Surge

[John Dirks Jr]

Flip the disposal switch on and the kitchen and dining room lights surge really bright. It also happened every time the fridge compressor cycled on.

What is the likely cause of the surge?

[Marc]

Poor neutral connection. The neutral voltage is supposed to stay halfway between the 240v supply conductors, ideally 120 volt on each side. A solid connection to the main panel neutral bus holds it there. If it's a poor connection then the neutral voltage might creep to create a 130/110 division or perhaps a 125/115 division depending on how imbalanced the current draws are on either side and on how poor the neutral connection is. The disposer and fridge have low surge currents so I think most of the issue in your case is a poor neutral connection to the main panel neutral bus

If the lights were on the same side of the neutral as the appliances then the bulbs would dim instead.

Marc

[John Dirks Jr]

Thanks for the response Marc. Here's another question for you or anyone else who wants to respond. Obviously the cable in the picture is wrong do to the radius of the bend being too tight. Can this be fixed by simply straightening the cable or once it's over bent, should it be replaced? Of course, assuming enough slack were available you could cut it and splice it in a junction box and be considered correct as far as installation standards are concerned. But I'm not sure that's any better than just leaving it the way it is.

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[Marc]

It isn't worth writing up unless there's many more examples of such carelessness.

If I see that in my home, I straighten it out...with my hands.

Marc

[John Dirks Jr]

It isn't worth writing up unless there's many more examples of such carelessness.

If I see that in my home, I straighten it out...with my hands.

Marc

I could have straightened it out in that attic at the inspection. Would you have done that?

[Marc]

Not at all.

Marc

[John Kogel]

Right, the copper could snap if you played with it. I think I would leave it as is even in my own attic. But the temptation to straighten it could win out if I saw it enough times. []

[Marc]

I've bent the stuff hundreds of times during the course of wiring a new construction. It doesn't snap.

It's probably a manufacturer installation requirement that a minimum bend-radius be observed.

Marc

[kurt]

Yeah, I don't think one can snap copper without working it like crazy. Some reasonably gentle tweezing on that radius would straighten it out OK, but I'd not bother.

[rjbrown2]

I understand bends like that can slow the current down from about 0.9 the speed of light to about 0.8....

The cyclic bending associated with manufacturing and installation is so mild that the EC copper would almost never be work hardened enough to fail on the rebend. But, I would leave it alone too...

[John Kogel]

Yeah, I don't think one can snap copper without working it like crazy. Some reasonably gentle tweezing on that radius would straighten it out OK, but I'd not bother.

I just tried this 3 times, so this is not just guessing and not working it like crazy either. []

- Bend a bare piece of solid #14 copper in a tight loop and kink it in a tight hairpin with a pair of Linesman pliers. You have to use the right tool for this, because it is scientific testing. []

Straighten the kink out, and then bend it again in the same spot. When you go to straighten it a second time, the wire snaps.

[Marc]

Yeah, I don't think one can snap copper without working it like crazy. Some reasonably gentle tweezing on that radius would straighten it out OK, but I'd not bother.

I just tried this 3 times, so this is not just guessing and not working it like crazy either. []

- Bend a bare piece of solid #14 copper in a tight loop and kink it in a tight hairpin with a pair of Linesman pliers. You have to use the right tool for this, because it is scientific testing. []

Straighten the kink out, and then bend it again in the same spot. When you go to straighten it a second time, the wire snaps.

Jeez John, what are you trying to prove?

Marc

[John Kogel]

Yeah, I don't think one can snap copper without working it like crazy. Some reasonably gentle tweezing on that radius would straighten it out OK, but I'd not bother.

I just tried this 3 times, so this is not just guessing and not working it like crazy either. []

- Bend a bare piece of solid #14 copper in a tight loop and kink it in a tight hairpin with a pair of Linesman pliers. You have to use the right tool for this, because it is scientific testing. []

Straighten the kink out, and then bend it again in the same spot. When you go to straighten it a second time, the wire snaps.

Jeez John, what are you trying to prove?

Marc

I did prove that a kinked copper wire is easy to snap.[:-graduat

[kurt]

Let's see..... Bare wire, not insulated....check. Linesman pliers bending in a tight kink....check. Working it specifically to make it snap....check. Crazy anal retentive HI intent on proving a point....check.

I just got out of the basement from mangling some #14 NMC, bending, stomping, twisting....no snap. Took some #14 THHN, did the same thing, no snap.

There seems to be a discrepancy in our results.

[John Kogel]

Crazy anal retentive HI intent on proving a point....check.

I just got out of the basement from mangling some #14 NMC, bending, stomping, twisting....no snap. Took some #14 THHN, did the same thing, no snap.

There seems to be a discrepancy in our results.

if I was the sensitive type, I would be offended by all that.

The grounding wire in that kinked cable is not insulated. So it is the weakest wire in the cable and most likely to snap first.

Since we already established that an inspector ought to leave kinked wiring alone, I thought I'd add some test results. Which is what you read as being anal. [:-slaphap

There is a discrepancy in results simply because your testing did not follow the guidelines of my testing. We never did establish how many foot-pounds of tension to inflict upon the kinked cable, because there is no way to determine what was done there before we discovered the kink.

