Codes related to short to grounds.

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lunalilo

Member
I have a problem where there is up to five boards president 60 Hz on the house ground. A technician came and said that that voltage can back feed into diodes on certain PCB boards on appliances and ruin it if The ground voltage is higher than the diode handling voltage.

If the voltage with higher it could easily shock somebody if they touched any surface of the appliances, which the voltage is present on also.

However An electrician came and said that that’s normal. I have a hard time believing this and was wondering if there’s any NEC code related to this problem in terms of having to eliminate it before the work was done?


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lunalilo

Member
Forgive me my problem is there is up to 5 V 60 Hz on the ground. My speech to text isn’t working properly.


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ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
1) NEC 250.6 tells us objectionable current is illegal, and how to remove it, but not how to detect it. A clamp meter is the only tool that comes to mind. How are you metering for objectionable current on the equipment grounding conductor?

2) Class A, GFCI protected circuits will automatically trip near a 6mA current imbalance, if leaking thru paths to grounding or people.
 

ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC
You could try plugging equipment into a GFCI protected circuit, but electronic equipment radio frequencies are also known to randomly nuisance trip GFCI's.
 

lunalilo

Member
I measured the ground with one probe of my meter and I held the other probe in my hand while I stood on the floor and I’m reading the results of 5 V 60 Hz. I’m also putting one probe to a screw on the microwave or on the fridge and I stuck in the other probe inside of a Nother different ground receptacle and it’s reading the same thing or similar.


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lunalilo

Member
I appreciate all your responses, I’m just worried because I’m more into the electronic side and I do know that all the PCBs in electronics are tied in with the same ground on the residence. I just want to take care of this so nothing bad happens to my property.


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lunalilo

Member
I guess I’m not able to measure current with that meter. I’m only measuring the voltage.


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ramsy

Roger Ruhle dba NoFixNoPay
Location
LA basin, CA
Occupation
Service Electrician 2020 NEC

lunalilo

Member
Thanks for the reference i get the point. It already over my head at the moment it just sucks that its there after this renovation. Just wanted the electrician to fix it if its his responsibility to do so. Thank you!


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mivey

Senior Member
Make sure it is not utility NEV. NEV of 5 volts is certainly within range. Although the utility would like to keep it to a couple of volts or less that is not always possible.

You should not be getting a shock at 5 volts.

Have your electrician cut off your main and measure the service ground to a remote earth point.

Suppose the utility neutral is at 5 volts. The equipment should be bonded to the utility neutral and have the same neutral to earth (NEV) volts seen on its equipment ground. Bonding everything is the key.

If your 5 volts at the equipment is above or below the utility neutral and you are properly bonded, you have a fault or unwanted ground current. Check to see if it is related to your loads (if it goes away with your main turned off).

It could be coming from off site (like a fault on the neighbor's equipment running back to your site over water lines or communication lines). The electrician can trouble-shoot this for you for a reasonable fee.
 
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