Home |
Search |
Today's Posts |
|
Home Repair (alt.home.repair) For all homeowners and DIYers with many experienced tradesmen. Solve your toughest home fix-it problems. |
Reply |
|
|
LinkBack | Thread Tools | Display Modes |
#42
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
Mark Lloyd writes:
I was studying digital electronics in college, but did once take an elective course in NEC. I remember getting one test question "wrong", in one of those cases where you get penalized for knowing something you aren't expected to. The question was about a 3-phase wye-connected motor, and asked True or False: the current in each leg is the same. The supposed "correct" answer was True, although I knew that was impossible. One of things they taught in electronics was that the sum of the currents in a node is always zero (electrons are flowing FROM somewhere TO somewhere). The currents could never be equal unless they were all zero. They were asking about time-averaged current of some sort, probably RMS current, while you were thinking in terms of instantaneous current. That's sort of like being asked a question on a high school physics test about the validity of Newton's laws when you already know about relativity. *You* know that Newton's laws are not always valid, but at the same time you should be able to figure out that *in the context of the physics class*, they are. Dave |
#43
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
You also might want to be sure anyone else who's around knows what you're doing, and won't turn that breaker back on. True, true. But if you have insulated tools the only times you mgith actually have contact is when you are doing "preliminary" wire twisting or are handling things like switches our outlets. You can strip and bend and twist wires without touching them directly. |
#44
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
On Sun, 21 Oct 2007 05:10:19 +0000 (UTC), (Dave
Martindale) wrote: Mark Lloyd writes: I was studying digital electronics in college, but did once take an elective course in NEC. I remember getting one test question "wrong", in one of those cases where you get penalized for knowing something you aren't expected to. The question was about a 3-phase wye-connected motor, and asked True or False: the current in each leg is the same. The supposed "correct" answer was True, although I knew that was impossible. One of things they taught in electronics was that the sum of the currents in a node is always zero (electrons are flowing FROM somewhere TO somewhere). The currents could never be equal unless they were all zero. They were asking about time-averaged current of some sort, probably RMS current, while you were thinking in terms of instantaneous current. At one particular time, you would see different voltages (and could figure out the current would be different). You could not see phase without seeing more than a singe instant. That's sort of like being asked a question on a high school physics test about the validity of Newton's laws when you already know about relativity. *You* know that Newton's laws are not always valid, but at the same time you should be able to figure out that *in the context of the physics class*, they are. There's many cases where honesty is NOT the best action. I often get into trouble for that reason. Dave -- 65 days until the winter solstice celebration Mark Lloyd http://notstupid.laughingsquid.com "Unlike biological evolution. 'intelligent design' is not a genuine scientific theory and, therefore, has no place in the curriculum of our nation's public school classes." -- Ted Kennedy |
#45
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
On Sun, 21 Oct 2007 08:36:33 -0400, "John Gilmer"
wrote: You also might want to be sure anyone else who's around knows what you're doing, and won't turn that breaker back on. True, true. But if you have insulated tools the only times you mgith actually have contact is when you are doing "preliminary" wire twisting or are handling things like switches our outlets. You can strip and bend and twist wires without touching them directly. And try to never touch more than one at a time. Of course perfection doesn't exist and there's no way you can guarantee no mistakes. BTW, I once touched a hot (120VAC) wire while replacing a switch, and felt nothing at all. -- 65 days until the winter solstice celebration Mark Lloyd http://notstupid.laughingsquid.com "Unlike biological evolution. 'intelligent design' is not a genuine scientific theory and, therefore, has no place in the curriculum of our nation's public school classes." -- Ted Kennedy |
#46
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
On Oct 18, 7:39 pm, "Proch" wrote:
I recently began a project where I built a shelf and moved lots of my computer stuff under the floor and into my basement. Part of it was a mount a power strip with a 15' extension cord onto the ceiling and then use those U shaped nails to neatly get the cord to the electrical socket. I spent a whole day doing it and when I was done, everything was great - except that when I turned off the basement light, the battery backup started beeping. The electric socket is switched... There are two flat cables leading into the socket (which is mounted on the ceiling) and one that comes out. This one goes to a light. That light does NOT go on or off with the switch. It's my intention to open the box and rewire it to not be switched. Before I cut the power, can anyone give me an idea of what I'll see when I open it, and what the best way will be to make it not turn off when the switch is thrown. Maybe one line just happens to pass under the switch, and all I'll have to do is switch between the outlet and the light (I wouldn't mind if the light were switched...) Thanks is u r google broken u sad pathetic loser social reject |
#47
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
Mark Lloyd writes:
