equipment in garage gives me a tingle

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  #1  
Old 08-31-15, 05:49 PM
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equipment in garage gives me a tingle

Greetings,

Hoping someone can point me in a direction. The electrical in my garage is kind of a mess. I bought the house a little under a year ago. I've noticed that when using certain things in the garage such as my air compressor or my shop light, I'll get a tingle/buzz if I touch a metal portion of the tool (such as the handle for the air compressor.) This is obviously not good! I'm hoping someone with more electrical experience can shed some light on what's happening. I'm not afraid of electrical, I'm just more experienced with automotive electrical than I am house.

Thanks

EDIT: I forgot to add that I have one of those receptacle testers that light up when you plug it in. It tells me everything looks ok. The particular plug in question is a 2 prong that the previous owner put a 3 prong adapter in and screwed the ground piece into the box. However, I've had the same thing happen from other 3 prong receptacles in the garage.
 
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Old 08-31-15, 05:57 PM
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It would appear that someone installed a three prong receptacle where a ground may not exist. It is very possible that the neutral was used a ground wire which is not correct and that tester would show ok.

You will need to remove the receptacles and visually inspect inside the box for a ground wire.
Is the wiring in the garage exposed ?
 
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Old 08-31-15, 06:03 PM
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the wiring is not exposed, There's drywall in the garage. I wondered if it had to do with grounds.

Can you explain a little of what may be going on?


I appreciate the quick response
 
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Old 08-31-15, 06:10 PM
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The wiring may be older and not have a ground wire. If that is the case then the three prong receptacles should not be installed there. You could use two prong receptacles or upgrade the receptacles to GFI type which is what code now requires in a garage.

Here is a problem though..... if you are getting a tingle from certain equipment and you plug it into a GFI receptacle.... the GFI will trip. You may have to look at the equipment you are using and see if it has a problem.
 
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Old 08-31-15, 06:13 PM
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GFI is required in a garage at this point by code anyway? Would installing GFIs help with my "tickle" issue?

I'm just thinking if GFIs are code AND will address the issue I'm having, there's no reason not to replace the receptacles.
 
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Old 08-31-15, 08:25 PM
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I am suspecting a bootleg ground.

A gfi is a worthwhile upgrade for your safety. They would be required under the latest codes or if your replaced a receptacle.
 
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Old 08-31-15, 08:33 PM
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why does the funky ground situation cause me to get zipped a little bit? If the GFI will resolve the issue AND is up to code, I see no reason not to do the upgrade (other than cost of course, but houses cost money).
 
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Old 08-31-15, 09:00 PM
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I agree with the others that a "bootleg" equipment ground is likely. The reason why you would get a tingle is that you would have a parallel path for the neutral on any grounded object.

A bootleg ground is formed when the equipment ground (green) screw is connected to the neutral (white) screw on the receptacle. Some people, in their ignorance of HOW the equipment grounding conductor provides a measure of safety, erroneously think that because the equipment grounding conductor is connected (bonded) to the neutral conductor in the service panel it may also be connected to neutral anywhere else in the system.
 
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Old 08-31-15, 09:13 PM
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I'm more familiar with DC, but thinking flow, are you basically saying the power is flowing from hot, through the load, and into the neutral, but because of the bootleg it also feeds into the ground?
 
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Old 08-31-15, 09:23 PM
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but because of the bootleg it also feeds into the ground?
Yes, and through you to the ground when you touch the metal of the equipment.
 
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Old 08-31-15, 09:35 PM
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Thx guys that helps me understand better what's happening. So will a GFI help prevent that from happening then? Does it just trip or is there something else going on?
 
  #12  
Old 08-31-15, 10:36 PM
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A GFCI (Ground Fault Current Interrupter) compares the current on both the "hot" and "neutral" conductors and if there is an imbalance of more than six milliamperes it will "trip" and remove the power from the load. A GFCI is for personnel safety and does NOT replace the equipment grounding conductor which is for system safety.

As an example imagine a metal-cased drill motor. With no "faults" the equipment grounding conductor (the green wire) plays no part in the operation of the drill. Power comes in on the black wire, turns the motor and returns to the SOURCE over the white wire. (It is quite a bit more involved but this simple explanation shows the action.)

