Voltage on Washing Machine frame; I am baffled.

[brantmacga]

I could not solve this one.

I’m attaching a pic below of the layout. This is a laundry room in a single family home, approx 50/yrs old, 2-wire conductors no ground, steel boxes. No accessible attic above laundry.

Washing machine has 37v on the frame when measured to any neutral or frame of adjacent dryer. LG front load washer, approx 2/yrs old. Customer said they’ve had the problem since they bought this machine and didn’t notice it with the old machine. Dryer has arcing marks on the side from contact with washer; washer doesn’t show the same marks, possibly then from the old washing machine.

The circuit is wired as a star topography from the overhead light. Home run to fixture box, 2-wire switch leg, and 2-wire to the washer and freezer receps.

Here are the steps I performed. Washing machine is Circuit #10. Scroll down to bottom and look at the sketch I made before you read through this.

1) Customer complains they feel a “tingle” if they touch washer and dryer simultaneously. Check voltage from metallic washer frame to adjective dryer frame, measure 37v.

2) Measured for voltage between washer and metallic water lines; 0v.

3) Measured for voltage between water lines and frame of dryer, 0v. Also measured to washer neutral, 0v. Measured dryer frame also to neutral of #10, 0v.

4) Turn off circuit #10; check continuity/resistance between hot/neutral of receptacle, none found.

5) Plug washing machine into freezer receptacle (same circuit), check voltage on frame; 37v.

6) Plug washing machine into Circuit #12 and measure frame voltage; 0v. Problem is confined to Circuit #10.

7) Plug washer back into Circuit #10. Turn off every circuit breaker in panel except #10, measure frame voltage; 37v.

8) Swap wiring on breakers #10 & #12, measure frame voltage; 37v.

9) Remove overhead light, break joint down completely. Make up existing home run & cable directly to washer recep, re-energize and check frame voltage; now 67v. Do the same with wire to freezer, connect washer to freezer recep, now 77v.

10) Connect new temporary home run wire into panel, string wire up to overhead box and connect to washer receptacle. Check frame voltage; 67v. Do the same with freezer recep wire, still 77v there.

11) Remove overhead box from ceiling, place camera in ceiling and inspect for damage. No visible damage to cables. No staples anywhere.

12) Reconnect home run wire and switch leg, re-install light fixture. Left receptacle wires disconnected, gave a quote to run wire mold from Circuit #12 recep. Wiring is completely inaccessible in ceiling and walls. Customer using extension cord to run freezer and washer from Circuit #12.

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[LarryFine]

I would install a jumper between the washer and dryer cabinets, then measure the current on the jumper if you're curious.

The change from 37v to 67/77v suggests a line-to-cabinet leakage combined with a line/neutral swap in the ceiling box.

 

[brantmacga]

Another sketch showing wiring topography

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[brantmacga]

I would install a jumper between the washer and dryer cabinets, then measure the current on the jumper if you're curious.

The change from 37v to 67/77v suggests a line-to-cabinet leakage combined with a line/neutral swap in the ceiling box.

I verified polarity of everything. And I also checked for resistance between conductors on every cable in the circuit.

I originally thought a line to ground leak in the washer, but it only happens on Circuit #10, which to me rules out an issue with the appliance.

I did not think of installing a jumper. At one point during this testing I inadvertently touched the washer and felt the shock.

This might be a job for my 60/yr old megger.

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[hillbilly1]

A lot to follow, but since voltage went away when moved to circuit #12? I would say the fault is on the same leg as #12. Is the floor concrete? The voltage may be faulting to it? I can’t remember if you said at one time you had a circuit tracer? (Maybe just an underground tracer?) Should be able to track where the voltage is coming from using it.

 

[brantmacga]

A lot to follow, but since voltage went away when moved to circuit #12? I would say the fault is on the same leg as #12. Is the floor concrete? The voltage may be faulting to it? I can’t remember if you said at one time you had a circuit tracer? (Maybe just an underground tracer?) Should be able to track where the voltage is coming from using it.

The floor is concrete in this room; it’s an addition, rest of the house is a crawlspace. All conductors are overhead.

I moved #10 breaker to #12 space to see if the condition existed on both legs of the transformer, and it did. I used an extension cord to plug the washer into various other receptacles, and it only happens while plugged into the conductors of Circuit #10.


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[hbiss]

Did you try running a temporary cable directly from the panel to the washer receptacle? Then try it connected to the receptacle conductors in the ceiling box?

