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Richard Noggin posted:As I was removing the outlet covers before painting my bathroom, I found that one of the blank covers was hiding some wiring that was not used. The ends were cut off clean, but there are no wire nuts protecting the ends. I can't imagine that this was up to code. I found my tester today; the line is dead. No idea what it's for.
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Apr 17, 2010 22:25
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grover posted:Per APC, all their Smart-UPS series draw exactly 1A of battery recharge current, regardless of size. Well, at least they did about 5 years ago when I last spoke to their engineers about it. That is impossible. Just switching my Smart-UPS 1000 to test where it shifts load to battery for 5 seconds makes it spike at the wall above 1A. Maybe trickle never goes above 1A or something?
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Apr 19, 2010 03:48
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dietcokefiend posted:That is impossible. Just switching my Smart-UPS 1000 to test where it shifts load to battery for 5 seconds makes it spike at the wall above 1A. Maybe trickle never goes above 1A or something? It doesn't make logical sense either, since that means for example that the 375kW battery bank I specified for the last data center I did would take 450 hours to charge. 15 minutes of battery backup isn't very useful if you have to charge the batteries for 18 days between events. How it actually works on high-end UPS's is there is an adjustable setting that allows you to set the battery recharge current anywhere from 0 to 25% of the maximum battery discharge current, with 15% being the typical factory setting.
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Apr 19, 2010 18:08
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Papercut posted:It doesn't make logical sense either, since that means for example that the 375kW battery bank I specified for the last data center I did would take 450 hours to charge. 15 minutes of battery backup isn't very useful if you have to charge the batteries for 18 days between events. The spike after the self-test; was it actual battery recharge, or just a momentary spike of transformer magnetization current? I can't imagine 5 seconds of self-test requiring anything more than trickle charging. Most of the commercial UPS systems of 100kVA+ I've worked with have been set to 30% recharge current by default, but we like to set that to 10% to lessen thermal stress on the batteries during recharge. With 15 minute batteries, this increases recharge time from 45 minutes to a little over 2 hours, but the chance of back-to-back deep cycles where that hour faster recharge would have made a difference is next to nil. grover fucked around with this message at 13:33 on Apr 20, 2010 |
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Apr 20, 2010 13:30
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You said it was 1A regardless of UPS size, which is why it didn't make sense.
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Apr 20, 2010 16:06
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kid sinister posted:In other words, it has a feature that every GFCI receptacle has built in already. The button on the GFCI tester is useful for testing outlets daisy chained off the GFCI outlet, to make sure the GFCI outlet will trip when an outlet down the line faults, and also for testing outlets on GFCI breakers.
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Apr 21, 2010 04:46
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I'm looking for guidance on a relay switch to cut off power to my dehumidifier if the condensate pump fails. I'm working with this pump: http://www.lgpc.com/Product/ItemDetail.aspx?ProductID=843 The manual (located at http://www.lgpc.com/ProductFiles/OM/998086.pdf ) has this to say about the low-voltage lead which I have to work with: quote:Safety switch: The safety overflow switch should be connected Preferably I'd like to buy something that comes with one or two receptacles which would be switched off if the switch is signaling an overflow. I'm comfortable doing basic electrical and electronic work if necessary though.
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Apr 21, 2010 20:57
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I almost burned the house down. Well, rather, not I, but years of neglect and the fact that my landlord has a strict hands off approach to building maintenance. I was having trouble with nuisance tripping one one particular circuit, so I was going through disconnecting lines to see what was causing the trouble. When I disconnected this outlet, the problem went away, which was odd... because there was no load on it, it was behind the couch. Well, I decide to take a look at it, and when I pulled the box away from the wall, this is what I found:  Click here for the full 2048x1536 image. Definitely billing the landlord for this repair. E: Also, how much do you think I should bill them for replacing the box, outlet, and entire run back to the breaker, considering it's all cloth insulated wire. I only know IA rates, and seeing as this isn't a theatre I don't think they'd apply. corgski fucked around with this message at 23:10 on Apr 21, 2010 |
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Apr 21, 2010 22:43
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God knows how many more of those you have waiting to happen... I've had similar experiences, but with modern wiring - back-wired outlets that were sloppily installed. gently caress those things.