Now let us create a bootleg ground at the receptacle where this tool is plugged in by connecting a jumper wire from the green screw to the white wire. Now the returning current has TWO paths back to the source, the primary path is still through the white wire but a portion of the current will now travel from the white wire of the tool to the green wire of the tool, back to the metal case of the tool, through your hand and body to the earth where it travels through the earth back to the source through the ground rod that is solidly connected to the white wire in the serviced panel.

Now here is where a lot of people make a serious mistake. They correctly assume that the path through the body and the earth has a much higher resistance than the path through the wiring and then make the mistake, sometimes a deadly mistake, in assuming that electricity follows the path of least resistance. It does not. ELECTRICITY FOLLOWS ALL PATHS BACK TO THE SOURCE. The resistance, or more properly, the impedance (AC resistance) of the return path determines how much current flows on each path. Remember, it only takes 30 milliamperes, that's 0.030 amperes, to stop your heart. That current that is following the parallel path through the bootleg ground CAN KILL YOU if it travels across your heart.

Now let us consider a "fault" where the winding of the drill motor comes into contact with the metal case. Without a proper equipment ground you will have a path from the source, through the drill's trigger switch, through a portion of the motor's winding and then to the case of the drill. Your hand/body provides a path to the earth and the earth provides a path back to the source. The current flow through this alternate (fault) path is dependent upon the impedance of the path but under certain conditions could be enough to kill you.

However, with an intact equipment grounding conductor (the green wire) from the metal case of the drill all the way back to the serviced panel what will happen is the majority of the current flow will follow this low impedance path and since this path is what is commonly known as a "short" (really, a short circuit) it will cause the branch circuit breaker to trip because of excessive current flow.

So, your next task is to check each and every connection in your garage to ensure that there are NO connections between the white wire and any grounded item OR to any green terminal. Also, you need to ensure that ALL of the green equipment grounding terminals are connected to a proper equipment grounding conductor.
 
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Old 09-01-15, 09:22 AM
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Thanks for taking the time to write that detailed response Furd, that is really good information.

Any idea why I get that buzz from the receptacle using the 2 to 3 adapter? Just curious, I'm sure it's more of exactly what you said. Perhaps the box is "grounded" on a bootleg or some sort, so the Previous Owner having the grounding tab on the adapter screwed in results in the same thing you described above.

Worse case scenario, if it's only 2 conductor wiring instead of 3, what are my options?

Thanks again
 
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Old 09-01-15, 09:25 AM
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Worse case scenario, if it's only 2 conductor wiring instead of 3, what are my options?
Right back where you started. Install GFI receptacles as a ground is not required for protection.
 
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Old 09-01-15, 11:45 AM
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Well that's simple enough then. Thanks a lot you guys.

Mind if I pick your brains a bit more on this? I'm just trying to learn more about what is actually going on. Why does the GFI get rid of the need for a ground conductor? Is it because it will trip if it senses a fault? It would fix the issues I'm having because it's isolating the ground from what we assume is the neutral (bootleg) connection, right?
 
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Old 09-01-15, 12:40 PM
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Why does the GFI get rid of the need for a ground conductor?
It doesn't. It just increases personal safety.
Is it because it will trip if it senses a fault?
No because it senses a difference of more than 6ma between hot and neutral.
t would fix the issues I'm having
No. You need to check to see if you have a bootleg ground and fix it first. Note: You need only one GFCI, the first receptacle, if you feed the rest from the load side. The non GFCI receptacles need to be labeled GFCI Potected-No Ground with labels inclosed with the GFCI.
 
  #17  
Old 09-01-15, 12:52 PM
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Thx Ray. So that goes back to my question about if I have wiring that is only 2 conductor (hot and neutral) vs 3 wire (hot neutral ground). How can I have a ground with only 2 wires? I don't think I can.
 
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Old 09-01-15, 12:58 PM
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You're correct. You can't have an equipment ground on a two wire circuit. The GFCI makes that situation safer by cutting off power when it detects a fault (which it assumes is a shock), but it does not create a ground where one does not previously exist.
 
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Old 09-01-15, 01:03 PM
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Thanks ibpooks. So if I wanted to do it "right" and have an equipment ground, I'd need to rewire the garage?

