Electrical Shocks

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  #1  
Old 08-19-06, 09:08 AM
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Angry Electrical Shocks

Hi All,

I have an outlet in our living room which I think has a short some where. The home was built in 94, and the outlet in particular has the three hole connection.
I our entertainment area we have a tv, stereo receiver and sat box connected in this area.
All equipment has the two prong plugs right now with the exception of the power strip they all plug in too, its a three prong plug.

I noticed that if I use equipment with the grounded third plug on any of the two pieces of equipment I will get a shock when I touch the outer casing. I have taken my volt meter and have actually measured touching the outside cases of the sat box and the stereo reciever with the meter probes and have measured up too 76.7 volts A/C. (Again this only happens if one of the two uses the third grounded plug)

if I use two connections with the grounded third plug at the same time, well you know what happens something frys.

I have used one of those small yellow plug in connector testers with lights, which tell you if you have an open or ground missing. This checks out ok, but I know something it not right here otherwise I would not get some shocks.

I dont know where two begin here so if one of your knowledgeble members could provide some directions I would appreciate it.

Thanks

Proton
 

Last edited by proton; 08-19-06 at 01:00 PM.
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  #2  
Old 08-19-06, 09:38 AM
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I am having dissiculty understanding a point or two.

You state :
All equipment has the two prong plugs right now with the exception of the power strip they all plug in too, its a three prong plug.

at one point, then you go on to post:
noticed that if I use equipment with the grounded third plug on any of the two pieces of equipment I will get a shock when I touch the outer casing.

can you clarify that last statement? How do you "use equip with the grounded 3rd plug" "on any of the 2 pieces of equipment"?

Aslo: have you tried using any other recep in an attempt to figure this out.
The 110 you are experiencing can be lethal is there is any current available. Use extreme caution. Actually I believe most here would recommend an elelctrician be called because of the serious nature involved. Are you capable of dealing with this situation safely? (training or experience to be so?)
 
  #3  
Old 08-19-06, 12:59 PM
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Originally Posted by nap
can you clarify that last statement? How do you "use equip with the grounded 3rd plug" "on any of the 2 pieces of equipment"?
Sorry,I will try to clarify.
The power strip has the three hole recepticles on it, six to be exact and connects via a grounded plug.(three prong) Which connects to a tree prong recepticle.

I am only using connections to this strip that donot use the ground prong. So ground connections on this multi outlet strip are not bein g used.

I checked the recepticles with my volt meter and ground to line reads 120 volts ac and ground to neutrel reads .002 volts ac.

Connecting my meter between the unused ground hole on the mulit strip outlet to the outer caseing of my sat reciever reads 77.6 vac.

I suspect there is a floating ground here or a shorted one somewhere in this circuit.

Hope this clarifies things up a bit, sorry.
 
  #4  
Old 08-19-06, 02:24 PM
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I missed how the three prong rec that the whole mess plugs into checked out. is it ok? Are you sure you have a good ground here?
 
  #5  
Old 08-19-06, 02:29 PM
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Taking readings between the outlet and the case of some equipment that does not have a full size ground wire is the same as testing between the rec and your budda statue or pictue of george bush. Meaningless.

Tells us the readings from hot to ground, and from hot to neutral and .. well we got that one and it looked good.
 
  #6  
Old 08-19-06, 02:42 PM
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"I checked the recepticles with my volt meter and ground to line reads 120 volts ac and ground to neutrel reads .002 volts ac. "

I would write the .002 off to a probable anomaly. If you are using a DMM, these meters often read a small amount of voltage due to the high impedance of the meter and their sensitivity. This reading should actually be 0. .002 doesn't sound like a problem. Did you take a neut to hot reading? It should be 120 (or your actual line voltage)

"Connecting my meter between the unused ground hole on the mulit strip outlet to the outer caseing of my sat reciever reads 77.6 vac." That shows there is a probable short to ground within your reciever.

That is the problem of not having an equipment grounding conductor and a metal case. If a piece of metal becomes energized and it has no connection to ground, it will do nothing until something (or somebody) that touches it and is grounded. They will be shocked.



. Is the power strip a surge supressor as well?

If so, try a different one. Also try plugging the sat reciever directly into the wall without utilizing the strip and check ground to case then. Plug each of the appliances directly into a wall recep and check the situation again. This will either determine which (if any) may have a short or point to the strip as some sort of problem.

Just be damn careful with the voltage. It takes much less to kill than most people realize.
 
