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Equi=Core Hum & Other Issues

I’ve owned a Core Power Tech Equi=Core 1800 for 6 months. Recently the transformer has started to hum inside the chassis. It happens when components are on and also when sources are powered down. The transformer hum is intermittent. It ranges from multiple times per day to 3 or 4 days without any hum. I never had DC on my dedicated lines before, so I picked up a Klein Tools AC/DC tester... https://www.kleintools.com/catalog/electrical-testers/electronic-acdc-voltage-tester-12-240v-ac-15-2...
and when plugged into wall receptacles it indicated overload. Line voltage is steady at 122VAC and always has been.
What am I doing wrong, and how should I test for DC on the power line?

I discovered another problem when testing the Equi=Core duplex receptacles; they indicate inverted polarity. All house outlets measure correct polarity.
I’m looking for some assistance in diagnosing this hum. I’m not sure if it’s due to DC offset or if the torroid itself is vibrating in its mounting.

I know this is becoming a long thread, but I must mention that the Equi=Core now trips the breaker at the panel when powered on. It trips several times in a row, eventually allowing power-up. This is a 20A dedicated line from a subpanel which I’ve had for years.
Any advice is much appreciated.


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Showing 2 responses by cleeds

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cleeds
5,717 posts
 
lowrider57
... the corrosion in my meter box is causing distortion in the mains.
That's potentially hazardous. Your electric utility should install a new meter and/or meter pan, as needed.
 Does anybody know if a toroidal transformer can be damaged due to longterm hum from harmonic distortion?
That seems unlikely.
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cleeds
5,717 posts
 
lowrider57
Unfortunately, the homeowner is responsible for the maintenance of the meter pan and meter drop onto the property. There’s a water leak in the conduit from my roof down to the meter and the seal into the pan has worn away.
Wow, I am really sorry and surprised to hear that you have to pay for that. Is your utility not willing to share the expense with you? Perhaps they are blaming the maintenance for the whole problem, but that does not really seem fair to me. Its equipment should be able to withstand weather.

Are you in the US? If so, you may want to consider filing a complaint with your state’s Board of Public Utilities (or whatever its equivalent is) to recover some or all of your costs. It might be worth the effort.

I know from experience that my electric utility is responsible for the meter and the meter pan. I do have underground electric service, so that may explain the difference.

With an aerial drop, I think the utility might be able to claim that its responsibility ends at the drop, not the meter. In that event, maybe your homeowner's insurance might provide some coverage?
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