GE induction cooktop

[BrianOC]

I was working in a residential panel installing a surge protector; while terminating the grounding conductor I decided to move another grounding conductor to another higher terminal to maintain a neat appearance and to keep the wires from the surge protector as short as possible (as specified in the surge protectors instructions). As I disconnected the EGC that I wanted to move, I wound up getting shocked (I was holding the bare conductor in between my thumb and forefinger and my forearm on my opposite arm came in contact with the panel frame). After deenergizing the panel I traced that offending bare copper EGC back to a 6/2 nm cable feeding a GE induction cooktop. I cleared the bare copper EGC from all wires and metal and reenergized the panel. A test between the EGC and the neutral/ground buss gave 110 volts. I figured a neutral was tied into the ground from the cooktop since it was a 6/2 feed. Checking the junction box at the cooktop revealed only two hots and a green insulated ground. Everything seemed fine on the branch ckt: no over driven staples, over tightened connectors, good splices at the junction box. I reconnected the EGC at the panel, and opened the splice at the junction box. Once again 110 volts between the appliance ground and the ground from the panel. Just to be sure, I removed the EGC from the neutral/ground buss again and tested between the EGC and ground; with the branch EGC still disconnected from the appliance ground I got 0 volts which means the issue is at the appliance not on the branch wiring. Testing between the appliance ground and the hot wires resulted in: 230 volts to black and 11.4 volts to red. I was wondering maybe one of the induction coils might be grounded somewhere, but the weird thing is that the appliance works fine and I did not detect any significant leakage current on the ground with my amp probe (but I do not think it would pick up anything in the milliamp range). The only other thing I could think of is maybe there is a low voltage application for the control pad or indicator lights that might require a neutral but it seems unlikely that GE would miss something like that. I looked at the service manual and It gave no indication of a transformer anywhere in the cook top. GE technical support was not helpful as they had no electrical knowledge whatsoever. I eventually pestered a consumer relations rep into giving me an actual GE tech support number for GE techs. The technical rep was skittish about talking to me because I did not have an account with them but I managed to beg a minute of his time. After hearing my story his only response was why I was working live? I admitted that my failure to follow proper electrical safety procedures was regrettable, but not quite the point of my call. He recommended I have the home owners call for service but admitted a tech would most likely see that it was working properly take off.
Has any body heard anything similar, have any idea what the problem might be, or know what my next step might be?
I was wondering if it would be possible for the cooktop to operate properly if one of the induction coils was grounded or if there would be enough leakage current detect. Unfortunately I did not have enough time to do a lot of testing and I really don?t think it would be wise for me to start taking apart an expensive new cooktop since I?m not experienced in appliance repair.

thanks
brian

 

[iwire]

Brian welcome to the forum, try hitting the enter key once in a while to make reading easier.

 

[nakulak]

would have been nice if you had checked the amperage on the offending egc (if I missed it I beg your pardon).

 

[Buck Parrish]

It sounds like some thing else might be tied to it.
Is it possible an old gas line's grounding is still bonded to the stove top some how.

 

[LarryFine]

Brian, welcome to the forum!

Pardon the early criticism, but one humongous paragraph is hard to read, so, if you don't mind, and in the interest of reading:


I was working in a residential panel installing a surge protector; while terminating the grounding conductor I decided to move another grounding conductor to another higher terminal to maintain a neat appearance and to keep the wires from the surge protector as short as possible (as specified in the surge protectors instructions).

As I disconnected the EGC that I wanted to move, I wound up getting shocked (I was holding the bare conductor in between my thumb and forefinger and my forearm on my opposite arm came in contact with the panel frame).

After deenergizing the panel I traced that offending bare copper EGC back to a 6/2 nm cable feeding a GE induction cooktop. I cleared the bare copper EGC from all wires and metal and reenergized the panel. A test between the EGC and the neutral/ground buss gave 110 volts. I figured a neutral was tied into the ground from the cooktop since it was a 6/2 feed.

Checking the junction box at the cooktop revealed only two hots and a green insulated ground. Everything seemed fine on the branch ckt: no over driven staples, over tightened connectors, good splices at the junction box. I reconnected the EGC at the panel, and opened the splice at the junction box.

Once again 110 volts between the appliance ground and the ground from the panel. Just to be sure, I removed the EGC from the neutral/ground buss again and tested between the EGC and ground; with the branch EGC still disconnected from the appliance ground I got 0 volts which means the issue is at the appliance not on the branch wiring.

Testing between the appliance ground and the hot wires resulted in: 230 volts to black and 11.4 volts to red. I was wondering maybe one of the induction coils might be grounded somewhere, but the weird thing is that the appliance works fine and I did not detect any significant leakage current on the ground with my amp probe (but I do not think it would pick up anything in the milliamp range).

The only other thing I could think of is maybe there is a low voltage application for the control pad or indicator lights that might require a neutral but it seems unlikely that GE would miss something like that. I looked at the service manual and It gave no indication of a transformer anywhere in the cook top. GE technical support was not helpful as they had no electrical knowledge whatsoever.

