Requesting advice/help from an Electrician?

[Pepi93]

Greetings,

I've been trying to troubleshoot this issue for some time and I believe I have narrowed it down to ask the right questions.

My PSU and UPS (Cyberpower PR1000LCD) coil wine/buzz sometimes. It could be in the evening, or a day later, or all day sometimes. It could also not happen for a few days straight.

I believe I've narrowed it down to the circuit which powers my PC room. I've checked all the plugs on the circuit and have found no faults and my UPS also doesn't indicate any wiring faults. The building is about 40 years old but my breaker box was installed instead of the old fuse box within the last 8 years.

I've now stretched a extension cord and powering my PC from a different room. There is minimal if any coil wine/buzz so it seems to be specific to the circuit that powers my PC room.

What could it be?

 

[trents]

Is your Cyberpower UPS capable of powering your whole system for a few minutes?

One test I think you need to do is to wait until a time when you are experiencing coil wine and then unplug the Cyberpower from AC so that the system is running off of the UPS. If you do that does the coil whine immediately stop?

 

[EarthDog]

Logic tells me if it was the circuit, other products would be doing it as well. If nothing else is doing it and directly plugged into the socket, then I would look elsewhere.

 

[Dolk]

Like ED is suggesting, is there anything else odd happening on that circuit? What is the total current being pulled on that current? How old is the circuit?

I think the UPS is kinda doing it's job. Whine occurs when the inductor is taxed, so it sounds like it is working overtime to meet some sort of load demand. Since this is an In-line AVR type, I'd say it's working hard to balance the output load and not charge the battery.

 

[Pepi93]

Today there is no wine/buzz...on that circuit.

Yesterday there was a lot to the point that I got the extension out and tried a different socket in the apartment.

I've tried plugging directly into the socket without UPS and PSU was buzzing yesterday and unplugging the UPS activates internal fan which is loud so can't hear anything else.

My system draws around 225w-250w and a bit more when gaming, UPS can handle 700w

The only other things I have plugged into this particular circuit are my modem/router, a TV box and whatever I'm charging, phone, laptop etc...

 

[Lochekey]

Have you tested the outlets on that circuit with a DMM. What type of voltage are you seeing line-neutral and line-ground. I would also check to see if you get any voltage from neutral-ground. If possible I would also check the line-neutral reading on a circuit on the other leg of power as well as line-line voltage on the two legs.

I would be interested to know what all is on the computer room circuit as well as what other loads share the same leg as that circuit.

I would try to take these readings when there is no coil whine and then repeat them when there is coil whine.

 

[Pepi93]

Have you tested the outlets on that circuit with a DMM. What type of voltage are you seeing line-neutral and line-ground. I would also check to see if you get any voltage from neutral-ground. If possible I would also check the line-neutral reading on a circuit on the other leg of power as well as line-line voltage on the two legs.

I would be interested to know what all is on the computer room circuit as well as what other loads share the same leg as that circuit.

I would try to take these readings when there is no coil whine and then repeat them when there is coil whine.

I need a dictionary to understand what you're saying

I do have a DMM (digital multimeter?), just have to figure out what line-neutral, line-ground, neutral-ground, leg of power, line-line voltage and two legs means and then I'm good to go.

On the computer room circuit I have a TV box, modem/router, light switches, ceiling fans, 1 per room, and the odd gadget that I charge, cell, laptop etc.

I did test the outlets at some point with a DMM and didn't see any irregularities. My UPS also reports the voltage and I've checked it during both occasions and didn't notice a difference.

 

[Alaric]

Have you checked what else may be on that circuit? It may be worth flipping that breaker and checking around the house to see if anything else is off.

 

[Pepi93]

Have you checked what else may be on that circuit? It may be worth flipping that breaker and checking around the house to see if anything else is off.

I've done that. I know what exactly is on that circuit. I also never change the items that are on it. The circuit powers two rooms. Room 1 is my PC room with TV box, modem and not much else other than lights. Room two is my bedroom and in there I have a air purifier and humidifier. Humidifier is on at night (it's small) and everything else is off and air purifier is on when I'm not home and everything else is off.