I'll be honest, the wiring is a mess. The garage is fed by a plug in the basement.. It's super not good. If I want to cut power to the garage, I can just "pull the plug" and that's that.
 
  #20  
Old 09-01-15, 01:47 PM
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Yes either rewire the garage or run a separate ground wire to each receptacle, which is allowed by code for a retrofit situation. However running a single ground wire isn't really much different than just running all new cable in terms of labor or price.

I didn't catch if this was an attached or detached garage and the age, but a rewire would probably mean trenching and pulling new conductors from the house too. Older outbuildings were often installed without a ground.

The "plug" connection is actually easy to do a major safety upgrade just by replacing that receptacle with a GFCI receptacle. $12 and you'll improve the safety out there by 1000% It's still not the "right" way to do it, but it will improve the most dangerous situation.
 
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Old 09-01-15, 02:21 PM
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Thx ibpooks. I'm going to do GFCI regardless, since according to an earlier post that's code now in a garage (not to mention the added safety). It's a detached garage, but it's not far from the house. There wouldn't be more than 10ft of trenching I'd imagine.

[off topic]
I have a lot of electrical work to fix. I have an old pushomatic breaker box I want to have replaced. I'm hoping to get the garage on its own breaker at that point and plan to upgrade the feed to the garage at that point.

While we're talking plans to fix the garage, what I'd REALLY like to do is have 220 available out there. It seems that when i'm fixing the panel and the feed to the garage, that would be a great time to do the 220 feed.

Anyway, back on topic, it seems that my best first step is to look for the bootleg grounds, and replace the receptacles with GFCIs. That'll add a lot more safety to the situation, and when I get around to fixing the wiring in the garage, I can reuse the GFCIs.
 
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Old 09-01-15, 02:30 PM
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what I'd REALLY like to do is have 220 available out there.
You can't because your house has 240v.
Anyway, back on topic, it seems that my best first step is to look for the bootleg grounds,
Yes.
and replace the receptacles with GFCIs.
No. Only the receptacle it is plugged into should have a GFCI. This is especially important because the wiring method from there to the detached garage likely does not meet code.
when I get around to fixing the wiring in the garage, I can reuse the GFCIs.
Only one, maybe two GFCIs will be needed when you redo the garage. As I previously wrote:
You need only one GFCI, the first receptacle, if you feed the rest from the load side.
As Ibpooks previously wrote:
The "plug" connection is actually easy to do a major safety upgrade just by replacing that receptacle with a GFCI receptacle. $12 and you'll improve the safety out there by 1000%
 
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Old 09-01-15, 02:43 PM
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Ray:
"No. Only the receptacle it is plugged into should have a GFCI. This is especially important because the wiring method from there to the detached garage likely does not meet code."

you're saying the receptacle the garage is plugged into? inside the house? Or are you saying the first receptacle in the garage (or both?)

Thanks, sorry if that's a goofy question.
 
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Old 09-01-15, 03:52 PM
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inside the house? Or are you saying the first receptacle in the garage (or both?)
Initial replies were given without knowledge of the receptacle and plug in the house. Given there is a receptacle in the house that is the only place you need a GFCI.
 
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Old 09-01-15, 04:02 PM
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Thx Ray. That's why I wanted to clarify, since i obviously didn't tell the whole story at first. Sorry about that.

So, Look for bootleg grounds, replace the receptacle feeding the garage with a GFCI, and go from there. That seems to be the initial game plan.
 
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Old 09-01-15, 04:06 PM
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Yes that is a good first step. Could you post a picture of the cord to the garage in the house giving a good view of the cord and receptacle.
 
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Old 09-01-15, 04:14 PM
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Ray, I sure will as soon as I can. I can't even remember exactly how it is. I just remember a plug in the basement in the "ceiling" (the basement is unfinished). It's definitely not anywhere near up to code. I seemed more alarmed by it than the home inspectors, but that's also not surprising. It's just one of many repairs this house needs. At least the land is nice
 
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Old 09-01-15, 07:51 PM
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Hey another goofy question. What's a better bad situation: Boot leg ground or no equipment ground?
 
