A few weeks ago I had a surge protector installed in my breaker panel.
It was a new variey I had not seen before, in that it took the place of two standard sizede breakers and connected to both phases of the breaker panel supply
Since then we’ve had had a couple of power outtages and all the household devices kept running upon power restoraton - so far so good :-)
This past week I had reason to disconnect power and speaker cables to loan to a friend for audition.
Afterwards I reconnected the power cables to the amp and powered up.
NOTE: the system is on a dedicated line - it’s breaker was not touched by the install
Immediately I noticed a hum from the amp, where previously there had been none - even at full volume with the phono stage selected.
After lots of analysis and testing, I remembered the installation of the Surge protector.
I measured the impedance between the ground and the neutral and found around 5 ohms of resistance.
To temporarily get over the hum I have connected the neutral side of the inputs to a common earth tap on the power distribution box - it has worked like a charm - i.e. until I can get the electrician back here to fix the real issue.
So my question: - Is this just sloppy work? - I’m assuming that the neutral of the dedicated line was disconnected and not reconnected correctly, OR - do ALL housewide surge protectors such as the one I have had instlaled always present with this problem?
The surge protector you had installed does not affect the ground, itself. It's a good thing, and if you are going to use these types of surge protectores (parallel mode) the panel is exactly where it should go.
However, you definitely have a ground lift problem and should have it looked at. Not sure when or how it happened though. Lots could do this. It could be during a storm the ground to neutral connection broke or got severely degraded, or it could be something unique to that line.
@dweller My condolences, but the ones I know of don’t trip. There is no breaker on them to trip and reset. They may however go out and need replacement eventually.
If you turn off the 2 pole breaker in the electrical panel the SPD (Surge Protection Device) is connected to, the SPD will be disconnected, isolated, from the electrical panel.
That is not how this type of surge protector is connected, if it is what I'm thinking of, like this model:
It's impossible to tell from the pic, but the surge protector itself takes 2 spots. In this way it is just like a 2-pole breaker. It connects directly to both phases with no interceding breakers. There is a tail to be attached to the panel's neutral.
In short, there is no breaker on the protector, and no breaker that is assigned to power the protector either. Should the surge protector itself short the panel's main breaker will have to trip.
There's no way for a homeowner to "turnt it off" short of removing the panel cover and pulling it off the panel.
Also, because of the way in which this type of surge protector connects , it is NOT possible for it to lift the ground like the OP has measured. It has nothing to do with ground.
It might be possible the electrician did something while installing it, or more likely, that something has gone bad independently of this. The way this works is that the neutral and ground may only tie together at 1 point in the entire home. So, it could be a disconnected ground or neutral anywhere from the listening room back to the service entrance.
FYI-I have had a whole house surge for 15 years. It only trips on very large spikes such as a transformer blowing at the pole. Smaller spikes always get through. Also, even with big spikes it is not nearly as sensitive as even the lower priced PS Audio stuff. You should still use either a conditioner or surge at your system. Several times I have had my PS blow while the whole house did not. There is nothing wrong with my whole house surge, it just wasn't designed for expensive audio.
@erik_squires - Thanks for the sympathy. After giving it some thought, I think it was a whole-house GFI (ground fault interrupter) not a surge protector. It would pop open at least once a day.
@dweller - Interesting. A whole house GFI sounds like a pain the butt! Any bad actor in the house could cause it. Individual GFI or now, arc detectors, however, save lives. :)
FTR, there are all sorts of devices you can plug into an electric panel. I'm by no means an expert. I just happen to know what I think the OP is talking about. :)
Thanks guys - the surge protector that is installed has an LED idicating it is operational. If there is an issue the LED goes out. There is no way to turn it off..
I'm pretty sure there is an issue with the neutral or ground conenctions, so I will take a look at them first.
I have had a similar hum with a consumer DVD player and my NAIM amp - it seems that NAIM has a particular design approach that seems to highlight grounding issues.
I've since installed a ground between the neutral side of the inputs and the ground of the mains supply - this made the amp completely silent (i.e. quieter than before the SP was installed) - BONUS :-)
I'll still check the neutral/ground, but I will then assess the need for the new grounding scheme.
One thing I did notice after the SP install - my home network/TV Streaming became much more reliable.
I've since installed a ground between the neutral side of the inputs and
the ground of the mains supply -
Not a good idea. Also against NEC electrical safety code. The neutral can only be bonded, connected, to earth ground at one point, the main electrical service equipment. What you have done by connecting the neutral to ground again at the branch circuit wiring is to create a parallel path for load neutral current to return to the electrical panel on the equipment grounding conductor. .
You may have exactly one bonding point between neutral and ground. However, you may (and may have to!) have multiple ground rods which are connected to each other. That does not allow you to connect neutrals willy nilly to your ground rod "farm" though. You may still only have one bonding point.
I think I did not explain myself properly... - I did not make any changes the bonding points of the neutral and ground in the breaker panel. - I simply took a wire from the "neutral side" of the inputs on the amp and grounded it to the ground point on the power bar in my audio rack
Anyhow - that has since been removed
Turns out - all that was required is a slight "repositioning" to a couple of the wires in the breaker panel. - the electrician had repositioned a couple of breakers and those live wires ran paralell to (and was touching) the neutral wire of the cable run for my dedicated audio outlet - He just moved the wires to put a little more space between them - the hum disapeared.
I think I did not explain myself properly... - I did not make any changes the bonding points of the neutral and ground in the breaker panel. - I simply took a wire from the "neutral side" of the inputs on the amp and grounded it to the ground point on the power bar in my audio rack
Yes, I did understand you. You connected the neutral conductor to the equipment ground/equipment grounding conductor at the power bar at the audio rack.
The neutral conductor is a current carrying conductor. In the case of a two wire circuit the neutral conductor (The Grounded Conductor) will carry the same amount of current as the HOT (The Ungrounded Conductor). If there is a 5 amp connected load on the Hot conductor there will be 5 amps on the neutral conductor.
When you connected the neutral conductor to the equipment ground you provided a parallel path for the current to return to the source, the electrical panel. You made the equipment ground/equipment grounding conductor a current carrying conductor. That can dangerous...... If the equipment grounding conductor is of the same wire gauge and made from the same metal then it will theoretically carry half the current in the circuit as the neutral conductor did before you connected the neutral to it. So if using 5 amps as an example, when you connected the neutral conductor to the equipment ground/equipment grounding conductor there was 2 1/2 amps on each of the two conductors.
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