OT Anyone want to help with a home wiring problem ?

Since the members of this board have knowledge on almost all topics I thought I would trough this one out there.

My wife and I have lived in a very old farm house for over 20 years. From the day we moved in we found that if one touches the stove and the sink (stainless steel with no disposal) at the same time the result will be a pretty substantial shock.

So, not wanting to jump in too fast, I've decided to look into fixing this after 20 years... :)

I put a volt meter between the stove and the sink and measure 110 volts.

My original diagnosis was that the stove could not be the problem. Since it is 220v and requires both hot legs of the circuit to operate, I figured it could not be wired incorrectly.

So, I have checked the wiring for the light over the sink and the electric outlet near the sink on the kitchen counter, but everything seems to be in order there. While the breaker was off for those circuits I measured 110v between the stove and the sink.

Finally I turned off the breakers for the stove, and bingo, no voltage between the stove and sink.

So now I am assuming the stove is the problem, but I'm stumped as to what the problem could be. It's a little bit of a job to get it out of the counter and away from the wall, so I'd like to have an idea what I'm looking for before I start tearing into things.

Any thoughts on this ?

Thanks,

-Steve
 
Each leg of the 220v for stove is 110 when measured relative to ground. One of those legs has a leakage to the stove housing somewhere inside. Another possibility is that the 3rd wire which is neutral in such an old stove is not really neutral and is hot. Modern day stoves will be 4 wire where the 4th wire is a safety ground, but it is not likely that you have that 4th wire. I would find the connection of stove to house wires & measure the neutral relative to a cold water metal pipe to verify a neural is not hot. To get some idea as to whether this is a hard short or a leakage, you could connect a light bulb from stove to sink & see if it lights or not. Open the stove top & do a visual, moving wires around looking for damaged insulation. Do all functions of stove operate properly?
 
I am going to guess that the stove isn't grounded. My thought is that one of the hot legs is getting to the stove body. While the stove uses 220
volts, the lights and timers etc. use 110 that is taken off of one leg to ground, and I think this path is letting the body of the stove become
energized. The sink is quite likely pretty well grounded. I would pull the stove out, disconnect the power, and look for continuity between each
leg and the stove ground terminal.

Jerry
 
Ahh, this forum is such a valuable resource !!

Yup, I agree with both of you. I was stuck on the stove being wired incorrectly, I hadn't considered that there was leakage from one leg to ground.

Now I have an idea of what to look for. I'll start work on this tomorrow and report back.

THANK YOU !!
 
So likely that in changing this equipment into the "fixed" mode, a couple of things will have changed. first and most important the safety (chassis) ground circuit pathway from the stove body all the way back to the breaker panel and then out to the stake in the ground will be intact, and bonded in such a way so that this ground circuit pathway will be the path of least resistance (as compared to the power wiring) and current capable beyond the circuit breaker or fuse rating. second, and important for function, there will be no current pathways (leaks or shorts) between any 110 hot wire or control component and the stove frame.

the stove likely utilizes "calrad" style elements. these are known to exhibit current leaks of several megohms without being "defective". i would eliminate all leaks in wiring and control devices, and since i cannot change the fact that calrad elements do leak, i would rely on that strong bonded chassis ground to force the frame of the stove to "zero volts ac" as measured against any other grounded device (sink?).

btw: a damaged calrad element may be shorted to ground rather than just a bit leaky.

cheers!

jg
 
The things I would check first would be the outlet that the stove is plugged into is wired correctly, and the power cord where it connects to the stove itself is also connected correctly.
I wouldn't bother with the other suggestions [u:563db111da][b:563db111da]UNTIL[/b:563db111da][/u:563db111da] these two have been checked and corrected (if necessary).
You'd be surprised how many things appear to work just fine with the polarity reversed, and the only issue is getting a reVOLTing experience when operating it.
Years ago in my first house, I went to shut off the power in the garage (had an old fuse box with a shut-off built in to it) and got "bit" every time I even touched it. I got out my handy dandy multi-meter and started checking voltages to discover that the hot and neutral wires were crossed on the fuse box itself. Once I corrected this, it no longer "bit" me. Yet before fixing it, everything I plugged in to the outlets, along with the lights (fluorescent) worked just fine.
 
Well I think I have this problem fixed.

I pulled the stove out from the wall and quickly found no resistance between ground and one of the legs marked L2. L2 had red wires attached and L1 had black wires.

I started taking panels off the back of the stove and here is what I found:

OvenRat.jpg


Yikes !! I doubt that he suffered very long... :eek:

Note to the left of the rat is the clock/timer assembly, and note the 3 wires with spade lugs - Black, Red, and Yellow.

