I just discovered something wrong with my outlets in my home office: if I measure voltage across hot and neutral, it’s the expected 120VAC. However, if I measure from hot to ground, it’s only 60, and likewise it’s 60 from neutral to ground. So if I understand things, either my ground isn’t really ground, or my neutral isn’t really neutral.
Isn’t this totally wrong? How horrible is this? How exactly would you miswire things to end up with this scenario?
You need to trace back through the home office circuit wiring and fix what’s wrong. If you can’t do it, get an electrician.
I have no idea how such a condition could arise, maybe some one on the board can figure it out. It should be corrected.
I think that having different voltages on neutral and ground would interfere with a GFI circuit, so I’d have to say that yes, it’s dangerous. Neutral and ground should be at the same voltage–they’re supposed to be connected at the breaker. If there’s that much potential between them, they obviously aren’t connected.
As to how it could happen, it sounds like what you’d measure if the outlet was hooked to a 60-0-60 transformer (with “ground” on 0). I know next to nothing about how homes are wired, so I have no clue how that’s happening. Q.E.D’s good at stuff like this…
What you need is the 120v equivalent of the 240v megatest 26a. This sucker plugs straight into a power point and it throws out your curcuit breaker in 0.3sec, it tells you what your voltage is, how long it took to trip the breaker and even tests residual current discharge units. use the standards code [as3760] for the google search and you'll get electrical testing equipment.Unplug all the appliances on that circuit, turn off all wall switches and unscrew all the light bulbs and test again. I suspect you’ve got something on there that’s using the ground as the neutral or something of that nature. If the problem has disappeared, you can then start plugging things back in, turning switches back on and screwing bulbs back in one-by-one until the problem reappears. You’ll then have an idea of where to start looking.
Measuring voltage between ground and neutral is meaningless. The hot-to-ground however, should read the same as hot-to-neutral (120v).
So, you have a poor (loose) ground somewhere. (Not the end of the world, but not exactly safe).
Does this apply to the whole office? Open the outlet closest to the panel. Check between the actual ground wire and the hot. If you get a reading of less than 120v, check the ground at the panel (if you’re comfortable in the panel) for a good connection.
If the first outlet reads 120v, work your way upstream to each outlet until you get a “bad” reading. The poor connection is there or in the last good one.
Also look here:
It’s a very informative forum for electrical questions.
To further what QED said, it may well be the outlet that said appliance is plugged into rather than the appliance itself. The 60v from hot to ground perplexes me. Are all the outlets in the run reading this way? Is your wiring romex or in conduit?
On the plus side, light fixtures are seldom on the same run as outlets, so you may not have to your testing in the dark.
As others have said, the 60 volt reading is odd. 120-volt, single-phase (domestic) electricity cannot normally be "broken down: into two 60-volt components. So I’ll ask one of those “smack on the head” questions:
How did you measure the voltage? Did you use a multimeter (reads volts/ohms/amps)? If so, they may have multiple scales, “scale multiplier” switches, and/or multiple test lead sockets. Is it possible you read the wrong scale, had the switches set wrong, or had the leads plugged into the wrong sockets? This could make a 120-volt reading look like 60 volts.
I’m thinking two lighting fixtures or other indentical loads unintentionally wired in series. The connection between them would present 60 V wrt ground, since we’d essentially have a voltage divider. Thre’s probably other possibilities, too, but this cold/flu medication has my head all fuzzed up.
If you have 3 prong Std. NEMA outlets you can get a tester for same at the big box home stores for a few bucks. It will tell you if something is amisss.
Your neutral is obviously not at ground as it should be and may be at a ‘floating’ potential.
No, guys the 60 v between neutral and ground is irrelevant, and not odd at all. Remember, both of these wires theoretically go to the same bar in the panel. There are inductive voltages which can set off these kind of readings.
The problem is in a partial ground.
No, I don’t think so. A high-resistance path to ground should still read as approximately zero volts, unless there is current in the ground wire, which is a bad thing. The ground should not carry any current at all under normal conditions.
Right. Wouldn’t it make sense to turn off breakers one by one and determine which circuit is providing the voltage to the ground (and thus is the circuit with the problem)? Once you do that, you could unplug all the appliances on that circuit and then turn the breaker back on to see if the voltage is still there. If it is, then there is a problem in the house wiring. If there isn’t, one of those appliances is faulty. Does that make any sense?
You do not have a good ground connection at some point in this circuit.
Start at the panel or wherever the source of power to the office comes from. Then go to the first outlet and work upstream from there.
This is phantom voltage caused by inductance. A high-quality tester won’t show this voltage.
Read this
Electrician here.
What caused you to test this circuit? Were you having problems that you haven’t mentioned? And, is the rest of the house the same?
Could be your meter. Could be an open nuetral or an open ground.
The circuit appears to work correctly from what I’ve read so I’ll assume for now that it is an open ground.