I eventually pestered a consumer relations rep into giving me an actual GE tech support number for GE techs. The technical rep was skittish about talking to me because I did not have an account with them but I managed to beg a minute of his time. After hearing my story his only response was why I was working live?

I admitted that my failure to follow proper electrical safety procedures was regrettable, but not quite the point of my call. He recommended I have the home owners call for service but admitted a tech would most likely see that it was working properly take off.
Has any body heard anything similar, have any idea what the problem might be, or know what my next step might be?

I was wondering if it would be possible for the cooktop to operate properly if one of the induction coils was grounded or if there would be enough leakage current detect. Unfortunately I did not have enough time to do a lot of testing and I really don’t think it would be wise for me to start taking apart an expensive new cooktop since I’m not experienced in appliance repair.

thanks
brian

 

[cadpoint]

....A test between the EGC and the neutral/ground buss gave 110 volts. I figured a neutral was tied into the ground from the cooktop since it was a 6/2 feed.

Checking the junction box at the cooktop revealed only two hots and a green insulated ground. ...

:-? Where'd that Go!

I'd megger the circuit it and surrender your results that you line is ok!

The servicing for individual prioriorty equipment is now a big business, I think you only need to qualifiy the service to it.

Welcome Abroad!

 

[jeremysterling]

I figured a neutral was tied into the ground from the cooktop since it was a 6/2 feed. Checking the junction box at the cooktop revealed only two hots and a green insulated ground.

The red conductor must power a clock or timer motor or some such 120V load (in addition to the heater element) and the EGC is being pressed into service as a neutral.

Now, most ranges (and AHJ) call for a four-wire 14-50R receptacle instead of the old school three-wire 6-50R. Sounds like yours is hardwired though...

When I first started in the trade, I would land my new circuit's noodle and ground in the hardest to reach holes, therefore saving the easier terminals for the "next guy." After twenty years, I am the "next guy" and I will not remove or disturb other wires to terminate mine.

I have and will continue to troubleshoot utilization equipment. But I'm with cadpoint on this one. Give the premises wiring a thorough check and call it good. Make the customer aware of the hazard and sell and pull a neutral. Unfortunately, the neutral will be a #6.

I've seen where the neutral for the range hood was used for the 120V component of the range. Not legal so don't do it.

Welcome to the forum!

 

[George Stolz]

110 volts between the appliance ground and the ground from the panel.

Testing between the appliance ground and the hot wires resulted in: 230 volts to black and 11.4 volts to red.

Where were you testing at this time, and between what two conductors?

After hearing my story his only response was why I was working live?

I will take that form of criticism from a fellow electrician, but I do believe I would unleash a string of profanity onto a self-righteous appliance-phone-tech-support guy for saying anything of the sort.

He recommended I have the home owners call for service but admitted a tech would most likely see that it was working properly take off.

I would take down this guy's name and number, and demand to speak to his boss. If the feeder's EGC were to have opened, then the entire home's equipment grounding system would be energized by his defective product, and he _____-well better be ready to replace it or face a lawsuit. A limp-wristed phone tech guy claiming he can't communicate with his own techs the purpose of the service call is going to sound extremely hollow in court.

There comes a time to light a fire under your temper, I believe this is just such an instance.

 

[BrianOC]

Thanks for all the posts guys and I apologize for the monolithic block of text.

Buck Parish- there is no other circuit tied into the cook top. The basement is unfinished and I was able to inspect the cable all the way to the junction box just below the cooktop.

Nakulak- I did put a clamp on amp probe on the EGC and was unable to detect any leakage current. I did put that in the original post but I imagine you got lost in the forest like everyone else.

Cadpoint- What I meant to say was that opening the junction box revealed only two hots and an insulated ground ?coming from the appliance?, meaning that the electrician who connected the appliance did not connect the neutral to the ground, because there was no neutral. Sorry for that.

Also, as far as meggering the branch circuit, I thought that I had verified that the branch wiring was ok by disconnecting the grounds at the junction box below the cooktop, and disconnecting the branch EGC from the panel and testing to the branch EGC in the panel to the panel?s neutral/ground buss- which gave 0 volts.
Once again, I?m sure you missed that because of my not breaking up my post into paragraphs. I suppose I could still megger the ckt? but then you would have to lend me you megger.

Jeremy sterling- I was figuring along the same line that there was a lower voltage application for controls, however, there were only 2 hots and a ground coming from the appliance.

Also, the installation guide specified that a neutral was not necessary. This is brand new appliance (only been installed for two months), it seems unlikely that GE would commit such an error? but recalls happen all the time I suppose.

