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Terence McCann

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I don't get into the 'why' of it.

The ____ does not have a grounded receptacle near it. Grounded receptacles are needed for some appliances, including this one. You should have a qualified electrician install the appropriate wiring and receptacle(s) as needed.

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Regarding why grounded outlets are necessary on refrigerators, automatic garage door openers etc.

Tanks.

Grounded receptacles are necessary on these appliances because the appliance manufacturers require it.

- Jim Katen, Oregon

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I get asked why all the time. I have always *thought* that when the windings of an electric motor start to break down that current can leak to the casing. This is how folks get zapped when they touch the refrigerator and the sink for example. If this holds true then I'm looking for a polished way to put this in a report.

If this isn't true then I have a bigger problem.

On a side - when I recommend a repair I try to give a reason that folks can relate to besides "the code states".

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I get asked why all the time. I have always *thought* that when the windings of an electric motor start to break down that current can leak to the casing. This is how folks get zapped when they touch the refrigerator and the sink for example. If this holds true then I'm looking for a polished way to put this in a report.

If this isn't true then I have a bigger problem.

On a side - when I recommend a repair I try to give a reason that folks can relate to besides "the code states".

I just tell them pretty much what Jim stated. The manufacturers require it. That usually ends the discussion on that subject.

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Terry, I just say something like, "It's inherently unsafe to operate the fridge/microwave/fill-in-the-blank when it isn't plugged into a grounded outlet because someone could receive a shock or even be electrocuted.

I'm not certain an average person is going to understand that an electrocution risk exists just because a manufacturer says an appliance has to be plugged into a grounded outlet.

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I get asked why all the time. I have always *thought* that when the windings of an electric motor start to break down that current can leak to the casing. This is how folks get zapped when they touch the refrigerator and the sink for example. If this holds true then I'm looking for a polished way to put this in a report. . . .

That's my understanding as well. Any water that might have found its way into the coils when they were charged will acidify the refrigerant. If that happens, the acidic mixture will slowly break down the insulation on the windings and cause them to leak current to the casing. That scenario used to be quite common and its one of the reasons why people still think that refrigerators will trip GFCIs.

How about, "Refrigerators sometimes leak electrical current as they age. If such a refrigerator is plugged into an ungrounded receptacle, it could shock someone."

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C'mon Jim, The exterior metal housings of these appliances are bonded to the grounding conductor. If they are ungrounded and there is a ground fault, the housing of the appliance is now hot. The metal housing of any appliance or tool that has a 3-prong plug is involved in the proper grounding of that tool or appliance and should be plugged into a grounded receptacle.

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It's better that the path of fault currents from a defective electrical appliance reach the earth by way of a deliberate electrical grounding conductor than by human contact.

Marc

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Is it reasonable to simply say....

"There's ungrounded outlets @ XYZ; they are a shock or electrocution hazard."

That's it. I've usually got a pic of the outlets with an arrow pointing at them.

I've got a single recommendation @ the front of my report that says, in effect.....

"If something is listed in this report as a defect, that means you should have an appropriate contractor fix it. If you aren't sure about the repair, or what contractor is appropriate, call my office to discuss."

I think I've gotten a couple calls to discuss in 2 years, but that's about it.

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I add that if the manufacturer requires that the device/appliance be powered from a grounded receptacle, and this requirement is not met, the manufacturer may not honor their warranty. This is not just a theoretical issue, some manufacturers of computers and peripherals (ex: Dell) specifically instruct their service personal to be alert for such conditions when they are performing on-site service.

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It's better that the path of fault currents from a defective electrical appliance reach the earth by way of a deliberate electrical grounding conductor than by human contact.

Marc

The earth is a poor conductor of electricity. The current is not going to earth.

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"I used to use an adapter to plug my three prong refrigerator into a two slot receptacle. It worked great for 14 years. Somewhere around the 15th year something went wrong- if you touched the frig, you were shocked. If you touched it again, it was re-volting. This isn't the best or safest method to determine the useful life of an appliance and it's exactly why manufacturers install three prong plugs in the first place- to ensure that you use a grounded receptacle."