Let’s check something though. Find the breaker and turn it off (plug a radio in and turn up the volume so you can hear it at the breaker location- when the radio goes off you’ve found the breaker). Check for voltage between the hot and the nuetral. The hot should be the shorter slot and the nuetral should be the longer slot (on the left as you look at the outlet).
Neutrals will sometimes have the T shaped slot also (on 20 amp plugs).
After testing for power, unplug everything on that circuit. Unscrew any light bulbs that you think are on the circuit as well. At the very least make sure the light switches, dimmers and fans are all turned off.
Now, go back to one of the outlets in question and double check to make sure the power is off. Then switch your meter to read OHMs and take resistance readings between all the prongs on the plug. Hot to nuetral, hot to ground and nuetral to ground. This will narrow down the problem.
Come back here with the results.
You should read an open circuit between the hot and the nuetral, and also between the hot and the ground. You should detect a direct short between the nuetral and the ground.
That’s right. I have been using a Fluke for the last 5 years. Before that, I would occasionally get phantom readings. Voltage “Proximity” testers, or, as we call them in the field-“Death Sticks”, are good for picking up phantom voltages and therefore are not very reliable.
Are you measuring with a digital meter or a “wiggy”?
The high input imedance (typically 10, 11 or 22 meg) will pick up all sorts of phantom volts out of the air. A wiggy has a much lower impedance and isn’t affected by phantom or stray voltage or mis-read scale multipliers - it’s got one scale - zero to 600 volts.
Good news is a wiggy should only set you back $25 or so.
When all’s said and done, I’m betting on a bad ground connection somewhere on that circuit - probably a loose wire nut, or if it’s a conduit system without a separate ground wire, a rusty/loose connection between the conduit and a box.
Answers to questions:
Yes, there are other things potentially plugged into the circuit. I didn’t even think about that. I’ll have to go back and measure again with everything unplugged.
No, all the outlets in the house aren’t like this, but all the outlets in the office are (and those are all on one run).
Romex vs conduit. The outlets in question are romex, as far as I know, but there is lots of knob & tube in the house, and I think there are parts where some knob & tube runs were extended with romex, so that could be the case here. I have yet to map out the whole house (and welcome tips on noninvasive ways of doing that). Frankly, I think the wiring in this house is pretty sketchy.
Yes, I have basic multimeter competency. 
It’s on the 0-250 scale, and it’s going to 60 on that scale. I have also verified that other outlets in the house behave as I would expect (120 from hot to neutral and hot to ground, 0 from neutral to ground).
The reason I was testing the outlet was because I was investigating replacing a switch on my TV projector, and I wanted to measure the voltage and current on the switch first, to see if it was switching “mains”* or low voltage DC. I was getting 60VAC across the switch in the “off” position. I thought 60VAC was an odd thing to be using, so I started checking my premises to make sure I wasn’t going crazy. Lo and behold, it was coming from the outlet.
Assuming “wiggy” is the term for an analog multimeter with an actual needle that wiggles back and forth, I’m using a wiggy.
I have observed that the “newer” wiring in my house is inconsistently wired in that sometimes the hot is on the large spade and sometimes it’s on the small one. Presumably this was due to some do-it-yourself wiring by previous owners and should be corrected.
*What’s the American term for this? I’ve only heard europeans use “mains”, but I don’t know what I’m supposed to call it.
I am in shock. We use 240v here and everything thats been posted I can relate to, but we stopped doing things that way over 10yrs ago. Over here every workplace must have the mains tested every 12months with nothing less than an MT26A, that’s every power outlet. On top of that every single plug-in appliance, EPOD & extension lead that is ‘On-Site’ must be ‘Tested & Tagged’ at regular intervals with no less than a STCMKD unit. The use of a Multimeter for such things is a serious criminal offence, and in the case of a death you will find yourself looking at a ‘Industrial Manslaughter’ charge. By our standards once the MT26A fails a circuit you can then use a Multimeter to assist in isolating the problem, but it still has to be re-tested correctly. by the way once a ciruit fails it is Shut Down untill it is fixed, if yours is a small business that usually means that you can’t operate at all from that site. We take this very seriously.
Workcover suggests that you rip-out & replace the wiring, (would be quicker & safer), find out who did the work and start legal action immediately.
I’d like to ask you a question, over here all building contractors must have all their electrical equipment tested every month, we even put lovely little colour tags on the cords to tell you it is safe. No Tag = No Entry. what standards if any are employed where you are?
Wow. Where is “here” that has such aggressive testing? In the US, wiring is generally given a visual going-over by the inspector, and once a COA is given (certificate of occupancy) for new construction, that wiring is never inspected again unless someone pulls a permit to work on it in the future.
Other than the occasional government job, functional testing (as in your “megatest”) is just not done. At best, the electrician will plug in a pocket tester to ensure the receptacle is live.
Oh, and a wiggy is actually a brand name for a “solenoid” tester.
Finally, I’m from Chicago, but if you say “mains” to me, I’ll know what you’re referring to. About the only other term I can think of would be “line” or “line power”