Why is a 1.5-2 volt AC signal on my Neutral line?

Oops. Meant to say ground rod, not ground road.

Blindjim,

A difference of potential, voltage, measured at an electrical outlet measured from the neutral to the equipment grounding conductor can be the result of VD, voltage drop, on the loaded neutral conductor. If the resistance of the equipment grounding conductor is less than the resistance of the loaded neutral conductor then there can and will be a difference of potential between the two conductors.

VD is directly proportional to the size, length, and load placed on the conductor.
Poor connections along the length of the conductor can cause higher resistance in conjunction to the amount of load placed on the branch circuit neutral as well.

As Simply_q said in his post the main service earth ground connection does not come into play. In most cases the branch circuit neutral conductor as well as the branch circuit safety equipment grounding conductor terminate on the same neutral/ground bar in the main electrical service panel.... Sub panels will have them separated on two different bars but they still end up tied together at the main service electrical panel via the feeder neutral conductor and equipment grounding conductor. Both connect together at the main panel.

Jea48

“most cases the branch circuit neutral conductor as well as the branch circuit safety equipment grounding conductor terminate on the same neutral/ground bar in the main electrical service panel.... Sub panels will have them separated on two different bars but they still end up tied together at the main service electrical panel via the feeder neutral conductor and equipment grounding conductor. Both connect together at the main panel.”

Yeah… I know… I said that already. See above. I’ve installed services for both industrial and residential… for years. Years ago.

The OP said this issue happened right after he added another (new?) amp.

Things were ok BEFORE I GUESS.

So one should always look at the last thing (s) which were altered or changed, to find the answer for a problem…. If indeed a problem came as the result of that change. Apparently there is/was an issue following the amps addition to the system.

I had a similar incident a few years back when I added a near new amp, and thereafter a brand new amp. Two in fact. The ‘hum’ I experienced was attributed to the grounding system in my home. Not the amp (s).

Consequently I said what I said for a reason. Maybe we ought to call Ripley’s Believe it or not’, here.

Ultimately I had to lift the ground from the dedicated ckt (s) driving the amp (s). Further, I had to also mitigate the CATV connection to the service ground by use of a transformer as mentioned above, as BOTH ITEMS introduced issues to the system. Even though as the OP said too, my CATV was not connected to my then stereo system.

It is however connected somewhere else.

It was connected to the service ground at the power pole, and et al, above… everything gets tied together there… neutrals and commons.

Sometimes an issue has one thing causing the problem, sometimes it’s predominately one thing that makes you notice it, but sometimes there are also other contributing factors which only raise their heads once the issue is reailized.

The CATV connection outside shouldn’t have matter possibly but it did.

In some areas around here some counties make new construction employ two different ground rods. There’s always the risk then of acquiring a difference of potential there. In sandy conditions drainage is severe, reducing the actual ground rod conduction with the earth itself. Rods longer than the eight foot norm would work better perhaps, but I’ve seen the value of keeping that area surrounding the rod damp or wet. Especially in times of extended drought or no rainfall.

Sometimes electrical issues defie practical or common sense approaches. So I tend to keep a more open mind and not merely stick strickly to imperical wisdom.

When the electrical contractor I worked for got the contract to build the local Honeywell location, we ran across a problem with numerous ground rods and a variety of ckts. All the rods were in one common area. All solid copper. All 10 or 12 ft long. Some of the ckts wound up with hums. Front to back several times we went thru the ckts finding nothing out of the ordinary. By then the surrounding area had been poured and there was no way to remove the rods … only to relocate them. Instead of reworking all the rods with another install, someone, one of the older sparkys came up with the DIY inductor.

We all had a good laugh at his expense when he told us about it. BUT it worked fine after a few tries. I don’t think anyone ever told Honeywell what we actually did to fix the situation though.

So I don’t just make this stuff up. Believe it or not.

Regardless, I hope things get figured out… one way or another.

You have a ground loop issue. Neutral is grounded at the main electrical panel box however the length of cables and a poor contact somewhere (or a cheater plug) to the equipment can allow a small stray voltage to build up from some power supply leakage to ground (coudl be a faulty component). An RC interconnect will provide the return for a small stray current and hence you will induce a hum in the line level signal. With RCA you always have this problem to a greater or lesser degree - although the hiss or hum may often be low enough not to be of significance in a system with low dynamic range.

Guys, I think we need clarification from the op, as I implied in my earlier post and as Jim requested. My suspicion is that the reference to 1.5 to 2.0 vac on the "neutral line," on some components only(!), does NOT refer to the ac neutral.

For one thing, he referred to "the neutral side of the interconnect." Also, how would he be able to measure the voltage between ac neutral and ac safety ground individually for each component, without opening it up and probing internally under the chassis?

So as I indicated in my earlier post, I suspect he is referring to an ac voltage between circuit ground (as measured on the ground sleeves of rca connections) and ac safety ground. As Jim and I indicated earlier, if he is seeing a significant difference among those readings for different components, while the components are interconnected, he's either got a defective interconnect or a defective circuit ground connection on one or more of the rca jacks. Either of which could certainly account for a hum problem.

Best regards,
-- Al