LG wall oven and microwave all in one unit, panel upgrade, liability issue concerning using EGC as neutral.

M

MagneticVane

Member
Location
Rochester, NY
Occupation
Electrical contractor/electrician
Hello guys, I am having issue with my business partner, customer and other contractor over something that I can see as a clear violation on the code requirements, and I happened to understood this code perfectly clear, EGC and Neutral shall not date with each other after either the main disconnect or the main panel throughout the building wiring. First of all, few weeks ago a general contractor that got nothing to do with us, installed a single wall unit combo of Microwave oven and convection oven made by LG, they said not to touch anything on that unit, otherwise they will void the warranty. I am not going to touch on that part which is fine by me. My real issue is that I am upgrading a panel, from Challenger to Square D, and note that the cable for the oven combo unit was 3 wire, I am aware that the microwave oven run normally at 120v, so therefore neutral is required, and I brought up this issue with my partner and he went into defense mode and telling me not to worry, damn it, thanks Mike Holt for the education on EGC 101, I can't just shut up and walk away thinking of what could happen in the future, not going get into that detail as you know what I am talking about. I had to look up on LG website for this model. I was indeed surprised to note that the manufacturer clearly state that 4 wire is required, also realizes that the cable used might be a size too small, got my partner challenge me even more, said that I am not responsible for anything if something happens. I am not sure whether I should shut up and let it go because the permit I pulled got nothing to do with oven combo installation, just the panel replacement and I have no idea if they (Other contractor) obtain a permit for the oven/microwave installation and if so, how come they passed an inspection at their end? My partner suggested we talk with the inspector and go from there, I am curious what are your thoughts, feedback?
 
sounds like the oven installation is not your responsibility or in your contract. That said, make sure you install the correct breaker for the attached load and don't exceed the limits of the wire size. If the ovens are too large for the existing circuit, they need to be upgraded "change order".
 
MagneticVane said:
general contractor.. installed (oven listed for 4 wires, on existing 3-wire cable), they said not to touch anything on that unit, otherwise they will void the warranty.
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There's more risk with house flippers than any one electrical-hazard they install. Accident claims with illegal activity create a lynch mob.

Panel flipper paper trails make them an easy target, with no other responsible-party present to face the hanging judge, except the owner.

Accident attorneys may get owners off the hook, if panel flippers so much as provide an extension cord, or coordinate-power interruptions. My state disciplines licenses for aiding, abetting, or conspiring with unlicensed persons, per B&P § 7114, with fines up to $15,000.

Proof of indemnity could be a defense, if the panel flipper contract, and evidence, demonstrate a separation of project schedules.

Trying to document hazards, or recommend abatement, at the scene of the crime, is less likely to overcome "Joint and Several Liability."
 
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The 3-wire oven circuit was legal and is still legal as existing. You are fighting a losing battle. It is outside of your lane. But you should have something in your contract stating that you take no responsibility for the state of the existing wiring beyond what you immediately touch at the panel.
 
curt swartz said:
What type of cable is being used? It was never permitted to use a equipment ground conductor as a neutral conductor.
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3 conductors, much similar as service entrance cable instead of supposedly 4 conductor cable as required in mfg manual. I was surprised of a microwave oven build in wall oven See link: https://www.lg.com/us/cooking-appli...sG6BpZb08DaXpYJK9mCCCoskcuI-Hj6RoCW7AQAvD_BwE customer bought house, pretty much mansion, not a flipper and the house was build in mid 80's, he replaced from dual wall oven to the product shown in link because he thinks having 2 ovens is pointless and wants microwave and oven in 1 so he had it installed about 3 weeks ago. In other word, the GC does not want replace the cable to 4 wire, probably to save their money, IDK, also to replace these 3 conductor to 4 conductor is not that hard for this job, basement is unfinished, and only about 20 feet from where the panel is to the oven.
 
As mentioned above, it has been acceptable to wire new 4-wire appliances to existing 3-wire circuits since the change to 4-wire circuits, as long as the rules were met, such as SE or insulated neutral from main panel.
 
jim dungar said:
Who converted the manufacturer's 4W terminals to be compatible with the 3W circuit? Haven't they already voided the warranty?
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That is not my concern, I got nothing to do with warranty, that why I had to respect the customer by not touching that end (It's between the customer and GC). my only concern is that I could end up a target in a lawsuit that I hope that it won't happen, and how do I protect myself from misdirected lawsuit? I am grateful for some members good feed backs
 
MagneticVane said:
That is not my concern, I got nothing to do with warranty, that why I had to respect the customer by not touching that end (It's between the customer and GC). my only concern is that I could end up a target in a lawsuit that I hope that it won't happen, and how do I protect myself from misdirected lawsuit? I am grateful for some members good feed backs
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The manufacturer allows the appliance to be used on a 3-wire circuit and so does the code. You are covered and legal. I would be more concerned about HOW the GC made the connection than with the bonded neutral. My guess is that he probably didn't make the splice in a box and there are now wire nuts shoved in the wall.
 
MagneticVane said:
3 conductors, much similar as service entrance cable
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I believe Florida has a high casualty rate from lightning while land-line phones are held to their ear.

If casualty occurs from a neutral-energized frame, due to lightning strike, utility excursion, or inside wiring defect, listed instructions for 4 conductors may get appliance manufacturers off the hook.

Listing violations shift liability to installers.
 
ramsy said:
I believe Florida has a high casualty rate from lightning while land-line phones are held to their ear.

If casualty occurs from a neutral-energized frame, due to lightning strike, utility excursion, or inside wiring defect, listed instructions for 4 conductors may get appliance manufacturers off the hook.

Listing violations shift liability to installers.
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How would the neutral being bonded to the frame be any more of a problem with lightning than having a separate ground wire?

Also, the manufacturer allows connection to a 3-wire circuit.
 
CoolWill said:
How would the neutral being bonded to the frame be any more of a problem with lightning than having a separate ground wire?

Also, the manufacturer allows connection to a 3-wire circuit.
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No lynch mob, or hanging judge, unless aiding and abetting illegal activity.

No liability for following the listing.
 
CoolWill said:
How would the neutral being bonded to the frame be any more of a problem with lightning than having a separate ground wire?
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Missing electrodes, cut, or hanging, is more common than un bonded neutral to EGC at service equipment, but neither play well with lightning.

That separation causes lightning to jump around the house, with wiring at different potentials.

Illegal activity is the link in the chain of events that alarms the courts, which make examples of anyone helping unlicensed contractors.
 
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CoolWill said:
The manufacturer allows the appliance to be used on a 3-wire circuit and so does the code. You are covered and legal. I would be more concerned about HOW the GC made the connection than with the bonded neutral. My guess is that he probably didn't make the splice in a box and there are now wire nuts shoved in the wall.
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Not this one, please read my post again, especially when it comes to manufacturer specs in the owner manual, it clearly stated that 4 wire is required.
 
CoolWill said:
SE cable

No. The manual, on page 10, specifically allows the appliance to be used on an older 3-wire bonded neutral circuit. The OP must have missed that.View attachment 2577369
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Not according to this specific model owner manual, they specifically clearly required a 4 wire 240V at 50a. No other available option. I was surprise and my first to see that mentioned in the manual! There is a link for this specific model and you can check it out.
 
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