# neutral to ground voltage at copier machine



## tersus (Jul 3, 2012)

When the copier/printer machine runs or kicks on when first plugged in, I get neutral to ground voltage of around 2-3 volts at the receptacle. The company that services the customer's machine insists that its not a problem with there equipment--apparently this machine can only tolerate a n to g voltage of less than 1 v, and for every three months or so that the voltage exceeds that, they have to come out and service it. The service company told me that in similar situations in other buildings the electrician just had to find some loose grounds and tighten them up. I've checked connections from the circuit to the panel and to the MDP and everything looks good. Here's some more information that may or may not be relevant:
- n to g voltage when the machine isn't running stays at .5 v
- n to g voltage at the panel when the machine is running jumps from .5 v to .8 v
- plug the machine into another circuit fed from the same panel and you get the same result
- the machine isn't on a dedicated circuit, but just being curious, I tied in a receptacle off the panel and ran an extension cord over to the machine (about 30' away) and the results were worse as it jumped to almost 4 v at times. 
-the service company brought another machine over in it does the some thing, even took it to the other side of the building (closer to the MDP) plugged it in to a receptacle fed from another panel and the results were 'worse'. They didn't tell me how much worse, though. 
-based on my readings, I don't see how voltage drop could be an issue. 
It's a 3000A service in the basement, the bond to the water looks as it should be--there's a lot of corrosion at the main switch where the lugs are attached to the bus. Regardless of the copy machine issue we agree that this is something that needs to be cleaned up and fixed, hopeful that it takes care of the problem. Shutting down the service to do this will also allow us to test continuity between grounded and grounding paths, too. 
Any thoughts on this would be much appreciated!


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## Moonshot180 (Apr 1, 2012)

What's N-G voltage at the recep' with the copy machine not plugged in?


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## Pete m. (Nov 19, 2011)

Is the service 208Y/120? Or, is there a transformer for 120 volt loads?

Pete


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## Bad Electrician (May 20, 2014)

There better be neutral to ground voltage or you have a wiring error on the neutral.

This is Voltage Drop (VD), at the transformer the neutral is bonded to ground, the further away from this point with load on the branch circuit there will be an increase in VD between the NEUT and GND.

At the neutral to ground bond at the transformer you should have "0" volts, further away from this point the higher this voltage reading should be.

It is voltage drop in the circuit, the NEUT to GND VAC is higher at start up as the copier draws more current. 

Want to stop it run more copper less VD, Set an isolation transformer.

BUT studies have shown that copier service tech are IDIOTS or at a minimum are looking for a reason to blame equipment issues on the "ELECTRICITY". Remember he KNOWS nothing about electrical distribution except when he and his buddies discuss as a reason to blame others in lieu of solving the issue with their machines.

I had a site with 15 VAC between NEUT and GND and computers, copiers faxes and the secretaries space heaters all worked fine. This was in a 12 story building with 208/120 VAC distribution so the NEUT to GND bond was 14 floors away in the main electric room in the lower basement.

Had a SCIF loaded with sensitive electronic equipment the NEUT to GND voltage was 120 VAC, no issues until someone saw the problem and freaked out turning off all the power to the SCIF. They fed the SCIF with a motor generator and the electrician did not bond the XO, later at some time they had a short on a branch circuit grounding one phase.

We do power quality studies regularly and very seldom is the issue related to electricity, it is generally equipment issues. It ain't the grounding, lack of ground rods, loose connection, utility, harmonics or VOODOO Magic.


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## Bad Electrician (May 20, 2014)

I should add in the site with the 15 VAC we added an isolation transformer at the point of use and the NEUT to GND voltage was next to nothing, funny thing the copier issues continued, so they said the past voltage issue damaged the unit, the sold them a new copier.

The other issue we located the short and properly bonded XO.


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## Bird dog (Oct 27, 2015)

.[/quote]
We do power quality studies regularly and very seldom is the issue related to electricity, it is generally equipment issues. It ain't the grounding, lack of ground rods, loose connection, utility, harmonics or VOODOO Magic.[/quote]

Cheap equipment, the least they could do is provide/inform customer they need TVSS and or UPS. Yes, I know that won't happen. Find another copier company.