I removed the rodent, but of course L2 still showed continuity to ground. I futzed around for a while and then started removing red spade lugs to try and isolate which component might be causing a problem. Sure enough, when I removed the red wire from the clock/timer assembly my VOM showed no continuity to ground.

The clock/timer never worked since we moved in the house, so I had no interest in trouble shooting any further. I taped up the end of the red spade lug and put it all together. Everything seems in order now.

But, I have a few comments and questions.

1) I suppose it is possible that the rat caused an internal short to ground in the clock/timer, or it may have just been coincidence, but in either case I assume there is a short within the clock/timer and that was the root cause of my problem.

2) What I don't understand is why a breaker didn't blow. I didn't try JMOR's suggestion of putting a light bulb across the stove and sink, but I can tell you that touching those 2 items resulted in a pretty big shock, so I assume that there was pretty much current bleeding to ground. Since the stove body is grounded to the middle wire of the pig tail, why didn't a fuse blow, or why didn't whatever is shorted in the clock/timer melt ?

Thanks again for everyone's help !!
 
If the stove were to be properly grounded it would not shock you. Unless the stove IS grounded and the SINK IS HOT... That would be a completely different problem.

The clock motor winding is 99/100 times 120V. One side to line, other side to neutral (4 wire system) or ground (3 wire system). It will look like a short to your Ohmmeter which uses DC for measurement.

You need to check the wiring from the stove all the way back to the panel. Somewhere there is a loose or corroded connection, or the wire itself may be compromised. Often those circuits were wired with SE cable which has a bunch of fine wires spirally wrapped around the power conductors for ground. If the insulation is compromised (chewed by rats) those wires can corrode and the ground circuit becomes broken.
 
(quoted from post at 17:33:53 07/29/17) If the stove were to be properly grounded it would not shock you. Unless the stove IS grounded and the SINK IS HOT... That would be a completely different problem.

The clock motor winding is 99/100 times 120V. One side to line, other side to neutral (4 wire system) or ground (3 wire system). It will look like a short to your Ohmmeter which uses DC for measurement.

You need to check the wiring from the stove all the way back to the panel. Somewhere there is a loose or corroded connection, or the wire itself may be compromised. Often those circuits were wired with SE cable which has a bunch of fine wires spirally wrapped around the power conductors for ground. If the insulation is compromised (chewed by rats) those wires can corrode and the ground circuit becomes broken.

Given the age of the house I'll bet dollars to donuts the circuit is 3 wire....

TOH
 
(quoted from post at 15:20:22 07/29/17)
(quoted from post at 17:33:53 07/29/17) If the stove were to be properly grounded it would not shock you. Unless the stove IS grounded and the SINK IS HOT... That would be a completely different problem.

The clock motor winding is 99/100 times 120V. One side to line, other side to neutral (4 wire system) or ground (3 wire system). It will look like a short to your Ohmmeter which uses DC for measurement.

You need to check the wiring from the stove all the way back to the panel. Somewhere there is a loose or corroded connection, or the wire itself may be compromised. Often those circuits were wired with SE cable which has a bunch of fine wires spirally wrapped around the power conductors for ground. If the insulation is compromised (chewed by rats) those wires can corrode and the ground circuit becomes broken.

Given the age of the house I'll bet dollars to donuts the circuit is 3 wire....

TOH

Yup, it is a 3 wire system.

I did not check the ground connection in the house wiring, I agree, if the house ground circuit is faulty, that would explain the behavior I was seeing.
 
I hadn't thought about the old electrocuted rat in the stove problem in a while. When I worked at the phone company we would occasionally
have electrocuted snakes mess up some equipment. I don't think that the rodent affected anything, although he would have started to smell
really bad pretty soon, you stated that this shocking problem has gone on for a while, yet he looks pretty fresh. You can take your multimeter
and look for continuity between your sink, and the ground on any handy 110volt receptacle. Or, look for a voltage difference. My guess is that
the sink and ground are the same. The clock timer sits between a hot leg, and chassis ground. While it let 110 volts pass to the chassis, it also
limited the current. My though is that the current was below the threshold of the fuse or breaker, so nothing tripped. You could also check
between the stove chassis and the handy receptacle ground earlier to ensure that the stove is actually grounded. It might not be connected
back to a good ground, rats might have chewed the wire somewhere in the basement, or some other problem may yet appear. It's quite
possible that you've fixed it by eliminating the clock, it could be shorted to its chassis internally. Good job on the troubleshooting!

Jerry
 

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