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Low voltage

I have 2 outlets and 1 switch showing low voltage-107. The other outlets on the same breaker are okay.

Reply to
Dennis
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How do you define "OK"?

What other *active* loads do you have on the branch circuit? (as you probably don't know how the wire was actually *run* between the various fixtures).

Turn off *everything* on the branch circuit and measure again.

Reply to
Don Y

How are you checking the voltage? Hot to neutral? Hot to ground? Is there voltage between the neutral and ground?

Reply to
Dean Hoffman

Is it Al wiring?

Reply to
Tony Hwang

Ok- the voltage is 118 No active loads on circuit.

Reply to
Dennis

118 iis normal probably variations of tolerances of your meter
Reply to
bob haller

You have a bad connection, probably at a device in the last box that works right or the first one that doesn't. If you have an IR (non contact) thermometer, I bet that one will be a little warmer when the circuit is loaded.

Reply to
gfretwell

Are you *sure*? What do you *think* is the extent of the circuit? I.e., if you think it is just a switch and two outlets, chances are you've missed something. What do "all" of the other (known) points in the circuit indicate?

When you turn on the switch, does come on?

When you plug something into the outlet(s), does it "work"?

That doesn't sound likely. You only get an IR drop if current is flowing. I'm pretty sure (sight unseen) that his DVM/VOM/whatever is extremely high impedance. To drop *11* volts (the "bad" voltage in the OP) he'd need such a high resistance connection that *nothing* plugged into the affected outlets would work!

Play with numbers:

- if his DVM drew a whopping 1mA, he'd need an 11K ohm "connection" for 11V to develop across it with just the meter as a "load". So, into a DEAD SHORT, the 118V "supply" would only provide ~10mA! An incandescent night light (4W) draws more than 4 times that!

- if his DVM has any silicon in it :> it's input impedance is more like 10Mohms. So, the "load" it presents is more like ~10uA. I.e., to drop 11V in that "bad connection" you'd need an effective resistance of close to 1Mohm. Again, a dead short would limit a "legitimate" load plugged into the outlet to 13mW: which might keep a *fly* warm on a cold night...

I suspect there is "something" that is actually drawing power on that leg (including upstream) of the branch circuit: overhead lights, a forgotten outlet, etc. Even then, dropping 11V *anywhere* on a branch circuit suggests something screwwy.

(How long of a run is this?)

Reply to
Don Y

In case these "dead short" numbers are confusing, think of them as the maximum power that could be delivered from the circuit through each of these "connection resistances". I.e., if you can light anything bigger than a 4W night light (fully) from that outlet, then the connection resistance must be less than the figure I've stated (11K, 1M, etc).

Reply to
Don Y
[snip]

I remember finding something unexpected when I checked the circuits in this house. The receptacle behind the refrigerator appeared to be the only thing on that circuit. However, when I was checking the breakers, I found the bathroom light was on it too.

BTW, the way this house is arranged that bathroom is between breaker panel and kitchen.

[snip]
Reply to
Mark Lloyd

Be thankful that's *all* you found! In our case, the two bathrooms, garage and outdoor outlets were all on the same branch circuit. (because all of those need to be on a GFCI and, at the time, could apparently *share* a GFCI circuit instead of requiring individual circuits).

So, if you happened to have two hairdryers running at the same time (two people getting ready for an outing at the same time), you'd trip the breaker. Or, if the freezer out in the garage decided to turn on its compressor while you were drying your hair, etc.

In your case, there is relatively little chance that the bathroom

*light* (assuming it doesn't have a "convenience outlet" attached) will pop the breaker and leave your refrigerator without power (food spoilage). Ideally, a refrigerator should have its own branch circuit so *it* is the only thing that can "pop its breaker".

So, while your refrigerator is "running", you should see a slightly lower voltage across the light in the bathroom. The difference will depend on the length of the wire run TO THE KITCHEN (the bathroom has no impact on the measurement cuz the meter draws no power while you are measuring!), the size of the wire (#12AWG vs. #14AWG -- lower numbers have less resistance per linear foot so less "drop"/loss in the wire itself) and the amount of current flowing through the wire TO THE KITCHEN (when *no* current is flowing, there won't be any losses ANYWHERE in the circuit). The voltage that you see AT THE KITCHEN will be even lower because the extra wire length between there and the bathroom will represent more "loss".