They were asking about time-averaged current of some sort, probably RMS current, while you were thinking in terms of instantaneous current. At one particular time, you would see different voltages (and could figure out the current would be different). You could not see phase without seeing more than a singe instant. By "instantaneous current", I really meant "instantaneous current as a function of time". If you look at the phase currents with an oscilloscope, you can see that there is a phase shift between phases, so the current waveforms are not equal. The question was asking about average current as a scalar, not vector, quantity. There's many cases where honesty is NOT the best action. I often get into trouble for that reason. Or more generally, providing the "full" answer to a question when the asker only wanted the quick one-sentence executive summary. Most people just want an answer, they don't want to understand the reason behind the answer. I'm one of the people who always wants to know where the answer came from, and how approximate the answer is, but I seem to be in a distinct minority. Dave |
#48
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
On Mon, 22 Oct 2007 20:33:34 +0000 (UTC), (Dave
Martindale) wrote: Mark Lloyd writes: They were asking about time-averaged current of some sort, probably RMS current, while you were thinking in terms of instantaneous current. At one particular time, you would see different voltages (and could figure out the current would be different). You could not see phase without seeing more than a singe instant. By "instantaneous current", I really meant "instantaneous current as a function of time". If you look at the phase currents with an oscilloscope, you can see that there is a phase shift between phases, so the current waveforms are not equal. The question was asking about average current as a scalar, not vector, quantity. And a "scaler" is a "vector" with some information ignored. In that situation, I did not know just what information was supposed to be ignored. There's many cases where honesty is NOT the best action. I often get into trouble for that reason. Or more generally, providing the "full" answer to a question when the asker only wanted the quick one-sentence executive summary. One that's wrong. Most people just want an answer, they don't want to understand the reason behind the answer. That seems to be true. This mental laziness contributes to a lot of problems. Things are much easier to understand when you know what's going on. I'm one of the people who always wants to know where the answer came from, and how approximate the answer is, but I seem to be in a distinct minority. And there's nothing wrong with that, as in the quote on my homepage '"I was almost normal once, but then I got better.". Simplistic, but generally true. Dave -- 64 days until the winter solstice celebration Mark Lloyd http://notstupid.laughingsquid.com "Unlike biological evolution. 'intelligent design' is not a genuine scientific theory and, therefore, has no place in the curriculum of our nation's public school classes." -- Ted Kennedy |
#49
Posted to alt.home.repair
|
|||
|
|||
CONCLUSION: Electrical Outlet Wiring
Today I found he time to complete this task. The unswitched light and the
switched socket were on two different circuits. I identified and turned of these circuits. Once I removed both the light and socket from their mounts, the wiring in both cases was very simple. All I did was switch the light and socket with their mounts and all is well. Thanks for all the input. Somehow I expected the switched outlet wiring to be much more complicated, but instead the whole circuit is switched. "Proch" wrote in message . .. I recently began a project where I built a shelf and moved lots of my computer stuff under the floor and into my basement. Part of it was a mount a power strip with a 15' extension cord onto the ceiling and then use those U shaped nails to neatly get the cord to the electrical socket. I spent a whole day doing it and when I was done, everything was great - except that when I turned off the basement light, the battery backup started beeping. The electric socket is switched... There are two flat cables leading into the socket (which is mounted on the ceiling) and one that comes out. This one goes to a light. That light does NOT go on or off with the switch. It's my intention to open the box and rewire it to not be switched. Before I cut the power, can anyone give me an idea of what I'll see when I open it, and what the best way will be to make it not turn off when the switch is thrown. Maybe one line just happens to pass under the switch, and all I'll have to do is switch between the outlet and the light (I wouldn't mind if the light were switched...) Thanks |
#50
Posted to alt.home.repair
|
|||
|
|||
Electrical Outlet Wiring
On Oct 19, 12:47 pm, Jeff Wisnia wrote:
Proch wrote: I recently began a project where I built a shelf and moved lots of my computer stuff under the floor and into my basement. Part of it was a mount a power strip with a 15' extension cord onto the ceiling and then use those U shaped nails to neatly get the cord to the electrical socket. What you just said you did (Nailing an extension cord) is quite likely in violation of the electrical code in your area. Now that you've told the world what you did here with a post that may be findable 'forever' I suggest you check the code and if needed change the installation to be code compliant, even if it means having to hire a licensed electrician to do it if DIY electrical work isn't permitted in your area. I realize there's a slim chance that tacking up that cord created a serious fire hazard, but if G-d forbid there should be an electrical fire in that area of your home, maybe caused by one of the pieces of computer gear deciding to flare up, your insurer may do their best to get out of paying if they can find evidence that you did something which was not to code. Peace, and don't take this personally, Jeff -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) The speed of light is 1.8*10^12 furlongs per fortnight. snipped re "Now that you've told the world what you did here with a post that may be findable 'forever' I suggest you check the code and if needed change the installation to be code compliant..." Or at least re-post and *tell* us that you changed it. ;-) |
Reply |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Wiring Electrical outlet | Home Repair | |||
FS Six 20A outlet shop electrical panel, each outlet protected | Woodworking | |||
FS Six 20A outlet shop electrical panel, each outlet protected | Metalworking | |||
FS Six 20A outlet shop electrical panel, each outlet protected | Woodworking | |||
FS Six 20A outlet shop electrical panel, each outlet protected | Home Repair |