One more time (long)

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George Stolz

George Stolz

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Location
Windsor, CO NEC: 2023
Occupation
Hospital Master Electrician
I had a warranty call this afternoon. "Cooktop only has 120V, according to the appliance guy, it needs 240V." This cooktop is mounted in an island, with a 120V downdraft exaust fan integral to the cooktop.

It wasn't my house, I inherited the project when things got slow. I had stopped in previously for a three-second slap-a-blank-on-that warranty call before, so I knew where it was.

Anyway, upon close scrutiny, with my handy-dandy Vol-Con tester I just bought, I discovered that the 'black' phase was open between the junction box at the cooktop, and the panel. Fearing the worst, I went back and forth to the panel to be sure. I started to sweat even more, at the prospect of having to blast out her basement ceiling to put in a new run.

Nagging at the back of my mind was the fact that I knew what some would say: Use that ground before you dare start knocking holes in the ceiling.

As I triple-checked my findings, I pored over my memory of conversations I'd had with people in the past, about what the possible problems could be. This house has a finished basement, which is unusual for a new home we wire. As I remembered back, I recalled someone griping about somebody else accidentally giving the branch circuit for the cooktop to the wall oven, and vice versa. I rememberred something about chopping holes in a finished basement to fix it.

Based on this shady recollection, I decided that there was probably a junction box behind the microwave or the oven, that I was not about to try to find without making some phone calls.

I apologized to the homeowner for the inconvenience, and told her that hopefully, there was a junction box at the break; otherwise, I'd be chopping drywall in her new home to install a new home run.

I decided that if it came down to it, I'd put my foot down and refuse to use the ground if pushed. Let someone else fix it, at that rate.

Now, I'd like to have a discussion about why the practice is bad.
I know it's against code six different ways, but physically, why is it bad? I'd like to get some discussion going, before it happens. (It may never happen, I just like being prepared.)

Thanks,
 
Whoa! Sorry! No, for a neutral.

The 8/3 with ground would become an "8/2" using black and white for hots, and the ground for a neutral for the fan.

Sorry for the confusion.
 
Sorry gang but since I don't have my codebook handy I can't give chapter and verse but the '02 NEC prohibits the nuetral/eq.grd sharing the same conductor. It was actually an exception somewhere in 250 up through the 99 NEC I think.

But the main problem I have with your solution is that if the problem is a damaged cable, you will never know if the conductors you are using are also damaged and are just barely making contact. This can be a timebomb and I find it hard to sleep some nights knowing that I have a few of those out there from my younger years.

Just a thought.

Bob on the left coast
 
georgestolz said:
Whoa! Sorry! No, for a neutral.

The 8/3 with ground would become an "8/2" using black and white for hots, and the ground for a neutral for the fan.

Sorry for the confusion.
Click to expand...

Its bad practice cause cause the what if the sheath is damaged??? What if the ground is spliced somewhere and there is current running thru it, worst case scenerio that the ground doesnt come lose between there and the panel. the Skin of that metal stove or whatever would be hot.
 
No insulation. On the older homes where they shared the neutral/ground you had insulation on the conductor. Then there's the problem of the next guy who happens to try and work on the circuit.

It's just bad juju to do it that way.
 
If its a warranty call then the builder is still in warranty.Find the cause,I`ll bet its a damaged cable from a framer or drywall screw.That way your company will be paid to repair it.A little thing i`ve done is get my flashlight and toner probe turn off every other circuit in the house and run the probe along the drywall where I would have roughed it in.A probe will buzz louder when it passes the area of damage.Quick fixes like grabing a ground only open pandoras box.You have always seemed a very stand up guy don`t go that route.A home owner will get upset that drywall has to be cut but they will get over it when you tell them,Either we cut or it won`t work.I`ve used the probe trick and have found cut wires over and over.
 
George I agree with Bob on the left coast. This is a potential time bomb. I aso agree with his comment about sleeping at night. George I can tell that you are to good of an electrician to ever take use a cheap cheating trick like using a ground for a neutral. Look on the bright side, either someone cut the cable or buried a box and it's not your fault. Find and document the problem and let ever who caused the problem pay for the repair. When I have a problem trying to decide what to do in a case like this I imagine turning on the evening news and seeing that the house just burned and people were either injured or killed ( there is never a real decision to make, you have to do a proper repair ). Good luck George I hope you find that junction box.
 
Thanks for the replies.

I agree most with Paul's response: "It's bad juju to do it that way."

The problem is, I can't offer one solid, electrical-theory-based reason as to why this is dangerous.

I'm perfectly willing to stand my ground based on code alone. I'm hoping someone will offer a compelling non-code-related theory.

The aspect of this that really struck home for me, that spun me on my heels, was the moment that I had no conceivable explanation for the problem. I had a black conductor that had no continuity to any of the others, and showed 80V under no load, 3V under Wiggy load. Replacement seemed like the only option at that moment.

That basement ceiling loomed at me like a speeding bus, and I pictured cutting the holes to get back to the panel. I pictured no other option. Then I looked at that ground like a steak. Then I had a "Blood on the Highway" moment when I was like "Heck no, I'm not using the ground. That's hack work, and dangerous. Besides, I have nothing to do with this."