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Apr 21, 2010 22:58
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How many of you guys remember that scene from Christmas Vacation where the cat bites the christmas lights and sparks underneath that chair? This Christmas at my parents house I had the delight of checking out an outlet that kept having problems after one my my parents cats pissed on it. The night of the piss the thing shorted and smoked enough where the fire dept had to come to the house to check it out. After it dried out it didn't have problems... that is until some repair guys used the outlet to plug in a shopvac to clean up some debris from a window replacement. Insulators melted, kept tripping the breaker, etc etc. I came into town and was given the task of fixing the outlet since it was pretty funky. At the time that circuit also powered our christmas tree. I wanted to verify the circuit was working and stuff so I had my dad trip the breaker for a sec. Motherfucking shower of sparks shot out from the outlet, lit up the living room like the scene in Christmas Vacation as my sister and I screamed to my dad SHUT IT OFF SHUT IT OFF. Scariest poo poo I have seen in my life. One of the contacts fused and somehow after the breaker was turned back on didn't make it trip again to turn off. Half of the insulation was gone and I got to inspect lots of holes in the carpet from the molted plastic that went flying  Any ideas what went wrong? Not really with the outlet... but with the breaker that allowed a shorted outlet to continue shorting? I replaced the outlet and house hasn't burnt down yet in the past four months. Old wiring is cloth stuff so guessing knob and tube and the saving grace was the metal junction box that made the wall not burst into flames.
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Apr 22, 2010 00:45
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Our kitchen has two switches that control a light in the ceiling. For some reason it is wired so that both switches have to be on for the light to work, instead of each switch just toggling the light on or off. What do I need to do to have them working properly?
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Apr 22, 2010 04:25
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Associate Christ
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Need more information. Are both switches the three-way type, and do they have the extra conductor running between them? Usually red/black/white/ground in a single cable. If so, they might just be miswired. Here is a good set of diagrams: http://www.homeimprovementweb.com/information/how-to/three-way-switch.htm The common terminal is the differently colored one - it's not necessarily in the same place on every switch. slap me silly fucked around with this message at 04:40 on Apr 22, 2010 |
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Apr 22, 2010 04:37
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Mark Kidd posted:I'm looking for guidance on a relay switch to cut off power to my dehumidifier if the condensate pump fails. I'm working with this pump: http://www.lgpc.com/Product/ItemDetail.aspx?ProductID=843 I'm going to quote myself here and say that as I think this over a bit more, it seems clear that this safety switch is designed to work with electronic thermostats. Is someone familiar with thermostats well enough to know what voltage I should be working with and how the "COM and NO switch terminals" for a thermostat work so I can find a relay that will match those specs?
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Apr 22, 2010 14:43
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Kaluza-Klein posted:Our kitchen has two switches that control a light in the ceiling. For some reason it is wired so that both switches have to be on for the light to work, instead of each switch just toggling the light on or off. This sounds like instead of using 3-way switching, they used standard switches with no relay so that both switches have to be closed to complete the circuit. Seconding the post above mine, is there a red wire going between the switches?
