroom; wiring the downstream outlet to the *line* terminals of the first GFCI -- think: pigtails). I've heard complaints that the GFCI's wired thusly interfere with each other but don't know if that is just a symptom of some OTHER problem.
To determine which receptacle is upstream vs. downstream, turn off power to that branch circuit. Verify it at *each* receptacle (unless you are 100% positive that they are, in fact, on the same circuit). Then, look at the number of black wires "terminating" in each box (or, white if that's easier for you).
For the upstream device, there should be exactly two blacks -- one bringing power from the panel and one delivering power to the downstream device. For the downstream device, there should be exactly one black -- from the upstream device!
If you see anything other than this, then there are other devices on the circuit (or, it is actually two circuits!).
The trick now becomes sorting out which of the two black wires (AND THE ASSOCIATED WHITE) in the upstream box are providing power from the panel (and which are supplying power to the downstream device).
With the breaker still off, short the black and white wires in the downstream box. Then, using a voltmeter (or, a flashlight hacked as a crude "continuity tester"), check each white to it's corresponding black (you should be able to see which white mates with which black by looking carefully). The white-black pair that appears as a short is the pair that feeds the downstream box.
[Verify this by unshorting the downstream wires and noting that the "short" no longer appears at the upstreeam box]
[[It is *really* important to get the whites paired correctly!]]
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On Thursday, March 10, 2016 at 2:33:15 PM UTC-5, Don Y wrote:

And then when it trips, instead of resetting it where you are, it's a trip to the panel to figure out which one it is.
They seem to be

OMG, perish the thought. Per his statement, it's just two receptacles.

Wrong. You could supply power from that circuit to other loads too.

Wrong again, because it could feed other loads too.

Well, duh!

Strange way of figuring out the obvious. You can just separate the wires, turn the power back on and see which is hot.
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On Thursday, March 10, 2016 at 9:40:36 AM UTC-5, Wade Garrett wrote:


Outlets connected to the downstream side are protected by the one GFCI. To figure it out, if you can get an idea of how the wiring was probably run, that's a start. If you can't see how it might be run, I'd just start with the one closest to the panel. Pull it out of the wall. If it's feeding to elsewhere, separate it, turn the power back on, see which half is live, which dead and proceed from there.
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On 3/10/16 9:40 AM, Wade Garrett wrote:

Thanks for the info. I guess my first step is to take a look inside the boxes and see what's there.
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