My point is this - if the kink is acute, the bare grounding wire could snap, so leave it alone. We don't need to hear how many times somebody has straightened a bent wire, or how many times he rode a bike without a helmet. []

[John Dirks Jr]

How many of you have replaced receptacles where the conductors are wrapped around the screws and had conductors break? I've had the conductors break on me many times. Then you have to strip and re-bend around screws.

A mild bend wont hurt the solid core copper. Even repeated mild bending probably wont. Start bending it tight, it's different ball game.

[kurt]

No one that's overly sensitive would stay around here for more than a few posts. It's the beauty of the place.

"We don't need to hear how many times somebody has straightened a bent wire, or how many times he rode a bike without a helmet."

Similarly, no one needs to hear about how one can take a piece of wire, subject it to ridiculous "tests", and then make claims that are equally ridiculous.

Of course one can snap a wire if they put their mind to it and develop "tests" to fit a predetermined result, but for chrissakes, is there no end to taking stuff to ridiculous conclusions in this biz?

No, there is no end.

[John Kogel]

My point is simply this - how tight can the wire be bent before it is too tight to straighten it?

Can't answer that without more testing.

OK I'm done here. Lock it up. []

[Jim Katen]

I'm actually quite curious about this. Just to annoy Kurt, try it again, but with these parameters:

Use #12 copper NM cable with the jacket still on it.

Produce a knot or kink in it like the kind that you'd get from pulling on a coil of cable without unwinding it. Pull it really hard, but only use your hands - no tools. Try to mimic the stress that might occur if an enthusiastic apprentice were to pull the cable until the kink hit a hole in a top plate or stud.

Then unbend it with reasonable care.

Now, remove the insulation and look at the conductors under a loupe to see if there's any visible damage.

I think that would mimic a real world scenario pretty well and tell us more about the likelihood of damage in these situations.

Bonus points: Try it again with solid aluminum cable.

[Erby]

Almost all y'all need to get a job to have something better to do!

[kurt]

I'm actually quite curious about this. Just to annoy Kurt, try it again....

That's the spirit. I was worried when so few felt compelled to pursue conflict.

Already tried aluminum. Working in a manner I thought reasonably mimicked a mildly competent tradesman, I wrapped some #12 around my needle nose in a loop about the size one would wrap a recep post. it's surprisingly resilient. Of course it was strained after 3-4 twists, but not bad.

Copper, #14, you can work that stuff. I presume we've all wrapped at least a few thousand posts with #14. I'm sure I've busted a few wires, but damn few, and I'm sure they were done when I was fiddling with the umpteenth iteration of a repair or otherwise behaving like a cretinous moron.

We've inherited wondrous metallurgical material unimaginable to previous generations and are so wimpy we imagine that by working something a few times, it's going to disintegrate. Ok. We live in dangerous times.

I am now old enough to actually know something about this thing we do, and have knowledge about things such as bending wires and hitting one's head without a bicycle helmet, and the likely effects that ensue.

Which is to say I've achieved complete irrelevancy, a fact oddly comforting to me.

[Jim Baird]

"...Sometimes nuthin' is a pretty cool hand to have..."---Lucas Jackson

[John Kogel]

This is the www, and people come here to learn, so I am sharing my observations.

If you stress a piece of wire, any wire, it develops little cracks. We all know this already.

Here in Canada, we use 15 amp circuits and #14 copper for most residential wiring, so that is why I tested #14.

I am not trying to prove I'm right in the normal anal sense, because if the wire did not break after folding it and unfolding it twice, I would have said so.

[mlparham]

I'm actually quite curious about this. Just to annoy Kurt, try it again, but with these parameters:

Use #12 copper NM cable with the jacket still on it.

Produce a knot or kink in it like the kind that you'd get from pulling on a coil of cable without unwinding it. Pull it really hard, but only use your hands - no tools. Try to mimic the stress that might occur if an enthusiastic apprentice were to pull the cable until the kink hit a hole in a top plate or stud.

Then unbend it with reasonable care.

Now, remove the insulation and look at the conductors under a loupe to see if there's any visible damage.

I think that would mimic a real world scenario pretty well and tell us more about the likelihood of damage in these situations.

Bonus points: Try it again with solid aluminum cable.

Now repeat the test 200 hundred times. Then you might have some results that could be evaluated.

[Jim Katen]

I'm actually quite curious about this. Just to annoy Kurt, try it again, but with these parameters:

Use #12 copper NM cable with the jacket still on it.

Produce a knot or kink in it like the kind that you'd get from pulling on a coil of cable without unwinding it. Pull it really hard, but only use your hands - no tools. Try to mimic the stress that might occur if an enthusiastic apprentice were to pull the cable until the kink hit a hole in a top plate or stud.

Then unbend it with reasonable care.

Now, remove the insulation and look at the conductors under a loupe to see if there's any visible damage.

I think that would mimic a real world scenario pretty well and tell us more about the likelihood of damage in these situations.

Bonus points: Try it again with solid aluminum cable.

Now repeat the test 200 hundred times. Then you might have some results that could be evaluated.

Good point.