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Apr 22, 2010 15:35
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Mark Kidd posted:I'm going to quote myself here and say that as I think this over a bit more, it seems clear that this safety switch is designed to work with electronic thermostats. When the float is low the state is NOT normal, the switch is pressed in, and COM is connected to NO (Normally Open). When the float goes high, the switch is released, the state is normal, and COM connects to NC (Normally Closed/Connected) Here is a tutorial on building a switched outlet that can be driven by a micro: http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=119 For your application though, we can simplify it. You will need a relay that can handle 15A @120V. The control voltage isn't important, but try to keep it under under 24V. If you get one that switches at 9V or less, you could run this off of a 9V battery. Otherwise you will need a DC power supply. I'll assume a 9V battery for ease of explaining. 1. Connect +9V to the COM terminal of the switch on the pump. 2. Connect the NC terminal on the switch to one side of the coil on the relay. 3. Connect the other side of the coil to the - terminal on the battery. 4. Wire up the outlet as shown in the link I posted, but use the NC contact on the relay, not the NO! I added that bold bit, because the sparkfun project is designed to turn ON an outlet when the relay is energized. You will want to turn OFF the outlet. When the float goes high, the switch will turn on the relay, which breaks the connection between COM and NC on the relay and kills power to the outlet. Hillridge fucked around with this message at 16:27 on Apr 22, 2010 |
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Apr 22, 2010 16:22
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Quick mspaint: Load1 is the black wire from the power source. Load2 is the black wire to the controlled outlet. The diode isn't essential, but is a good idea. Hillridge fucked around with this message at 16:37 on Apr 22, 2010 |
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Apr 22, 2010 16:34
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Hillridge posted:Quick mspaint: I think you've got the relay load contacts wired backwards. If the float is not normally high, then then NC will be on, so the relay will be on, so the contacts will be closed. You have NC on the relay controlling the load, so they'll be open if the float is down. Right? When the float goes up the power goes off? That means NO contacts on the relay control the power.
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Apr 22, 2010 16:47
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Our local permit office allows homeowners to do electrical work with a permit if they pass a test. According to the permit officer it's a 2 hour test that references the NEC. Can you guys recommend any study guides or resources I should consult to prep myself for the test?
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Apr 22, 2010 17:30
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babyeatingpsychopath posted:I think you've got the relay load contacts wired backwards. If the float is not normally high, then then NC will be on, so the relay will be on, so the contacts will be closed. You have NC on the relay controlling the load, so they'll be open if the float is down. That's the confusing bit. When the float goes up, the switch is released, so NC(sw) is shorted to COM(sw). This then energizes the coil, turning on the relay and breaking the connection between COM(relay) and NC(relay). you could reverse everything as well though, which may be safer. In one instance (the one I described), the relay is only powered when the float is high, so it saves power. The problem is that if your DC supply dies, the outlet will turn back on. The other way around wastes power but fails to outlet off.
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Apr 22, 2010 18:25
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babyeatingpsychopath posted:I think you've got the relay load contacts wired backwards. If the float is not normally high, then then NC will be on, so the relay will be on, so the contacts will be closed. You have NC on the relay controlling the load, so they'll be open if the float is down. So it seems like you can do this either way, right? Normally closed relay, we would connect the pump switch via the NC terminal and the COM terminal and when the float was high it would complete the control circuit between the battery and the relay coil, electrifying the coil and pull the high voltage paddle away, breaking the circuit and killing power to the receptacle. Pros: does not draw power from the battery Cons: does not fail if the float is high but the battery is dead Normally open relay, we could connect the pump switch via the NO terminal and the COM terminal, when the float is low the switch would complete the control circuit between the battery and the relay coil, pulling the high voltage paddle into place and allowing the receptacle to work. Pros: failure of the 9V power supply cuts off power to the dehumidifier Cons: always drawing 9V, can't use a battery Have I got this straight? Edit: Simultaneous posting. Hopefully we are speaking in the same terms.