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The metal ground from the motor, cabinet, etc. of an appliance through the cord, receptacle, cable, distribution panel and into the ground offers much less resistance to current than if the path is through the cabinet, through your body, and then to ground through whatever else you are touching, even a grounded plumbing fixture. Electricity takes the path of least resistance. Does not matter a bit whether the earth is a good conductor or not, that resistance is overcome by the 8' ground rod, 10' of METAL water pipe and/or Ufer foundation rebar grounding system.

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Electricity takes the path of least resistance. Does not matter a bit whether the earth is a good conductor or not, that resistance is overcome by the 8' ground rod, 10' of METAL water pipe and/or Ufer foundation rebar grounding system.

Electricity doesn't choose just the best path to ground- it chooses every path.

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Electricity takes the path of least resistance. Does not matter a bit whether the earth is a good conductor or not, that resistance is overcome by the 8' ground rod, 10' of METAL water pipe and/or Ufer foundation rebar grounding system.

Electricity doesn't choose just the best path to ground- it chooses every path.

But it is still the one, with the least resistance, that gets chosen correct?

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If there's a path that will carry a milliamp, then it'll meter at a milliamp- if it only chose the best path, it'd be perfectly safe to touch the line 1 terminal on a running motor. Instead, if you touched the line 1 terminal on a motor you'd be buzzed and the motor would keep on running.

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All parallel paths are taken at the same time. The division of the current among the various paths depends on how well each individual path conducts. Some may be too small to be significant. A path consisting of copper wire will carry a much bigger share of the current than a parallel path completed by human contact. Eliminate that copper path and the human will feel a much bigger share of the current.

Marc

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If there's a path that will carry a milliamp, then it'll meter at a milliamp- if it only chose the best path, it'd be perfectly safe to touch the line 1 terminal on a running motor. Instead, if you touched the line 1 terminal on a motor you'd be buzzed and the motor would keep on running.

True, if you were a conduit to ground - however I'm not sure that senerio fits to what is being discussed. If there is a ground fault on a refrigerator, and the refrigerator is plugged into a properly grounded outlet, then the path that the current would chose would be through the grounded outlet and not through your body (given the choice).

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If there's a path that will carry a milliamp, then it'll meter at a milliamp- if it only chose the best path, it'd be perfectly safe to touch the line 1 terminal on a running motor. Instead, if you touched the line 1 terminal on a motor you'd be buzzed and the motor would keep on running.

True, if you were a conduit to ground - however I'm not sure that senerio fits to what is being discussed. If there is a ground fault on a refrigerator, and the refrigerator is plugged into a properly grounded outlet, then the path that the current would chose would be through the grounded outlet and not through your body (given the choice).

For all practical purposes, you're correct. The current through the path that was completed by human contact would most likely be insignificant assuming the human's skin wasn't pierced and is dry.

Marc

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The metal ground from the motor, cabinet, etc. of an appliance through the cord, receptacle, cable, distribution panel and into the ground offers much less resistance to current than if the path is through the cabinet, through your body, and then to ground through whatever else you are touching, even a grounded plumbing fixture. Electricity takes the path of least resistance. Does not matter a bit whether the earth is a good conductor or not, that resistance is overcome by the 8' ground rod, 10' of METAL water pipe and/or Ufer foundation rebar grounding system.

Do you really think a ground rod or water line, Ufer etc is necessary to have a properly wired receptacle?

Ground rods etc have nothing to do with the third prong.

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The metal ground from the motor, cabinet, etc. of an appliance through the cord, receptacle, cable, distribution panel and into the ground offers much less resistance to current than if the path is through the cabinet, through your body, and then to ground through whatever else you are touching, even a grounded plumbing fixture. Electricity takes the path of least resistance. Does not matter a bit whether the earth is a good conductor or not, that resistance is overcome by the 8' ground rod, 10' of METAL water pipe and/or Ufer foundation rebar grounding system.

Do you really think a ground rod or water line, Ufer etc is necessary to have a properly wired receptacle?

Ground rods etc have nothing to do with the third prong.

You got me thinking about it now Jim. The third prong gives the current an alternate path (if needed). The path is back the the service equipment where the ground and neutral is bonded, hence, sending the current back to the source it came from (power company for instance).

Is that it?

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