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Old 08-19-06, 02:47 PM
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Taking readings between the outlet and the case of some equipment that does not have a full size ground wire is the same as testing between the rec and your budda statue or pictue of george bush. Meaningless.

I have to disagree with you here jwhite. If there is a short in the reciever and there is no ground to allow for a fault current to flow, it will not trip the breaker but it will set up a potentially letahl situation. If there is line voltage to the case of the reciever, you would most definatley get some reading to house ground and it does have meaning. The lower voltage readings could be due to resistance anywhere in the circuit being read.
 
  #8  
Old 08-19-06, 02:51 PM
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Originally Posted by nap
jwhite


Taking readings between the outlet and the case of some equipment that does not have a full size ground wire is the same as testing between the rec and your budda statue or pictue of george bush. Meaningless.

I have to disagree with you here jwhite. If there is a short in the reciever and there is no ground to allow for a fault current to flow, it will not trip the breaker but it will set up a potentially letahl situation. If there is line voltage to the case of the reciever, you would most definatley get some reading to house ground and it does have meaning. The lower voltage readings could be due to resistance anywhere in the circuit being read.
any of those conditions could exhist. without a common reference point to ground. the meter readings will tell you nothing about them.
 
  #9  
Old 08-19-06, 02:56 PM
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Hey guys I did a real quick read of this and I'm wondering what you guys think of the possibility that he has had a grounding receptacle installed on 2 wire without ground (ungrounded wiring) and then someone has put on a bootleg ground. Thats why his tester is fooled by the connection of the neutral to the ground screw. Since this would put neutral current on his metal cases that might be why he is getting shocked. Might be off base but read this real quick so may have missed something.

Disregard I just saw where he is on using two prong plugs in the power strip.
 
  #10  
Old 08-19-06, 02:57 PM
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Originally Posted by jwhite
Taking readings between the outlet and the case of some equipment that does not have a full size ground wire is the same as testing between the rec and your budda statue or pictue of george bush. Meaningless.

Tells us the readings from hot to ground, and from hot to neutral and .. well we got that one and it looked good.

I checked the recepticles with my volt meter and ground to line (right side of outlet)reads 120 volts ac and ground to neutrel (left side of outlet)reads .002 volts ac.

Hope this helps clarify somethings
 
  #11  
Old 08-19-06, 03:05 PM
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any of those conditions could exhist. without a common reference point to ground. the meter readings will tell you nothing about them.
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We may be misunderstanding each other but if house voltage is connected to the case in any way, there is a ground reference and the OP is utilizing it to take this particular reading. The ground terminal of the power strip(that is plugged into the wall) (or actually since I suggested pluggin directly into a wall recep, he is definately dealing with the correct reference if the house voltage is shorted to the case)is the ground reference for the house voltage.
 
  #12  
Old 08-19-06, 03:48 PM
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he said two prong outlet on the appliance. there is no reference to ground.
 
  #13  
Old 08-19-06, 04:27 PM
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It makes no difference with the two blade. The voltage is not produced by the appliance, it comes from the house. The ground reference would be between the house voltage (which may be on the appliance case) and the house ground. (unless there is a transformer involved causing this problem.)


The reference is from the house voltage to house ground. Unless there is a transformer inside the appliance that is the cause of the voltage on the case, the only voltage there is is from the house, therefore house ground is the reference point whether there is an egc to the appliance or not. (trust me, I have a friend that saw the other side for awhile from just such an experience)

The fact that it is only a two blade actually causes a safety issue since the case being energized will not cause the breaker to fault trip since there is no effective ground path UNTIL the op touches the case while being grounded. The it ma be too late to worry about the ground.


The problem I have that may be my point of confusion is from the OP's first post:

"I noticed that if I use equipment with the grounded third plug on any of the two pieces of equipment I will get a shock when I touch the outer casing. I have taken my volt meter and have actually measured touching the outside cases of the sat box and the stereo reciever with the meter probes and have measured up too 76.7 volts A/C. (Again this only happens if one of the two uses the third grounded plug)"

I do not completely understand what he is referring to with the "if I use equip with the grounded third plug on any of the two pieces of equip" part.

Is he speaking of an aux recep on the reciever that has a ground recep included that he is plugging in another appliance? If so, there should be a 3 wire to the first appliance to start with. I can think of some obscure situations where this may lead to such a problem.

If he would do as I suggested and give some info back, there is obviously enough experience and knowledge here to more than likely remedy this situation but the OP seems to have taken a dinner break.






.
 