 

[Dolk]

Pepi, which DMM do you have? Upload a pic. Before plugging into outlets and possibly causing harm, lets walk through what you should be doing. We need to make sure the DMM can handle the circuit you have up in Canada.

What is the standard voltage for your housing up there?

 

[Lochekey]

Pepi, which DMM do you have? Upload a pic. Before plugging into outlets and possibly causing harm, lets walk through what you should be doing. We need to make sure the DMM can handle the circuit you have up in Canada.

What is the standard voltage for your housing up there?

Crap I did not realize he was in Canada, nice catch Dolk. Definitely need to know the electrical system be employed to make a better diagnoses.

 

[||Console||]

@ dolk we have the same 124/240 60hz system that you guys do ( we share 90+% of code as well but ours tends to lag yours by a few years)

@ op Does this only happen when the Ceiling fan is on ? Motors can induce unballanced load onto the neutral ( White wire)
Is this on a arc-fault breaker ?( might say AFCI on it as well as a test button )
Neutral = white wire
Line = the black (maybe a red)
is there a Ground in the box and on the plug ? ( bare copper wire)
Turn off that CCT and take all the plugs off and check the Whites and the Blacks to make sure all are tight , also that the ground isn't touching the white on any of the plugs . Check that the plactic on the plugs isn't turning black anywhere from to much heat .
When you tested the plug what was the voltage reading ?
Test Black to ground
White to black
White to ground

You say apartment so im guessing you have a load center PNL ( no main breaker @ the top to turn every thing off ) Are you competent enough to open the PNL and check the that Black and white for that CCT are tight ?
You could also try a different breaker .

Is your meter a clamp on ? or just have 2 probes ?

 

[Pepi93]

@ dolk we have the same 124/240 60hz system that you guys do ( we share 90+% of code as well but ours tends to lag yours by a few years)

@ op Does this only happen when the Ceiling fan is on ? Motors can induce unballanced load onto the neutral ( White wire)
Is this on a arc-fault breaker ?( might say AFCI on it as well as a test button )
Neutral = white wire
Line = the black (maybe a red)
is there a Ground in the box and on the plug ? ( bare copper wire)
Turn off that CCT and take all the plugs off and check the Whites and the Blacks to make sure all are tight , also that the ground isn't touching the white on any of the plugs . Check that the plactic on the plugs isn't turning black anywhere from to much heat .
When you tested the plug what was the voltage reading ?
Test Black to ground
White to black
White to ground

You say apartment so im guessing you have a load center PNL ( no main breaker @ the top to turn every thing off ) Are you competent enough to open the PNL and check the that Black and white for that CCT are tight ?
You could also try a different breaker .

Is your meter a clamp on ? or just have 2 probes ?

Let's see what I can answer here...

1) Ceiling fans are on all the time, just different direction for winter and summer
2) no arc fault breakers on my outlets, just regular outlets
3) There are ground wires inside the receptacles. I've checked all plugs because I was trying to troubleshoot brownouts that were happening during Christmas. They have since not happened again so no idea there and they only happened twice in a span of 24 hours.
4) My breaker box is in my unit but I'm not going to open it up. I can flip breaker switches on/off as I please and that's how I troubleshoot things when I have to.
5) I have a regular mastercraft digital multimeter with two plug in wires
6) When I was doing readings of the plugs with the DMM I was getting normal values of 120v ish...My UPS reads 122-124v and I haven't had any buzzing since 2 days ago. These readings don't change.
7) When I checked all the plugs, all wires were snug/tight, no signs of any black/burned or scorched areas. All wires except for the ground in some cases were insulated and not bare. No wires touching etc. I also checked heat behind walls just by running my hands across the wall all over the room.
8) no idea what a CCT is but I think I did what you're asking me to do in point 7. I did this over Christmas break. All was good
9) DMM is not clamp on, just two probes



Not my hands, but this is what I have



My breaker box.



This is what I see when there is and isn't buzzing, no faults detected and no change in power coming from the outlet.

 

[||Console||]

Let's see what I can answer here...

