Is there a potential earth leakage or is it something else?

[HVManiac]

I'm facing an electrical issue in my house since last Christmas. When the lights or appliance with motor in any room are turned off/on the TV would go out and come back on in a short span (as if the power went out and came back in a second). I recently had some mishaps where my two older PCs PSU blew up. But I though --- was just the old PSUs had its end of life. Then recently my new under one month old PSU in new PC built just died.

So, I took my multimeter and checked the voltages first from a 220V kitchen outlet that is directly wired from the panel next room and it shows Phase-Phase=223V & both Phase-Ground=220V. Then I tried the other 110V outlets in the house and they all have Neutral-Phase 130V, Neutral-Ground=0.4V & Phase-Ground=49.2V. Next trying other 220V outlets also gave Phase-Phase=223V and both Phase - Grounds=49.2V. So, except for the 220V outlet directly from the breaker in the kitchen something is off. Anyone here can help me out with what could be the potential situation? Because of this pandemic situation I have held off calling an electrician until now.

 

[Megawatt]

I'm facing an electrical issue in my house since last Christmas. When the lights or appliance with motor in any room are turned off/on the TV would go out and come back on in a short span (as if the power went out and came back in a second). I recently had some mishaps where my two older PCs PSU blew up. But I though --- was just the old PSUs had its end of life. Then recently my new under one month old PSU in new PC built just died.

So, I took my multimeter and checked the voltages first from a 220V kitchen outlet that is directly wired from the panel next room and it shows Phase-Phase=223V & both Phase-Ground=220V. Then I tried the other 110V outlets in the house and they all have Neutral-Phase 130V, Neutral-Ground=0.4V & Phase-Ground=49.2V. Next trying other 220V outlets also gave Phase-Phase=223V and both Phase - Grounds=49.2V. So, except for the 220V outlet directly from the breaker in the kitchen something is off. Anyone here can help me out with what could be the potential situation? Because of this pandemic situation I have held off calling an electrician until now.

It sounds to me like you have an neutral problem since your phase to phase is correct but phase to neutral is what’s given problems. Since it seems to be all your 120vac receptacles so I would start in the panel and please be careful electricity kills. Good luck

 

[pc1966]

So, I took my multimeter and checked the voltages first from a 220V kitchen outlet that is directly wired from the panel next room and it shows Phase-Phase=223V & both Phase-Ground=220V.

I thought the USA arrangement has the supply as 110-0-110 with the neutral grounded, so should you net be seeing 110V from each phase to ground (also to neutral)?

Beware of multimeters though, not all are rated for high energy circuits (look for a rating such as CAT-III or CAT-IV at 250V or more) and they will show volts with an open (floating) conductor simply due to capacitive currents as their impedance is typically around 10M ohm. Also if you set them to the wrong range it can end very badly with bang (on current) or not seeing AC energised (if on DC volts).

Usually electricians over here would have a dedicated "voltage tester" for initially checking for power, something like this that does one job, but does it well. Here is an inexpensive example:

https://www.homedepot.com/p/Klein-Tools-AC-DC-Voltage-Tester-ET45/308822920

You really should have one!

Certainly it sounds like problem with your neutral as Megawatt has already said, and if you can (carefully) check it at the distribution board you should see if it is a wiring fault in your house or something for your power company to fix.
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The fact your kitchen outlet looks right means your panel must be OK, so there is some fault in the neutral for the other sockets. Most likely it is a bad connection somewhere, possibly even where the wires join the neutral bar in the panel.

You should be able to cut the power to most of the panel, but like you i am very wary of removing covers on systems that are energised all the time!

The issue with the multimeter is more that they can show volts when a cable is open due to the high measurement impedance. For example to see 40V only needs 4uA flowing on a 10M meter, and from 110V somewhere that is 17.5M so for 60Hz you would see it from 152pF which is about 1m length of PVC insulated wires side by side!
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Oh, your post has vanished!

 

[HVManiac]

I thought the USA arrangement has the supply as 110-0-110 with the neutral grounded, so should you net be seeing 110V from each phase to ground (also to neutral)?

Beware of multimeters though, not all are rated for high energy circuits (look for a rating such as CAT-III or CAT-IV at 250V or more) and they will show volts with an open (floating) conductor simply due to capacitive currents as their impedance is typically around 10M ohm. Also if you set them to the wrong range it can end very badly with bang (on current) or not seeing AC energised (if on DC volts).