-Hal

 

[ramsy]

I used an extension cord to plug the washer into various other receptacles, and it only happens while plugged into the conductors of Circuit #10.

Sounds like a relatively higher-resistance Neutral on Ckt#10, with washing machine frame still bonded to neutral.

 

[brantmacga]

Did you try running a temporary cable directly from the panel to the washer receptacle? Then try it connected to the receptacle conductors in the ceiling box?

-Hal

Step 10 I listed, I ran a cable from the panel to overhead box and connected it directly to the cable that feeds washing machine recep. Voltage measured on the washer frame increased to 67v. I moved the temp home run to freezer recep, plugged washing machine in and measured 77v on frame.

I saw the same voltages when I connected the existing home run cable to each receptacle cable individually.


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[brantmacga]

Sounds like a relatively higher-resistance Neutral on Ckt#10, with washing machine frame still bonded to neutral.

It’s a factory cord, and the frame is not bonded to the neutral. I didn’t measure any resistance between cord neutral and cord ground. The premises wiring is 12/2 without a ground.


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[ramsy]

..the frame is not bonded to the neutral. I didn’t measure any resistance between cord neutral and cord ground.

How was cord continuity metered @ Zero Ohms (Neutral prong to Grouding prong), without appliance frame being bonded to neutral.

 

[brantmacga]

How was cord continuity metered @ Zero Ohms (Neutral prong to Grouding prong), without appliance frame being bonded to neutral.

I’m sorry, when I say I didn’t measure any resistance, I mean that the meter showed open line between the two. I see how that wording is confusing.


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[tortuga]

A few years ago I was literally troubleshooting the exact same problem, it ended up being a bad neutral in meter base.

 

[ramsy]

..I mean that the meter showed open line between the two.

You were right to Megger test when possible.

Voltage energizes appliance frame, since frame is not insulated from other wires.

Excellent example of how continuity meters can miss relatively low resistance faults, caught by a 1-second 100v Megger spot.

 

[ramsy]

A Megger display in Mega Ohms scale may look like a bolted fault, until you look close enough to see the fraction (ie) 0.0001, which most continuity meters read as an open infinity.

Most electricians only consider arcing, when considering faults. faults exist without lightning bolts, it's called leakage.

 

[Little Bill]

Did you try unplugging the dryer and checking the voltage? I may have missed something about where all you were checking for voltage to frame or neutral. I say there is a neutral problem somewhere.

 

[synchro]

I used an extension cord to plug the washer into various other receptacles, and it only happens while plugged into the conductors of Circuit #10.

The 2 year old LG washer probably has a VFD in it. Therefore it's likely to have an electrical filter to reduce high frequency common-mode noise on the power cord. Such a filter would have capacitors from the line and neutral inputs to the ground conductor of the washer (which would be bonded to the washer housing). Then if the ground pin on washer's cord is not connected to an EGC (like in the 2-wire circuit you mentioned) some voltage would be developed between the washer's housing and the neutral. The dryer would probably have the neutral bonded to the case if it has a 3-wire cord. And so in this scenario a voltage could be present between the housings of the two appliances.
The filter capacitors mentioned above would have to be small enough so that the current leakage at 60 Hz would not trip a GFCI, but it could still be enough to at least feel a "tingle".

Perhaps one or more receptacles on circuit #12 has a bootleg ground from the neutral to the receptacle ground terminal. A bootleg ground would keep any significant voltage from developing on the washer's housing relative to that of the dryer.

When the cables to the washer and freezer receptacles were connected up separately, perhaps that reduced the capacitance of the wires and allowed the voltage to rise higher. But that's just a guess.

It seems like all of the measurements involving a metallic water line were 0V. So maybe the water line has a break in continuity upstream somewhere.

I have to say the measurements and testing you did was very thorough.

 

[romex jockey]

i'd be checking MBJ's & GEC's Brant

~RJ~

 

[Dennis Alwon]

I can't keep track of all that you did but the first thing I would do is unplug the washer and get readings from dryer to circuit 10 ground. I also would check the cord on the dryer to make sure it is connected and has continuity between both ends- need to disconnect cord entirely to do this...

If this has happened for 2 years- surprise they waited that long- and it only showed up with the new machine then it appears the washer is the issue but I would not trust a home owner assessment although that is something they should know.

 

[oldsparky52]

The eyebrow raising thing for me is that it only happens on circuit #10