1) Ceiling fans are on all the time, just different direction for winter and summer But if you turn it off ( like pluging into the other cct (circuit) ) acts like does the bizing go away ?
2) no arc fault breakers on my outlets, just regular outlets arc faults are a special breaker not a Outlet and no you dont have any(
3) There are ground wires inside the receptacles. I've checked all plugs because I was trying to troubleshoot brownouts that were happening during Christmas. They have since not happened again so no idea there and they only happened twice in a span of 24 hours.
4) My breaker box is in my unit but I'm not going to open it upto check the source of that branch CCT you should or hire someone. I can flip breaker switches on/off as I please and that's how I troubleshoot things when I have to.
5) I have a regular mastercraft digital multimeter with two plug in wires Ok no clamp on if you Did I was going to have you check the amps of that CCT
6) When I was doing readings of the plugs with the DMM I was getting normal values of 120v ish...My UPS reads 122-124v and I haven't had any buzzing since 2 days ago. These readings don't change.
7) When I checked all the plugs, all wires were snug/tight, no signs of any black/burned or scorched areas. All wires except for the ground in some cases were insulated and not bare. No wires touching etc. I also checked heat behind walls just by running my hands across the wall all over the room.
8) no idea what a CCT is but I think I did what you're asking me to do in point 7. I did this over Christmas break. All was good (CCT is Circuit
9) DMM is not clamp on, just two probes




This is what I see when there is and isn't buzzing, no faults detected and no change in power coming from the outlet.

Can you check from white to ground for me ?

 

[Lochekey]

If this is an apartment I am going to assume that you have a shared main drop that is then split at a main distribution panel/meter box before being fed to each apartment.

I can not make it out from the picture but it does not look like a pass through panel so I assume that you are not sharing mains with a neighbour.

Depending on how the power distribution is set up in your apartment building a load on one leg of the circuit in one of the other apartment could be causing an abnormality on that circuit.

As Console mentioned try checking neutral-ground(white-green normally) and see if there is any voltage present.

- - - Updated - - -

I'm assuming you have typical nema 5-15 outlets so reference the diagram above for proper read points.

 

[Pepi93]

Can you check from white to ground for me ?

If I'm going by the pictures above, my plugs are the top left of the first pic. I got no reading, when going white to green (as is the color coding above), doesn't matter if red or black wire is used from MM. From White to Black, I got 125v and the UPS is buzzing but it's a nice constant buzz and my PSU doesn't seem to be affected.

UPS also detects 125v

 

[Lochekey]

Does it always happen when the voltage gets up to the 124+ volt range. Is the ups attempting to employ voltage correction circuitry that is causing the coil whine maybe?

 

[Pepi93]

I don't know what the UPS is doing or not doing but even before I had it my PSU would sometimes coil wine/buzz and sometimes not.

Whatever is causing this effects both units together or independently. The UPS has Input voltage Sensitivity which I have set to low and UPS will intervene if voltage dips below 102 or higher than 131. These are default settings.

I will keep an eye out but now it's at 124v and still buzzing but quietly, which doesn't bother me. I'll see what happens if it hits 123v.

 

[||Console||]

If this is an apartment I am going to assume that you have a shared main drop that is then split at a main distribution panel/meter box before being fed to each apartment.

I can not make it out from the picture but it does not look like a pass through panel so I assume that you are not sharing mains with a neighbour.

Depending on how the power distribution is set up in your apartment building a load on one leg of the circuit in one of the other apartment could be causing an abnormality on that circuit.

As Console mentioned try checking neutral-ground(white-green normally) and see if there is any voltage present.

- - - Updated - - -

I'm assuming you have typical nema 5-15 outlets so reference the diagram above for proper read points.

Just a FYI most appts I have worked in here come from main service pnl to a tap box than branch out to a stack of meter base's . Never seen a pass through system Like you were talking about .

 

[Pepi93]

So from what I'm understanding, the next time I'm experiencing this annoying buzzing, I need to check the neutral-ground to see if there is any voltage present?

I do think that there's a main service box somewhere in the building and it feeds all of our units and then we each have our own breaker box as I showed in my picture above.

Also thank you to everyone for contributing to this discussion/troubleshooting and teaching me a few things.