I did the right thing, and drove away. But the whole drive home was like "Exactly what aspect of it is dangerous?" I'm not saying it's not: but why is it?

I'm all full up on principles. But the logic and theory I have none of. :(
 
The physics behind the ground-neutral separation

The physics behind the ground-neutral separation

georgestolz said:
The problem is, I can't offer one solid, electrical-theory-based reason as to why this is dangerous.
:(
Click to expand...

OK, if you use the bare/ground wire for a neutral, then the ground wire has current flowing through it. Current through a resistance equals voltage. So your bare/ground wire has a voltage to earth. If this bare/ground wire is also connected to a chassis, or a third prong in an outlet, then someone touching that bare metal chassis on the appliance is not touching an object at the same potential as earth. If they put thier hand on the chassis, and another hand on the kitchen sink, they could be in for a nasty surprise! That's the physics behind separating neutrals and grounds.

Usually the voltage on a neutral wire is only a few volts. It could rise to as much as 50-60 volts in a fault situation. Even a few volts could zap someone with wet hands, or a child or a frail elder. Any time you connect the case or the chassis to the neutral wire you are running this risk.

--Lawrence Lile, P.E.
 
Try this!
Not only would it be a code violation but it could also be a possible life threatening safety risk! This piece of equipment utalizes a 2 pole feed and a single pole feed to operate, if you delete the ground conductor and have only the 2 ungrounded conductors and the netural conductor, the netural would serve a dual purpose as the netural and the ground because you would or should still ground the unit to create a ground return path for possible ground fault. If (no say when) the netural conductor is lost there would be no ground return path for a fault and the first person to touch this equipment and a grounded item would become the return path. Dose this help?

edit to remove short circuit.
 
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George 200.6 A tells you why this is not allowed.Also as already stated if one conductor is damaged then the chances are the rest have some type of damage.A few holes are alot less worrysome then fire damage.The chances this could happen are real.I went on a service call last year with another supervisor.Senario was 18 months of a tripping breaker.It would trip intermittently.He had been there about 6 times for the same complaint breaker tripping.Sometimes it would be fine other times it would trip when restet and then hold.He swapped wires get the switched outlet to operate and not get 10 min away and it would trip.He asked me to go with and try and figure it out.I went the breaker was tripping then hold ?????I used my toner probe and ran it along the base board and it buzzed like a hornet at a joint in the 6 in base molding.I told the homeowner we would have to cut the drywall.She agreed when it was opened there it was finish nails through the 3 wire NM.This is a block home with vapor barrier. the entire area around the NM was charred.The only reason this womans home did not burn was because there was water seepage from incorrect grading the sod was 12 ins above the slab and water was seeping getting the furring wet.So a rigged fix would not have been the answer.We replaced the damaged NM and as it turned out the woman had been complaining for 2 years of mold shes allergic to we were paid,she got the mold situation corrected and OH WELL the builder footed the bill.They can well afford it.After all they multipy X 3 for any extras they get the customer to agree to.
 
George, I agree absolutely with Lawrence Lile's explanation (post #11). To that I will add this: With the appliance's chassis connected to the neutral wire, there will be voltage on the chassis (as he said). But that means that every time a person touches the appliance, there is going to be some current flowing through that person's heart. Might not be much, but it will happen. Every time. No exceptions.

As the installer, would you be happy about that? If you said this to the home owner, will they be happy about that? Do you think this is enough to convince them to spend the money (if it's not under warantee) to get this fixed?
 
There were milllions of residential ovens and dryers installed across the country with just exactly that hookup, from the 1940's thru the 1999 code cycle. The documentation is clear, millions of people died of electrocution from the practice, and so finaly after consulting with Canadian experts about the issue, the NEC code was changed. As for you unfortunate types who live in a house wired in the period I like to call the "Dark Ages", be very very careful. Do not approach your oven or your dryer. Keep a careful distance from the thing. P.S. I agree with the rip it out and re-do the wiring. Just in case of the damage to the wiring possibility. Pardon the fooling around in this post, I just happen to think that actual statistics ought to be applied when ever codes are altered.
 
Okay, that makes more sense, I can use that, if the need ever arises.

My honesty can't keep me from sharing the rest of this story. Besides that, I can't help laughing (this morning I was cursing) at my own expense.

You know how I triple checked the panel?

Uh, yeah. It was tucked in behind the lug. I am a total idiot. But I learned a valuable lesson, as my co-worker scolded me: Always take it out, examine it and then put it back in. I looked, and tugged, and it looked right. I feel incredibly stupid.

Just thought I'd share that. :D

Thanks for all the replies.
 
"It was tucked behind the lug"

Isn't that where it should be?:)

I'm glad it was an easy fix .
 
Hey 77401, I was just kidding around. Actually I am all for the change. It is a step up for safety. It worked the other way around, but now it is much safer.
 
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georgestolz said:
The problem is, I can't offer one solid, electrical-theory-based reason as to why this is dangerous.
Click to expand...

George it does not matter.

It is wrong period.

You want to be a professional than act like one. (As you have always seemed to here) :)

It's had been done for years with dryers, ranges and cook tops now the rules have changed.
 
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