Yes the cooktop is hardwired at the junction box. I understand why the electrician who connected the appliance did this- because the manufacturer supplied whip from the appliance is flexible metal conduit. I have not seen any range plugs that will accept a flexible metal conduit (perhaps someone can direct me to a product that would work in this situation).

thanks a lot guys
Brian

I know i could have used quotes and other functions that would help in posting but i'm going to need to take some time to figure that out, right now i just want to reply as quick as possible.

 

[BrianOC]

hey George, thanks for your reply

At the junction box below the cooktop with the EGC from the appliance and the EGC from the branch ckt disconnected, but with the hot wires still connected I took voltage readings:

from appliance ground (disconnected from branch ground) to black (both wires from appliance and branch connected)- 230 v

from appliance ground (disconnected from branch ground) to red (both wires from appliance and branch connected)- 11.4

between the two disconnected grounds- 110 volts

I don't know if i made this clear before but I am not a GE tech, but i did manage to get the number of a tech support line for GE techs. He did not want to communicate with me because you need to have an account with this particular Support line. Just like this forum won't give info to DIYer's, I suppose this guy had the same rationale.

Before I light my temper, I just want explore all the possibilities... so I don't end up looking like an idiot.

I suppose my next step is to instruct the homeowners to have a certified GE service tech look at the cook top, and I'll leave a note to him explaining the problem with visual aids of my tests, so he doesn't take off prematurely.

If he verifies that the cooktop it functioning as it is intended, and signs off on it... then i'll have a leg to stand on with GE, and a little more confidence to get nasty when necessary.

once again, thanks a lot for your post George

 

[George Stolz]

There is a small chance that the 110v between L-G is induced onto the frame of the range. To eliminate this as a possibility, you would measure between the two points with both a low-impedance tester (such as a Wiggy or Vol Con) and a digital multimeter (DMM) at the same time. Alternately, you could use a DMM with a low impedance adapter.

The Wiggy would drain any induced voltage while the DMM would be telling you the end voltage after the load is introduced. If the Wiggy immediately tells you that you have 110v, then you can omit the DMM from the process.

If the voltage drops to near nothing when you add the Wiggy into the mix, then it is induced voltage and my fury with the tech guy would be uncalled for (idiotic ). However, since the voltage is very close to a nominal value (the voltage from L-N), and you got a decent shock from it, I'd bet that there is a load inside the appliance that uses the ground as a neutral (either intentionally or not).

This would be the only test for me, to determine whether to get GE in there to replace it.

 

[iwire]

I suppose my next step is to instruct the homeowners to have a certified GE service tech look at the cook top, and I'll leave a note to him explaining the problem with visual aids of my tests, so he doesn't take off prematurely.

If he verifies that the cooktop it functioning as it is intended, and signs off on it... then i'll have a leg to stand on with GE, and a little more confidence to get nasty when necessary.

once again, thanks a lot for your post George

If the building wiring is fine I would be done, it would be written up as an issue that the HO would have to deal with. There would be nothing to get nasty about with anyone.

 

[George Stolz]

Good point. Sometimes I take on more stress than I should worry about.

 

[BrianOC]

George- "you would measure between the two points"

-would this be from line to the ground with the EGC disconnected from the neutral/ground buss in the panel.

by, the way, where the heck do you learn this stuff

I did get a significant shock though, so i'm assuming it's not induced.

 

[BrianOC]

iwire- point taken. However, I'm just curious about what's happening... and I figured i'd learn a thing or two if I saw it through.

 

[George Stolz]

George- "you would measure between the two points"

-would this be from line to the ground with the EGC disconnected from the neutral/ground buss in the panel.

Yes.

by, the way, where the heck do you learn this stuff

Right here.

 

[BrianOC]

well, once again, thanks for all the advice... I will post again when I have new information or results.

 

[gar]

091127-2038 EST

BrianOC:

Assuming you have a decent DVM you can likely measure low AC currents. My Fluke 27 can measure microamps with a resolution of 0.1 microamp. However, a while back I blew the internal fuse. For your type of test I do not recommend using the the current range. Rather use an external resistor as a shunt and use the meter in a voltage position.

Suppose you wanted to read 1.0 V for 10 MA, then the resistor would be 1/0.01 = 100 ohms. Power dissipation would be 1/100 = 0.01 watt. Therefore, you could use a 1/4 W resistor and these are cheap. If some how the circuit tried to force 1 A thru your test resistor it would burn up. No problem a few pennies lost.

I suspect that you have a low level of leakage current. This resistor for measuring leakage current would be placed between the ground wire from the range top to the EGC. On second thought, a 10 W wire wound resistor would be a better choice because it is more mechanically rugged to connect to your existing wires. Another possibility is to use an inexpensive 1500 W heater. This has a resistance of about 10 ohms so your voltage would be about 0.1 V for 10 MA.

.

 

[BrianOC]

george- your test worked, with the wiggy in the mix the DMM dropped to about 10 volts.

When testing with the wiggy alone: the wiggy's led would light for an instant but it would never register an actual voltage.

I guess i'll be carrying two testers from now on.

once again... thank you all