Consequences of a Separate Building Not Connected to the GES

ProjectDelta

Member
Location
Michigan
Occupation
Electrician
Hello All,

My inlaws are having an issue with sparks coming from the outlets in their garage. My brother in law is also an electrician and has been trying to troubleshoot the issue for a while. The garage electrical system had been working fine for nearly 30 years before this issue arose. The first time it happened, my brother in law noticed that the sub panel to the garage was bonded. He removed the bonding screw and separated the grounds and neutrals thinking that was the issue. However, the sparking has not gone away. I assume my my Brother checked everything else out and he now believes that the issue may be due to the garage panel not being connected to a grounding electrode or to the house's GES. I'm fairly new to the trade but am somewhat knowledgable on Grounding and Bonding after we covered it in school a few months ago.

So my question is, could the lack of a Grounding Electrode be the issue here? and even if its not the case, what are the consequences of not grounding a separate building as required by the NEC. I really want to better understand the physics of why/how potential differences occur in grounded electrical systems thus necessitating the use of electrodes.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
The lack of a grounding electrode at the garage would have nothing to do with sparks coming out of the outlets. Someone needs to open them up and check wiring and connections, along with proper voltage. Also, the panel needs to be checked for correct voltage and connections.
If no EGC was ran to the garage, which was allowed for a separate building back then, the bond should remain. If a GES is added, it would be treated just like a service since no EGC was ran.
 

ProjectDelta

Member
Location
Michigan
Occupation
Electrician
Please explain clearly and concisely exactly how, when, where and under what conditions this is happening. Have you witnessed this yourself?
Without this information there really isn't anything to go on.

-Hal
I apologize if it isn't clear, I haven't seen this happen nor have I been involved with the troubleshooting. I'm told that it happens intermittently. I was more so asking if the lack of a ground rod could cause this to happen.
The lack of a grounding electrode at the garage would have nothing to do with sparks coming out of the outlets. Someone needs to open them up and check wiring and connections, along with proper voltage. Also, the panel needs to be checked for correct voltage and connections.
If no EGC was ran to the garage, which was allowed for a separate building back then, the bond should remain. If a GES is added, it would be treated just like a service since no EGC was ran.
I had a feeling that the grounding electrode isn't the issue so I'm glad someone else can confirm. I'm confident that my brother in law has checked the connections and voltage. I don't know if an EGC was run with the feeder. I see my brother in law tomorrow so I'll ask him more about it then and will post any new information I receive.

Thanks for the responses. Will update soon.
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
Without a clear explanation of what is “sparking”, it would be tough to diagnose. If the sparking is when they plug certain things in, I would venture a guess it is a high resistance fault somewhere, possibly a circuit at the house faulting to ground through something like a buried metal water line. (Ungrounded water heater or other water connected appliance). The current is returning through the frame of something at the garage, hence the arc when plugged in. A good test would be checking for voltage from the garage panel neutral and garage panel equipment ground to an isolated point such as a metal stake driven into the ground, or a metal post in the concrete slab just as a starting point.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I would start with the panel. Make sure everything is code compliant by determining how many conductors are in the feeder and possibly reinstalling the bonding screw. Then add a GES as required.
 

retirede

Senior Member
Location
Illinois
I would start with the panel. Make sure everything is code compliant by determining how many conductors are in the feeder and possibly reinstalling the bonding screw. Then add a GES as required.

Excellent advice, but I don’t see how that could be related to sparking at any outlet.
 

benmin2012

Member
Location
Saco Maine
Some loads will cause sparking when plugged in or unplugged, which is normal.

That's usually the case when I have the sparks coming from the outlet troubleshooting call. fridges, freezers, a vacuum that is in the on position when plugged in I've seen do that
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Sparks indicate current crossing a gap.

If the current that is sparking is normal house power current, then grounding electrodes have nothing to do with it.

Sparking could be a loose connection on the circuit conductors (splices or at the receptacle screws), or it could be at the receptacle contacts (these are supposed to separate, so sparks can happen normally when a load is (dis)connected, or the contact springs could be weak). If there is a ground fault then current could be flowing in the EGC with sparking.

I could imagine the possibility of the grounding electrodes being related to sparking, but this would require some source of current relative to the ground, static, lightning, high power radio, etc. There is a saying: if you hear hoofbeats think horses not zebras. All of the situations where grounding electrodes could possibly be related to receptacles sparking are zebras.

Jon
 

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
Most times I've witnessed this effect was related to loads being applied via a receptacle or a switch that would have a visible arc, in those instances it was almost always related to the switch or receptacle beginning to fail. Changing switch or receptacle out fixed the issues. Even then, depending on live loads present as a plug is inserted, or the way it is inserted, even a good receptacle may produce an arc.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Bottom line. It is highly unlikely that the absence of s grounding electrode at the garage has anything to do with the "sparking".

It could be that a load is on when unplugged. That can give you a small spark.

Could also be a wire that is intermittently open, especially a neutral.
 

sreeb

New User
Location
socal
Occupation
engineer
Can you confirm the the garage has a 4 wire connection with separate ground and neutral to the house?
 
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