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## te12co2w (Jun 3, 2007)

I love this site. Always learning something new.


Bad Electrician said:


> There better be neutral to ground voltage or you have a wiring error on the neutral.
> 
> This is Voltage Drop (VD), at the transformer the neutral is bonded to ground, the further away from this point with load on the branch circuit there will be an increase in VD between the NEUT and GND.
> 
> ...


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## Spark Master (Jul 3, 2012)

Copy machine companies like to sell power condititors. I see these big useless bricks under many copy machines, and the client says the copier company refuses to service the machine without one.


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## emtnut (Mar 1, 2015)

Sounds like they are full of sheaths 

The unit gets the machines 'common' from the line and neutral from the power supply. The actual ground wire (grounding conductor) is a saftey in case of a short or equipment malfunction.

I've seen incoming power be the problem , but with spiking, harmonics, or just plain excessive voltage drop

You could scope it, measure actual voltages on start up and running etc ...

Then get them to replace their faulty printer :laughing:


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## macmikeman (Jan 23, 2007)

te12co2w said:


> I love this site. Always learning something new.


Me too. Today I learned this- ''studies have shown that copier service tech are IDIOTS" 


Provide reference to these studies please.


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## telsa (May 22, 2015)

It's a historical fact that the FBI and NSA had special copiers that would go into trouble mode at their beck and call.

These were placed to suit themselves:

Soviet embassies, consulates, etc.
American defense contractors, etc.

One scheme had the digitized images being photocopied automatically sent off to the FBI. 

The FBI was astounded at how many highly classified high tech documents from Silicon Valley were flying through the San Francisco consulate. 

Bugging defense contractors led the FBI to the traitors that were duplicating " Do Not Copy " top secrets to the Soviets.

They never publicised any of these successes.

Eventually traitor Robert Philip Hanssen ruined the program. 

Once the Soviets were alerted to the fact that America was seeing too much -- they bloodhounded their way to the copiers.

Part of that discovery started up when the KGB 'Resident' ( local spymaster in Soviet lingo ) thought that the service tech was just too gorgeous... and a bit slow with the tech work. She was an FBI agent -- and barely knew anything about copiers. Heh.

The KGB simply followed her back to her real desk at the FBI. That took a while. ( They had to bug her service van.)


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## Big John (May 23, 2010)

I agree with Bad Electrician: Of course there's a difference between neutral and ground, especially with a high amp draw like a commercial copier. Short of installing massively oversized conductors, it would be very difficult to eliminate that.

Since this "problem" exists all the time, I'd be real interested to know what the tech is doing to "fix it" when he services the machine once a month.

As far as "loose grounds" that's utter BS: With no current flow on the equipment ground there is nothing to change potential from one end of the circuit to the other: Even if there was a very high resistance in the ground circuit you would see the same L-G measurement.


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## Bird dog (Oct 27, 2015)

Big John said:


> I agree with Bad Electrician: Of course there's a difference between neutral and ground, especially with a high amp draw like a commercial copier. *Short of installing massively oversized conductors,* it would be very difficult to eliminate that.
> 
> Since this "problem" exists all the time, I'd be real interested to know what the tech is doing when he services the machine once a month.


Reminds me of an engineer who told me they did that somewhere. The unintended consequence was having the full xfmr fault current at the receptacle.  A UPS was the better option.


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## Big John (May 23, 2010)

Bird dog said:


> ...The unintended consequence was having the full xfmr fault current at the receptacle.


 :lol: The switch on a table lamp shorts out and 22,000 amps of fault current just vaporizes some poor secretary's desk.


