Line fault at the outlet -- do I need an electrician?

Yesterday, I got a Panamax, Max 1500 surge protector and line conditioner. (I got a very good deal on it, and am just trying it out.)

I plugged it into an outlet I've been using for a while and one of the red lights on the front lit up saying "line fault." (I'm not sure how this is different from a "ground fault." Maybe it's the same.) The Panamax does not do this with other outlets in the room. They seem ok.

So, I know this means that the outlet is improperly wired. My question is, might this be a simple thing to check and/or fix? Any suggestions most appreciated. It's the only outlet I can use to have my audio set up where I usually have it. Now is not an optimal time to call an electrician. If this is a big problem, I'll try out my gear somewhere else in the room, but if I can fix this without too much expertise, that would be ideal.
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Got it. All those are good questions, but I think the ultimate solution is to delegate this whole thing. But now I know what to ask the professionals. This amateur is sticking with writing and teaching. Thanks again.
"I remeasured the outlet. Here are the readings that I got:
Ground to neutral slot equals 121.6ground to hot slot equals 3.6
neutral to hot equals 124.6Hot to neutral equals 124.6"
- Hot to Neutral 124.6   (let's call Hot - Line .. more typical term)
- Ground to Neutral Slot 121.6- Ground to Line Slot 3.6
I assume this measurement was made with almost everything turned off?
Hot-Neutral is 124.6 ... or about the same as Ground-Neutral + Ground-Line.  With a noise-free reading, (G/N) + (G/L) should approximately equal the source voltage at your electrical panel AND and should be higher than what you measure L-N at the outlet.

(G/N) + (G/L) = 125.2 - Or perhaps the voltage at the panel(L-N) = 124.6 - Or the voltage after all the drop(G/N) + (G/L) - (L-N) = 0.6

However, as stated G-N should be close to 0, but often is not due to drops in the wires (and noisy measurements). Given you have 3.6 with what appears a very small drop on L-N, that suggests either a noisy measurement (possible), OR, it could be a faulty ground connection on that line. Given the wiring issue already noted (and DIY nature), I would be investigating the ground integrity. Fortunately, you can do this yourself.

1) Turn the breaker off!!2) Wait 30 seconds (any leakage from capacitors in power supplies)3) Ensure the L-N, G-L and G-N voltage is 0.  I am expecting G-N is 0, but if it is not really close with power disconnected, that is an interesting result. If it is no 0 or really close, DO NOT CONTINUE!
4) Repeat step 3! ... you really need to be sure.5) Put your multi-meter on the ohms setting.6) Measure the resistance between the Ground and the Neutral (the ones that was measuring 3.6 volts). It should be <1 ohm with a good contact between the probes and the socket.
Thanks for that process. It sounds like this test does not require me taking the outlet out --just testing the ohms with the multimeter. That doesn't seem very unsafe, but I'll follow instructions carefully if I do it.

Your circuit is fed from a sub panel, correct?  Is the circuit fed from an independent breaker, or is it a duplex?

Also, have you seen any boxes in  between the sub panel and the outlet?


Lastly, does the 4V on the neutral go away when the breaker is off?