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Old 09-01-15, 08:06 PM
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Boot leg ground or no equipment ground?
No contest, bootleg ground. It is the one most likely to kill you. No EGC is under normal circumstances not hazardous.
 
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Old 09-01-15, 08:12 PM
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No contest, bootleg ground. It is the one most likely to kill you. No EGC is under normal circumstances not hazardous.
Whelp, that's all I needed then. I'll get those pictures as soon as I can, and I'll start looking for bootleg grounds. It's stupid that someone would put in the extra work to create a more dangerous situation.
 
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Old 09-01-15, 09:15 PM
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A bootleg ground will fool a 3 light tester so it looks grounded.
 
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Old 09-01-15, 09:21 PM
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A bootleg ground will fool a 3 light tester so it looks grounded.
I figured I would just pull the receptacles and look for a bootleg in each one. Is there a better option?
 
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Old 09-01-15, 10:03 PM
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Yes that is the best option. It will also allow you to check for any other problems such as deteriorated insulation on the wires or loose connections.
 
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Old 09-02-15, 12:41 AM
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As PC noted the bootleg ground will fool the average testing device but I think the primary reason is that people simply do not understand the way the separate equipment grounding conductor works. They see that both the neutral and the equipment ground are connected together in the service (main) electrical panel and then ASSume there is no difference and that merely connecting the equipment grounding (green) terminal to the neutral serves the same purpose. As I pointed out in my previous post this is an erroneous assumption.

Even some "professional" electricians are completely baffled by the concept of the equipment grounding conductor and I have even seen forums where a supposed professional stated that connecting the equipment grounding terminal to the neutral was an acceptable method of providing an equipment ground. Fortunately, others are quick to shoot this idea down but the idea refuses to die.
 
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Old 09-02-15, 06:14 AM
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the only variable to the bootleg ground theory is that the plug i've been using is a 2 prong with a 3 prong adapter w/ the ground loop screwed in with the face plate screw.

Thinking back to the times I have had this issue happen, it has always been with something that uses an equipment ground, never something that is insulated enough to not need the 3rd prong. That makes sense, just providing as much evidence as I can.

So I wonder if voltage is leaking up the little ground strap bit on the adapter into the tools I'm using, giving the feeling that makes you feel alive.

I know there's other issues because the same thing has happened from a 3 prong adapter, so boot leg ground search is of course still on. That 2 prong w/ the adapter is just 1 additional variable.

Thanks again for letting me get the ideas out and bouncing around those of you with more experience. I really like learning how this stuff works.
 
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Old 09-02-15, 09:43 AM
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that the plug i've been using is a 2 prong with a 3 prong adapter w/ the ground loop screwed in with the face plate screw.
A ground adapter can't be used unless the system has a metal box and the box is properly grounded. You don't have that so an adapter can't be used.

It would take about the sane amount of time to abandon what is there and run a correct supply as it would to troubleshoot what you have. Given there is no way to fully correct what you have the only good safe option is to stop trying to half-a** fix it and just do it right.

If you want to do it right post back for the bare minimum how to.
 
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Old 09-02-15, 10:24 AM
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Hi Ray,

My intentions are to do it properly. I'm trying to fix the half-assery of the previous owner of the house. I inherited this nest of issues when I bought the home. I still need to be able to use some of the power in the garage while it's being repaired, and I likely have some dependencies to address (such as the breaker box) so this is the planning stage.

In addition to fixing the problem, I want to better understand WHAT is happening and WHY it's happening. That is part of why I've been asking the number of follow up questions I have. I'm sorry if you find these to be rudimentary, my intention is not to cause frustration.
 
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Old 09-02-15, 11:23 AM
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We are not frustrated and welcome your questions but we would also like to resolve your problems in the safest way possible. At the very least change the receptacle in the basement to GFCI and look for a bootleg ground.
 
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Old 09-02-15, 11:43 AM
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Hi Ray,

I just wanted to be sure I wasn't wearing on a nerve. Those 2 things are definitely the first two items on my list to begin addressing the electrical in the garage
 
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Old 11-14-15, 04:14 PM
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Here's the plug that feeds the garage. If you look closely there appears to be a ground wire that is not hooked to anything and is instead wrapped back onto the cable. Any reason I couldn't use a junction box and wire this more properly?
 
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