I babysat a friend's house many years ago and was strongly admonished not to use the outlet behind the refrigerator: "It blew up Tracy's microwave oven!" (Yeah, sure... :> ). Curious, I took out my multimeter and checked the voltage across the outlet: 240V! "WTF???". Turns out, electrician had miswired the outlet when it was installed (some homes run "two circuits" in a single cable to save wire: the two "hots" and one neutral that feed your home. Think of it as +120 and -120). In this case, instead of picking ONE of the hots (doesn't matter which one) and THE neutral, he picked the two hots.

Ooops!

Reply to
Don Y

That's scary. How do you fix a mistake like that?

Reply to
Muggles

You hope the neutral is in the box, and swap it for one of the hots. Otherwise time to rewire the circuit.

Reply to
FrozenNorth

Instead of using #12/2 w/ gnd to wire *individual* circuits (the "gnd" being the "safety ground" that you see as the third hole on an outlet and the "/2" being the two conductors -- hot + neutral), the trick that is used (to save wire and labor) is to use #12/3 w/gnd -- the extra "third" conductor is "the other hot" (the neutral and gnd are *shared*).

You run this cable from outlet to outlet and either connect hot #1 or hot #2 to the actual outlet (gnd and neutral are always connected). So, you can do things like every "odd" outlet is on the same circuit and every "even" outlet is on the OTHER circuit. Perfect for kitchens!

This saves wire overall. Instead of running 50 feet of hot #1, neutral and ground for one circuit and then ANOTHER 50 feet of hot #2, neutral and ground for a second circuit (3 * 50' + 3 * 50' = 300), you run 50 feet of hot #1, hot #2, neutral and ground (4 * 50' = 200). Less wire, less labor.

So, inside EVERY junction box you have these 4 wires. Just pick the

*right* group of three (one hot, THE neutral and THE ground -- instead of TWO hots and THE ground).
Reply to
Don Y

On 11/18/2015 1:34 PM, Muggles wrote: ...

Look up "Edison circuit" and you'll see how it was wired. As noted, it's a simple mistake of picking up wrong conductors for the one outlet; the neutral's got to be there or the other wouldn't function correctly, either.

Reply to
dpb

I don't understand everything you said about the different wires, but I get the general idea of what you're saying by your last paragraph. I've seen a few instances of different people wiring up lights and ceiling fans and have seen those 3 wires, so it makes more sense with your explanation. thanks!

Reply to
Muggles

Real easy if the neutral is in the box. Remve 1 line wire from the outlet and replace with neutral. Or install a "split" receptacle

Reply to
clare

Seen that done, idiot didn't split the receptacle, and kept wondering why the breaker would toss. That pesky little tab that should be removed. The guy was a mechanic, obviously his electrical knowledge summed to about zero.

Reply to
FrozenNorth

Pretend you're a mailman/delivery man.

Every house gets a phone bill and an electric bill. These are the equivalent of the neutral and ground wires.

Half of the houses have natural gas heat and the other half burn oil. So, some houses get heating oil bills and some get natural gas bills.

You could start out in the morning with the phone, electric and natural gas bills... and, deliver those to every house that gets THOSE three bills. You will drive past some houses because they don't have natural gas!

Then, make a second trip in the afternoon with the phone, electric and OIL bills... and, deliver those to every house that gets THOSE three bills. These will be the same houses that you "drove past" in the morning. And, you will now end up driving past the houses that you delivered to in the morning!

You've expended a lot more effort (wire) to reach those same houses and deliver the same number of pieces of mail, *TOTAL*.

If, instead, you carry *all* of the mail with you and SELECTIVELY give phone + electric + {gas or oil} to each specific house, you've driven less overall.

Reply to
Don Y

Which way is easier to do? The split receptacle, I'm guessing?

Reply to
Muggles

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