Usually electricians over here would have a dedicated "voltage tester" for initially checking for power, something like this that does one job, but does it well. Here is an inexpensive example:

https://www.homedepot.com/p/Klein-Tools-AC-DC-Voltage-Tester-ET45/308822920

You really should have one!

Certainly it sounds like problem with your neutral as Megawatt has already said, and if you can (carefully) check it at the distribution board you should see if it is a wiring fault in your house or something for your power company to fix.

Thank you for the reply. Yes, you are right we have 115-120V from power company. In the 220V kitchen outlets directly wired from the panel I'm getting 113.4-0-113.4V when I checked just now. But in all the other 220V outlets in my other three rooms are giving me Phase-Phase=223V and Phase to grounded neutral=50V. Same thing with the 115V outlets in the kitchen and the other three rooms.

I checked with my UNI-T UT33C multimeter first. It's a CAT III they say but it is not a dead cheap meter either. I confirmed my findings with an Omega Multimeter borrowed from my workplace also. This one is a $700 good meter so I guess we can trust it.

I am an electronics engineer but apart from simple things like changing receptacles, light fixtures I'm not very comfortable with mains. Especially from the panel where power can't be shut. I will be calling a certified electrician and get it checked out asap.
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It sounds to me like you have an neutral problem since your phase to phase is correct but phase to neutral is what’s given problems. Since it seems to be all your 120vac receptacles so I would start in the panel and please be careful electricity kills. Good luck

Thank you for the reply. I am not very comfortable with diagnosing mains electrical without turning the power off. Since this has to be done from the panel I'll leave it to an electrician to find out the issue.

 

[Megawatt]

I thought the USA arrangement has the supply as 110-0-110 with the neutral grounded, so should you net be seeing 110V from each phase to ground (also to neutral)?

Beware of multimeters though, not all are rated for high energy circuits (look for a rating such as CAT-III or CAT-IV at 250V or more) and they will show volts with an open (floating) conductor simply due to capacitive currents as their impedance is typically around 10M ohm. Also if you set them to the wrong range it can end very badly with bang (on current) or not seeing AC energised (if on DC volts).

Usually electricians over here would have a dedicated "voltage tester" for initially checking for power, something like this that does one job, but does it well. Here is an inexpensive example:

https://www.homedepot.com/p/Klein-Tools-AC-DC-Voltage-Tester-ET45/308822920

You really should have one!

Certainly it sounds like problem with your neutral as Megawatt has already said, and if you can (carefully) check it at the distribution board you should see if it is a wiring fault in your house or something for your power company to fix.
[automerge]1591436193[/automerge]
The fact your kitchen outlet looks right means your panel must be OK, so there is some fault in the neutral for the other sockets. Most likely it is a bad connection somewhere, possibly even where the wires join the neutral bar in the panel.

You should be able to cut the power to most of the panel, but like you i am very wary of removing covers on systems that are energised all the time!

The issue with the multimeter is more that they can show volts when a cable is open due to the high measurement impedance. For example to see 40V only needs 4uA flowing on a 10M meter, and from 110V somewhere that is 17.5M so for 60Hz you would see it from 152pF which is about 1m length of PVC insulated wires side by side!
[automerge]1591436253[/automerge]
Oh, your post has vanished!

PC1966 please everyone always says we have 110vac. Our voltage is 240/120. I can understand why people over hear call it 110 vac and depending on the POCO I’ve seen it as high as 245/123 vac and I have a fluke 787 process meter that I do my work with. People over hear that call it 110vac are saying that out of habit I guess. Have a great day ?

 

[pc1966]

PC1966 please everyone always says we have 110vac. Our voltage is 240/120. I can understand why people over hear call it 110 vac and depending on the POCO I’ve seen it as high as 245/123 vac and I have a fluke 787 process meter that I do my work with. People over hear that call it 110vac are saying that out of habit I guess. Have a great day ?

Yes, a bit like the UK is officially 230V (+10% -6%) but in fact many places are on 245V nominal and have been for decades!

Enjoy the weekend

 

[Megawatt]

Yes, a bit like the UK is officially 230V (+10% -6%) but in fact many places are on 245V nominal and have been for decades!

Enjoy the weekend

Thanks PC what can I say, we have a lot of cowboys over here