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Apr 22, 2010 18:25
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Yeah, we're on the same page. I'd look for a SPDT relay (that one from spark fun is not a SPDT) since it will have both options and shouldn't cost any more than a SPST one. I'd say go with option 2. I don't like the idea of constantly wasting energy (roughly 1W with the relay from sparkfun), but I like things to fail safe. you may also be able to find a relay that consumes less power. A solid state relay would do it, but they cost a lot more. Hillridge fucked around with this message at 18:46 on Apr 22, 2010 |
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Apr 22, 2010 18:43
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Cool. I see something like this relay here: http://www.grainger.com/Grainger/items/1EHE3?cm_mmc=Google%20Base-_-Electrical-_-Relays-_-1EHE3 It's SPDT, 12VDC for the coil, rated for 10A inductive and 20A resistive. I would match this with a 12VDC 1A power supply and a 12V diode (connected between the coil on the relay and the - terminal on the power supply) and be good to go?
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Apr 22, 2010 19:03
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Mark Kidd posted:Cool. I'd use one of these relays from digikey: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PB308-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PB310-ND They are the same internals, just with different mounting and connector options, and a lot cheaper than the one you linked. They come in different voltages. Those two are 12V versions and only need 83mA of current to turn on. Use a 100mA supply just to be safe. A 1N4148 diode is super common, and for something like this you don't even really need it. If you have one laying around, use it, but I wouldn't buy one just for this.
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Apr 22, 2010 19:31
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Thanks for all the help. I've got my relay ordered and I'm looking forward to putting this together. Hopefully this is the ticket to keeping my basement nice and dry from here on out.
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Apr 22, 2010 20:45
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slap me silly posted:Need more information. Are both switches the three-way type, and do they have the extra conductor running between them? Usually red/black/white/ground in a single cable. If so, they might just be miswired. Here is a good set of diagrams: They are 3-way switches. One switch has red/white/black, with black being common, and the other has red/black/black, with one of the blacks being common. The 2nd switch's box also has a white wire with a cap on it, seemingly doing nothing. I don't have any sort of testing equipment.
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Apr 22, 2010 21:58
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dietcokefiend posted:
You don't have a Federal Pacific panel, do you? In any case, breakers do go bad after a few trips. It varies from manufacturer and from model number, but I was talking to a UL inspector who recommend that a breaker be replaced after five trips. I'd recommend replacing the breaker.
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Apr 23, 2010 23:36
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I am helping someone convert an existing in-wall outlet, into a surface-mount outlet so that we can tap off of it to run a second outlet. The existing (3 prong) outlet has no ground wire connected to the receptacle, so we reconnected the outlet, turned thr breaker back on, and I checked it with a multimeter to make sure that the junction box itself was grounded, and it is. Once the outlet is surface mounted though, I'm not sure how to ground it. The backing of the surface mount box will be connected to the box in the wall, but I don't know if this is actually enough of a connection. I thought about running a wire from the ground screw on the outlet to a ground screw I could put into the back of the existing box, but I bought a pack of ground screws and they aren't even close to fitting in either of the two holes in the back of the box. The holes aren't threaded anyway. So will it be enough that the surface mount box will be connected via screws to the in-wall box? I was worried that even if it does provide a connection, maybe the impedance wouldn't be low enough, but I really am not sure if this is a valid concern, and I know that I can test it with the multimeter but I'm unsure of how to do it exactly and don't want to screw anything up. Thanks!
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Apr 26, 2010 00:52
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Briantist posted:I am helping someone convert an existing in-wall outlet, into a surface-mount outlet so that we can tap off of it to run a second outlet. The ground screws you bought are self-tapping. If even a little bit fits into one of the holes, just go ahead and ram it in there, making a nice, solid, squished-threaded-mangled metal-to-metal connection. I don't think I'd trust the surface extension screws to provide an effective ground-fault current path.
