OT: Electrical

[Leon]

Absolutely the least expensive and easiest thing to start with when narrowing down the problem.

[Leon]

Don't laugh, did you test with your TS plugged in and running? I would want to eliminate the possibility of the circuit being used being the problem.

[brian]

ted 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.

l three lights on but dim. When I unplug the oven (on the dedicated 220V c ircuit) the 110V GFI checks out 'correct' with the tester.

old) has a component that has gone belly up.

x 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 tester go dim and the left most light flickers. When stove is unplugge d and I repeat there is no difference at tester when circuit is in 'on' or 'off' position at breaker.

I'd have to swap out the plug on the saw to fit the 50A 220V receptacle. M ight be worth the trouble.

[Scott Lurndal]

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

[Leon]

I think it will certainly tell you if it is the wiring or the oven.

[-MIKE-]

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.

[Bill]

Good idea!!! : )

[brian]

UPDATE:

I found one loose neutral on the neutral bus bar that I tightened down. Still I was reading incorrect w/ the three light tester (TLT for here).

I found a GFI I installed a while back (dedictaed circuit) that had broken free of the dry wall. The plastic fins broke off apparently from an extension cord pull.

I replaced the two plastic fins and anchored down again. So far I am reading correct on the "faulty" gfi and the oven is plugged in w/ light on.

Lets see if she trips the gfi.

I inspected the receptacle that came loose from the drywall for signs of arching and I saw none. Looked clean.

-BG

[Martin Eastburn]

One never really knows, might be a loose screw in the main circuit box. When the stove draws current it might be putting some current on the ground (safety) line. That would dump a GFI.

Mart> 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.

[Lew Hodgett]

---------------------------------------------------------------------------------- Does the stove/oven have a 3 Pin (L1, L2, G)or 4 Pin (L1, L2, N, G) plug?

A 3 Pin (L1, L2, G) plug indicates that any 120V loads are being fed by on leg (L1 or L2) and ground (G).

A 4 Pin (L1, L2, N, G) plug indicates that any 120V loads are being fed by on leg (L1 or L2) and neutral (N).

Either of these will generate an unbalanced load that may be significant enough to trip a GFI receptacle depending on how the circuitry in the house is wired.

The 3 Pin will be a tougher problem to chase down.

You indicate that if the stove/oven is unplugged, the GFI doesn't trip.

If that is true, the stove/oven could be the problem, especially if there is a loose connection someplace in the stove/oven or back at the panel.

Good luck.

Lew

[Doug Miller]

"Lew Hodgett" wrote in news:51df7c6c$0$1210$c3e8da3 $ [e-mail]:

Only if the GFI is on one leg of the 240V circuit -- which it clearly is not, since in the original post Brian described the GFI functioning normally when the stove breaker was turned off.

[Doug Miller]

"Mike Marlow" wrote in news:kro0al$qq5$1@dont- email.me:

Improperly-made connection eventually opened up. One possibility is a loose wire nut somewhere on the neutral conductor for the circuit the GFI is on.

Another possibility is a mouse making contact between two conductors (don't scoff, I've seen that happen).

Something strange is going on here, which is why I advised Brian to get an electrician out ASAP. Tough to try to diagnose this from 800 miles away. Somebody needs hands-on.

[Doug Miller]

"Mike Marlow" wrote in news:krpe59$n9$1@dont- email.me:

Sure it could. Loose wire nut falls off, connection comes apart, neutral conductor comes in contact with an equipment grounding conductor.

Not very likely, I'll grant. But it's still a possible scenario.

[Doug Miller]

[e-mail] wrote in news: [e-mail]:

Not all three-light testers are the same; it would help to know if yours is the same as mine:

Assuming that it is, then this pattern of lights means that you have hot current on both the ground and the neutral.

If you don't have a voltmeter, get one. The Harbor Freight $2.99 multimeter is actually a pretty decent piece of gear.

Then do these tests:

1. Unplug the stove, turn the breaker for the stove circuit ON, and turn the breaker for the GFI outlet OFF. Measure voltage between hot and neutral, hot and ground, and neutral and ground at the GFI outlet. All three readings should be zero (or possibly a small fraction of

1V). Plug your tester into the outlet. All three lights should be off. If you read voltage here, or if the tester lights up, STOP, call an electrician.

1. Check voltage at the stove receptacle: hot1 to hot2 (240V expected), hot1 to neutral (120V), hot1 to ground (120V), hot2 to neutral (120V), hot2 to ground (120V), neutral to ground (zero). [If the stove has a three-wire plug, omit the hot to neutral tests.]

2. Turn the stove breaker OFF, and the outlet breaker ON. Repeat the voltage measurements at the stove receptacle. All voltages should be zero.

1. Repeat the voltage measurements at the GFI. Hot to neutral and hot to ground should be

120V, neutral to ground should be zero.

1. With the stove still unplugged, measure the resistance between the two hot prongs on the stove plug. I think you'll see something between 5 and 10 ohms.

2. Measure the resistance between each hot prong and the ground prong on the plug. If it's a 4-wire plug, repeat for hot to neutral. Let me know what you get for these measurements.

[Doug Miller]

"Mike Marlow" wrote in news:krpine$q2q$1@dont- email.me:

Whatever it is, it's got to be something strange. No possible fault in the stove could be causing stray voltage on a completely separate 120V circuit -- therefore the two circuits are not completely separate.

[clare]

5 to 10 ohms across L1 to L2? That would be a 25 amp load with everything shut off. I don't think so!!! Between hots there should be virtually infinite resistance. Between one line and neutral/ground you should see better than 50 ohms - ideally closer to 500 ohms - which is the clock / controller load. With the oven door open that should drop to 220 ohms or less (40 watt 120 volt). Turn on any element and the line to line should drop to something less than 20 ohms.

[clare]

We still don't know if the stove and gfci circuit are on a sub-panel. I suspect they are.

[Swingman]

That was my first thought ... but I usually stay out of wRec electrical threads.

[hubops]

Yep. John T.

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[Mike M]

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