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## ELECTRICK2 (Feb 21, 2015)

tersus said:


> When the copier/printer machine runs or kicks on when first plugged in, I get neutral to ground voltage of around 2-3 volts at the receptacle. The company that services the customer's machine insists that its not a problem with there equipment--apparently this machine can only tolerate a n to g voltage of less than 1 v, and for every three months or so that the voltage exceeds that, they have to come out and service it. The service company told me that in similar situations in other buildings the electrician just had to find some loose grounds and tighten them up. I've checked connections from the circuit to the panel and to the MDP and everything looks good. Here's some more information that may or may not be relevant:
> - n to g voltage when the machine isn't running stays at .5 v
> - n to g voltage at the panel when the machine is running jumps from .5 v to .8 v
> - plug the machine into another circuit fed from the same panel and you get the same result
> ...


Had a similar call but it was server equipment and UPSs that died Before I say anything else, I agree with previous posts saying techs always blame the power, but just for giggles put an amp meter around all cables going into the panel that feeds the copier. A Fluke 376 with the flex probe is what I used. On the panel we were looking at we had 7 amps. 
Things we found:
1) Hot leaves panel in question and goes back to a different panel. 
Amp reading now 4A
2) Someone installed a service entry panel as a sub panel without removing the bonding screw.
Amp reading now 1.5A
3) Several recepts with excessive ground wire in JB that was touching the neutral
Amp reading now 0A

Could this cause a copier to die? Prolly not but it was interesting.


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## RePhase277 (Feb 5, 2008)

Run a 1/0 neutral to the receptacle and that will keep the N-G voltage down...


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## Bad Electrician (May 20, 2014)

ELECTRICK2 said:


> Had a similar call but it was server equipment and UPSs that died Before I say anything else, I agree with previous posts saying techs always blame the power, but just for giggles put an amp meter around all cables going into the panel that feeds the copier. A Fluke 376 with the flex probe is what I used. On the panel we were looking at we had 7 amps.
> Things we found:
> 1) Hot leaves panel in question and goes back to a different panel.
> Amp reading now 4A
> ...


If the neutral is grounded downstream from the Neutral to ground bond you have ground current but the voltage at the load (depending on where the load is) goes down.

In the old days of CRT monitors this caused screen shake.
It will result in noise on sound systems and can also cause a certain monitors to have a moving line across the monitor.


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## tersus (Jul 3, 2012)

Pete m. said:


> Is the service 208Y/120? Or, is there a transformer for 120 volt loads?
> 
> Pete


Service is 208Y/120


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## tersus (Jul 3, 2012)

Big John said:


> I agree with Bad Electrician: Of course there's a difference between neutral and ground, especially with a high amp draw like a commercial copier. Short of installing massively oversized conductors, it would be very difficult to eliminate that.
> 
> Since this "problem" exists all the time, I'd be real interested to know what the tech is doing to "fix it" when he services the machine once a month.
> 
> As far as "loose grounds" that's utter BS: With no current flow on the equipment ground there is nothing to change potential from one end of the circuit to the other: Even if there was a very high resistance in the ground circuit you would see the same L-G measurement.


My understanding is that the tech has to replace a component in it about once every three months. I guess the machine will stop working and the tech will run a diagnostic that shows a code which means 'excessive n to g voltage'. They're saying that about three months of it is what the machine can handle before it breaks down.


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## emtnut (Mar 1, 2015)

I'd be very interested as to which 'part' they have to replace.

Also, I didn't see if you posted what size conductor you are using ?


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## emtnut (Mar 1, 2015)

Here's a very interesting article on this topic.
Kind of a long read, but worthwhile.

2 important things I got out of it for your problem is
1- Check the specs on your copier, see what the 'common mode' is, and see how that compares to what you measured from neutral to ground.
2- That many 'cheap' copiers are bonding neutral to ground on their machines. Not sure if you measured with the unit plugged in, but if you do find this problem ... Bingo - Unit is non-compliant !

http://www.smartpowersystems.com/to-bond-or-not-to-bond/


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## GrayHair (Jan 14, 2013)

te12co2w said:


> I love this site. Always learning something new.


And sometimes a different way of looking at a problem; can lead to a head-slap moment.


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