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Apr 26, 2010 01:31
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babyeatingpsychopath posted:The ground screws you bought are self-tapping. If even a little bit fits into one of the holes, just go ahead and ram it in there, making a nice, solid, squished-threaded-mangled metal-to-metal connection. I don't think I'd trust the surface extension screws to provide an effective ground-fault current path. I thought about running the bare end of a ground wire into one of the holes and then putting the screw in and forcing it in there, again squishing the wire and screw against the box and each other. What do you think about that? Any other ideas? Thanks for the quick response. Edit: Actually I think I just figured out how to do it. The backing to the surface mount actually doesn't connect to the in-wall box it all; it screws into the wall separately, but it has notches cut out where the original outlet would have connected to the in-wall box, which allow a path for the original screws. I can connect the ground wire to those screws, which will be screwed directly into the in-wall box, and the other end of the wire will connect to the ground screw on the outlet. It's using the original screw that grounded the outlet in the first place so I think should be okay. Briantist fucked around with this message at 02:24 on Apr 26, 2010 |
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Apr 26, 2010 01:54
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I'm renovating an old condo that hasn't been touched in years. It's a small place, so I'm trying to avoid cluttering it with odds and ends which would make it feel smaller - to include the lighting fixtures. One idea I'm kicking around is to add recessed lighting around the periphery of the main living room, which would allow light to bathe the walls and make it feel a little more open and warm. BUT, the ceiling and walls are concrete ... so I can't just drill a hole in the ceiling and stick in a light canister. Here's one idea I've come up with (before and after shots) ... but I'm worried about heat dissipation. Any thoughts? I figure if I leave a gap between the ceiling and the "racetrack" that the lights would live in, I'd probably be alright (?).   Here's what I'm kinda going for: 
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Apr 26, 2010 11:20
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Kaluza-Klein posted:They are 3-way switches. Sorry to quote myself, but am I going to be stuck unless I have a volage meter?
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Apr 26, 2010 16:20
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Well, the safest thing is gonna be to trace each wire from outlet to outlet and outlet to light, but you could manage that with a battery, a flashlight bulb, and a long piece of wire.
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Apr 26, 2010 16:25
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Kaluza-Klein posted:Sorry to quote myself, but am I going to be stuck unless I have a volage meter? Not necessarily, you can get a circuit tester at any hardware store for under $2. 
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Apr 26, 2010 22:53
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OK, I think I just did something really stupid and I'm a little bit terrified right now. I just moved in to an old (1920's) house that has been split into apartments. The outlets are two prong, and I wanted to see if they could be changed out for grounded three-prong outlets. The electrical panel in the basement looks newer. I bought a circuit tester and put one end in the hot and the other end to the screw that holds the face plate on. Nothing. I took the face plate of and repeated but touched the other end to the metal case. Nothing. I thought I was out of luck, but the guy at home depot told me that often the metal flex conduit is grounded and to check that. Here's where it gets scary. I put one end in the hot side of the outlet, and poked the other end back towards where I could see the top of the flex conduit coming into the box. As I was doing this there was a big spark, and flash and some smoke. I jumped back and my heart was/is racing. Did I almost kill myself? Feel free to tell me how loving stupid I am. When I looked at the circuit tester, the end that I had tried to touch to the flex conduit was a bit charred and melted. Right now I'm too terrified to even put the face plate back on or use the circuit tester to see if there is power to the outlet. That outlet is on the same circuit at the refrigerator, so I don't want to just leave it off. So...what did I do? What do I do next? Wow...
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Apr 27, 2010 00:40
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Your probe tip touched the hot screw on the side of the outlet and the grounded conduit at the same time, maybe? Don't go poking around blindly around in a live box. Uh, next. If I guessed right then it's probably fine. Turn off the breaker, pull out the outlet (no need to disconnect the wires), and make sure all the wires and connections look ok.
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Apr 27, 2010 00:54
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I got this spot welder http://www.harborfreight.com/230-volt-spot-welder-45690.html years ago from someone off craigslist. The problem is, is that I do not have any 230v outlets near where I want to use my spot welder. How dangerous/difficult would it be to make a 230v extension cord from my washer outlet?
