OT: Electrical

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My electric oven is on its own 220V 50amp circuit. It recently started to throw a GFI outlet on a separate circuit (110V) when my wife turned the oven light on. Now it's started to throw the same GFI at random times even when the oven is not in use.
I checked the GFI receptacle w/ a three light tester and it shows all three lights on but dim. When I unplug the oven (on the dedicated 220V circuit) the 110V GFI checks out 'correct' with the tester.
What the heck is going on? My gut tells me that the stove (15 years old) has a component that has gone belly up.
Anyone have any thoughts on this?
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snipped-for-privacy@garagewoodworks.com wrote:

My non-professional guess is that the GFI receptacle has gone "bad", and that the tester isn't sensitive enough to detect the problem. To me, swapping out the receptacle seems like the obvious step to take before calling a professional. Your mileage may vary based upon your wisdom and experience. You have me curious, please report how it works out.
Bill
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On 7/11/2013 12:18 AM, Bill wrote:

Replace GFI, ~$10.
Replace oven, $100's.
Course of action seems clear.
js
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snipped-for-privacy@garagewoodworks.com wrote in

Probably, the cables for the two circuits are close together, and the current in the oven circuit is inducing a small current in the other circuit -- causing nuisance trips in a failing GFCI.

I agree with Bill: first thing I'd do is replace the GFCI; it's a cheap and easy job. If the problem goes away, rest easy. If the problem persists, it's time to talk to an electrician.

I agree that something's gone belly up, but IMHO it's far more likely to be the GFCI.

One last thought: post in alt.home.repair instead of here. There are at least two licensed professional electricians who read and post there regularly, and their advice is to be trusted: "RBM" and "gfretwell".
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On 7/11/2013 6:21 AM, Doug Miller wrote:

...
Induced currents from the oven circuit when not in use????
I'd agree w/ the GFCI being the likely culprit or there's an intermittent on that circuit and the oven is basically a red herring.
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On 7/11/2013 6:48 AM, dpb wrote:

Some of the newer GFI's now detect a slight problem with say a bad wire on a lamp cord, no short, but too much resistance. The oven probably is using some current all the time, such as the clock.
I would suspect the GFI becoming way too sensitive to that possibility.
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On 7/11/2013 7:03 AM, Leon wrote:

When there's nothing but the clock and whatever other micro-processor loads only, the current flow to the range is miniscule. If that were able to induce sufficient current to trip the GFCI in the second circuit it would never stay on, not trip randomly. I stick w/ contention it's more than likely unrelated to the range even tho I agree w/ the fault probably associated w/ the GFCI itself.
Your example is a fault on the circuit in question, not some phantom induced current from another circuit. Think it highly unlikely since the problem now appears to be independent of the use and previously only coincidental. Probably there's another appliance or particular light or somesuch that is used when the range is used that was the culprit in initiating the trip.
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On 7/11/13 7:03 AM, Leon wrote:

While you're checking this other stuff, check the main 220v receptacle for the oven. I don't know how old your house is, but they were using aluminum wire for high current 220v to ovens and furnaces back in the day. Most receptacles have copper connection. Aluminum to copper can spark and it ends up melting the insulators and can be dangerous, obviously.
Check your wire connections to the receptacle in the box in/on the wall to see if this is happening. If you do have aluminum wire, you don't have to replace it. They make retro-fit receptacles with aluminum connectors or copper that uses a dielectric grease to stop sparking.
--

-MIKE-

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Not spark...
When dissimilar metals are in contact, they can galvanically corrode. The corrosion causes additional resistance, which leads to heat build-up. The heat can build up to the point where nearby combustible materials will, well, combust.
Aluminium conductors also expand and contract with temperature changes more than copper; in smaller (AWG 12) gauge connections this may loosen the connection over time, which also increases resistance which leads to heat, which can lead to fire. This generally doesn't happen with the connectors used for #6/#4 50A 220V recepts, if they are torqued correctly when installed.
Brian's problem is likley to be a loose neutral somewhere, or a a three-wire 220 circuit injecting current into a shared ground because the appliance (stove) is cheating by using one 220VAC leg and the ground to get 120V for the oven light (since a three-wire circuit won't have a grounded conductor, only a grounding conductor).
scott
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On 7/11/13 12:36 PM, Scott Lurndal wrote:

Opinions among electricians are as varied as among woodworkers. :-)
My buddy who is an EE with AEP told me when those connections do end up loosening because of the reasons you describe, they will often spark, causing a fire.
Whatever the specifics, you want to make sure yours is a safe situation, installed correctly by someone who knew what he was doing.
--

-MIKE-

"Playing is not something I do at night, it's my function in life"
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If it has a clock, or any type of electronic control panel, the oven circuit is still drawing power.

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On Thu, 11 Jul 2013 12:38:45 +0000 (UTC), Doug Miller

One other consideration depending on the age of the house was they used to allow the ground on an oven to serve as the nuetral for the stove. If there is a problem with the stove and there are bare grounds in a common box, however I wouldn't expect that with a 50 amp circuit but you never know. I to would first replace the GFI & see if it is the problem.
Mike M
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On Wed, 10 Jul 2013 23:36:35 -0700 (PDT), snipped-for-privacy@garagewoodworks.com wrote:

Replace the GFI device first.
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On 7/11/2013 10:25 AM, Markem wrote:

Absolutely the least expensive and easiest thing to start with when narrowing down the problem.
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On Wed, 10 Jul 2013 23:36:35 -0700 (PDT), snipped-for-privacy@garagewoodworks.com wrote:

I would agree that the first thing to do is to replace the GFI outlet. If that does not solve the problem, I would tighten the screws on the connections to these circuits in the panel box - especially the white (neutral) and ground wires. You may have a poor connection in that neutral in the box or even at one of the connections feeding the house from the power company's trasformer. Doesn't happen often but can cause all sorts of strange symptoms.
Gerry
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On Thursday, July 11, 2013 2:36:35 AM UTC-4, snipped-for-privacy@garagewoodworks.com wrot e:

ven light on. Now it's started to throw the same GFI at random times even when the oven is not in use.

t) the 110V GFI checks out 'correct' with the tester.

I swapped out the GFI and I still test 'bad' with outlet tester.
With the stove plugged in and circuit in 'off' position at breaker box the GFI tests normal (two right lights). When I leave the tester in the outlet and turn the breaker 'on' for the stove circuit the two right lights on te ster go dim and the left most light flickers. When stove is unplugged and I repeat there is no difference at tester when circuit is in 'on' or 'off' position at breaker.
This is a problem that has steadily worsened with the GFI tripping. I am v exed.
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snipped-for-privacy@garagewoodworks.com wrote in

I think it's time to call an electrician, Brian. The two circuits are cross-connected somehow -- possibly sharing a neutral -- and this is potentially *very* dangerous.
Leave the breaker for the stove off until this is resolved.
You're not anywhere near Indianapolis, right?
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On Thursday, July 11, 2013 12:32:54 PM UTC-4, Doug Miller wrote:

No. NC. I think you're right about the electrician. I'd hate to spend $80 bucks for him to tell me I need a new stove though. But I agree with you 100%.
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snipped-for-privacy@garagewoodworks.com wrote in

as paying him $80 to tell you that you *don't* have a problem in the *wiring*.
But I think he's going to find that you do.
In any event, once the problem is resolved, please follow up with a description of the cause.
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snipped-for-privacy@garagewoodworks.com wrote in

You'd hate it even more to spend a grand on a new stove, and find out that's not the problem after all.
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