  #14  
Old 08-19-06, 08:20 PM
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a longshot

There's are questions that still need answers. How long have you lived at the house. Has the receptacle been working before or is this the first time you noticed? Has anyone attempted to do any electrical work in that particular area or anywhere in there for that matter?
This may be a longshot but it may be worth a try. You would need to turn off the circuit breaker that energizes that area that you are having the trouble. Once you have confirmed the receptacle is de-energized, remove the cover plate and pull out your receptacle and wires in that box. Do you see anything like a white wire not connected or cut? Do you see anything with a burn mark? Don't stop there, check all your switches and receptacles and see if you find anything unusual. I'll give you an example, I moved in this house that I just bought and was switching out ceiling fans, I usually just turn the switch off to exchange except this time when I touched the ground wire, it hit me good. When I removed the switch that controls the ceiling fan, I have found that someone had the broken the neutral and had put it on the switch. It seems that when the neutal becomes open that somewhere it seems to go through the ground for the return. The switch should have 2 black wires connected to it. Like I said, it may be a longshot but you got a little time you could check some things out. If this is over your head then by all means hire a qualified electrician to service your problem.
 
  #15  
Old 08-19-06, 08:29 PM
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Originally Posted by proton
Hi All,

I have an outlet in our living room which I think has a short some where. The home was built in 94, and the outlet in particular has the three hole connection.
I our entertainment area we have a tv, stereo receiver and sat box connected in this area.
All equipment has the two prong plugs right now with the exception of the power strip they all plug in too, its a three prong plug.

I noticed that if I use equipment with the grounded third plug on any of the two pieces of equipment I will get a shock when I touch the outer casing. I have taken my volt meter and have actually measured touching the outside cases of the sat box and the stereo reciever with the meter probes and have measured up too 76.7 volts A/C. (Again this only happens if one of the two uses the third grounded plug)

if I use two connections with the grounded third plug at the same time, well you know what happens something frys.

I have used one of those small yellow plug in connector testers with lights, which tell you if you have an open or ground missing. This checks out ok, but I know something it not right here otherwise I would not get some shocks.

I dont know where two begin here so if one of your knowledgeble members could provide some directions I would appreciate it.

Thanks

Proton
I would think some of the outlets are wired incorrectly but dont rule out problems with the eqipment, extension cords or power strips. Once you verify the outlets are correct plug in the power stips and extension cords and verify them also. Once I bumped 2 test equipment carts together and there was quite and arc before the breaker tripped. I found that one of the varts had a miswired power strip on it.
 
  #16  
Old 08-20-06, 03:44 AM
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Two pronged appliances have an oversized prong that will only allow the plug to plug in with a certain 'polarity', for lack of a better term. What if the wall plug was wired backwards?

That's the first thing I would look at.
 
  #17  
Old 08-20-06, 05:07 AM
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Originally Posted by mdtaylor
Two pronged appliances have an oversized prong that will only allow the plug to plug in with a certain 'polarity', for lack of a better term.
This is called a polarized plug. However, they are not present on ALL electrical devices, only on SOME of them. They are present when it is desired to force the hot wire to be one of the wires and the neutral to be the other. The appliance will still work if the plug is backwards.

I agree with the others. This job is just too wrong. Run away. Run far away.
 
  #18  
Old 08-20-06, 08:16 AM
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Many thanks for all your suggestions and recomendations on how to better access what could be happening here.

I will take a look at the outlets and try to check the wireing as best I can. I have already ruled out the pwr strip, so I know thats not it.

If I feel its far too complicated then, I will have to hire someone to come take a peek at this situation for us.

Outlet diagram

(L) (R)

(Grnd)

With meter conected at the outlet or strip:

(grnd) to (R) I have 120VAC
(L) to (Grnd) I have .002 VAC or so volts.

Regards,
 
  #19  
Old 08-20-06, 10:10 AM
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What do you get between L and R.

How did you rule out the plug strip?
 
  #20  
Old 08-20-06, 10:32 AM
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Proton, you mentioned (L) and (R) to gnd but you haven't given us a reading (L) to (R) . In a perfect world, you would normally read 120 volts. If you don't get that type of reading when you test, it's an indication that you may have an open neutral somewhere and it doesn't have to be there. That can be anywhere in that particular circuit. There are many possibilities of this situation that you may not have the know how to correct it. You are still at that receptacle, are there any others with the same problem, have you checked any other receptacles? I may be wrong because my eyes aren't looking at it. You will get 10 different answers from 10 different electricians on this particular situation. Everyone here has given good ideas on what could be the problem. There are still questions left to be answered. good luck.
 
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