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Apr 30, 2010 17:44
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refresco posted:Here's where it gets scary. I put one end in the hot side of the outlet, and poked the other end back towards where I could see the top of the flex conduit coming into the box. As I was doing this there was a big spark, and flash and some smoke. I jumped back and my heart was/is racing. Did I almost kill myself? Feel free to tell me how loving stupid I am. When I looked at the circuit tester, the end that I had tried to touch to the flex conduit was a bit charred and melted. And no, you didn't "almost kill yourself", you just got a little careless and let one of your probes touch a hot wire AND a grounded wire at the same time, thus becoming a short circuit. The spark/bang was arc flash, and is quite dangerous in larger switchboards (especially big high voltage utility line stuff) where it's powerful enough to give 3rd degree burns and melt clothes to flesh, but not nearly so dangerous at the low energies typically found in homes. Still, it's a good reminder to all of us that proper protective equipment for working on wiring is gloves and safety glasses. If any of that metal that vaporized from the arc found its way into your eye, it'd be very painful. Don't be afraid to stick the probes back in the box- just BE CAREFUL, and never get complacent. One of our generator techs was recently killed- an experienced professional who works around high voltage and big components all the time, electrocuted at home working on his computer. Be safe, guys. grover fucked around with this message at 18:09 on Apr 30, 2010 |
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Apr 30, 2010 18:04
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GreenTrench posted:You don't have a Federal Pacific panel, do you? Interesting.... never knew that. I will have my dad check the panel. Its a grey panel, no cover, flush mount on the wall with exposed white/creme colored breaker switches. The switches had a smooth action almost like a normal light switch, not the CLUNK you get from a modern breaker. Also another fun one to make your brain hurt. Few years ago I had a Miller 210 MIG welder and was working on a car project. I started the project out in the driveway, well out of reach of the welder and my fancy outlet. Problem was I had to tack pieces together on the car or the stuff would never line up. To get those initial spot welds I opened up my mini breaker box in the garage, hard wired two 50 foot 18 gauge christmas tree light extension cords together (finger twisted in the middle for projection) and hard wired it into the welder. It worked but it wasnt pretty. 40A or so at 240V flowing through 100 feet of 18-gauge cheap christmas tree extension cords. Each time the welder was activated a puff of smoke lifted off the entire stretch. It was awesome  . By the time I was done the cord was hot to the touch and melted apart near the sliced in the middle where I had finger twisted the wire together. I think I ended up shopping 5 feet from each end and using that wire to replace some leads on an old 2 amp battery charger.
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Apr 30, 2010 18:46
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Wiring question: I replaced the kitchen light in our house. It seems that the previous owner ran some romex to a three-switch box, next to a dimmer switch. When I first hooked up the new light it didn't work. Took out the multimiter and was getting 120v when the hot and ground were connected, and nothing when the hot and neutral were connected. So I looked in the switch box and it appears that the neutrals for the light and the dimmer switch were wired together with the other ends wired to nothing. So I pigtailed the neutral from the light with neutrals from the other two light switches, then I got 120v from the hot and neutral wires. Then, tried the dimmer (never found what it was for until I did this) and it blew, so I just unwired it and capped off the hot and neutral dimmer wires and left them in the box. Is my house going to burn down? I have know idea how or who wired all of this but it definitely isn't all original. Also, there was no box for the light, they just ran some romex across the attic and used a board to attach the light to.
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Apr 30, 2010 19:21
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I'd like to come up with a better way of providing generator power to my house. My service comes into a 100A service disconnect (a single 100A breaker mounted so the switch flips up and down, instead of left and right) on one wall of the garage. That in turn is wired to the main panel, which is located on the opposite wall. Currently, when we have an extended outage, I flip the service disconnect and the main panel disconnect off, then backfeed the panel. I always make sure that both disconnects are in the off position before I do this. I really don't want to be limited to a few circuits with a standard transfer switch. What I'd like is a transfer switch that gets installed at the service disconnect location. That way, I can provide power to whatever circuit in the house I want. Do they make something like this? I don't need an automatic transfer switch; a manual one will be fine.
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Apr 30, 2010 20:35
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