Conventional Fixtures HELP! Source 4 sparks at yoke

[Mac Hosehead]

lol, I remember split bolts. You had to tape 'em up good.

I have a story about swapped neutrals and grounds oddly occurring in Oakland as well. I was called out to a church auditorium with the complaint that some of the dimmer curves were strange and someone saw a big blue arc inside of one of the Sensor racks. No breakers were tripping. Further inspection onsite revealed that half of the neutral circuits were landed on the ground bus. The existing rack recently had circuits added to it and no one familiar with the equipment had checked their work. Good or sad, I never got to see the blue arc.

 

[almorton]

Electricity takes the path of least resistance.

This a fallacy that needs to be corrected. Electricity takes all paths available. The paths (note, plural) of least resistance will carry the most current, but all paths available will carry some current.

 

[BillConnerFASTC]

Electricity takes all paths available in inverse proportion to the impedance of the paths. If a path offers infinite impedance, like an insulator, it won't carry any current.

 

[almorton]

Exactly so, Bill. A path of infinite impedance, is (effectively) a path that is not available. All other paths, of non infinite impedance, are available, and the current flowing in that path will be distributed in inverse proportion to the impedance of the various paths (see also mesh analysis).

The impedance (or resistance) of a 5kW lantern is low. If you bridge that lantern with your fingers, there will still be a current flowing through you, even though the lantern is a much much lower resistance. The idea that electricity takes *the* path of least resistance, as if there's only one, has to be corrected, is all I'm saying.

 

[BillConnerFASTC]

You're making a semantic argument re: "available path" and the subtlety of a path of infinite impedance not being an "available" path so I'll just say that the statement that "electricity takes the path of least resistance" is indeed correct. This might not be the only path but the statement does not say it is, and thus is not false.

 

[almorton]

Have it your own way, so long as nobody is under the fallacious illusion that the path of least resistance is one exclusive branch of a mesh, and that the path of least resistance is, indeed, any and all conductive paths.

 

[Malabaristo]

Have it your own way, so long as nobody is under the fallacious illusion that the path of least resistance is one exclusive branch of a mesh, and that the path of least resistance is, indeed, any and all conductive paths.

I feel like the people who know enough to be able to estimate the relative impedance of various potential conductors are also likely to already know that it's not just "the path" of least resistance. For everyone else, that statement just translates to: "Electricity wants to kill you. Don't touch."

 

[BillConnerFASTC]

Like how did those electricians - experienced when I was young - know that if there feet were dry and they were not touching metal that the current would flow just through their adjacent fingers, and not up their arm and to their shoes, giving their heart a little jolt? Did they measure the impedance? And if they put one finger on the hot before the other on the neutral - the wrong way - would it still not flow through their body?

I never had the courage to try it myself. About best I can do is test a 9 volt battery on my tongue.

 

[Jay Ashworth]

Simple; if you're not sure it's hot/how hot it is, test with the *back of your knuckle*.

If there's current, it will contract your muscles, pulling the finger (and the arm) away from the electricity.

Or just bring a damn Wiggy.

 

[BillConnerFASTC]

I think the idea is it goes through just you hand. Don't give it a chance to go through heart.

 

[Jay Ashworth]

A separate rule, yes; always work on unknown or known-live circuits with one hand in your pocket.

("And the other one givin' a peace sign!")

 

[Ben Stiegler]

Ezra - what did the electricians find?