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kid sinister posted:I'm looking at the 2011 book right now, and one entry on that table has the revision shading... I don't use aluminum and have probably done 1 or 2 jobs with a service that large out of hundreds. :p The only stuff I do that has services like that are hospitals, but I've never built one from the ground up, only done renovations to existing ones. You've motivated me though, I'm printing out a new cheatsheet right now.
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Jan 17, 2013 22:09
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I don't have my codebook handy. Does that table for grounding also apply to installations over 600V?kid sinister posted:Insta was recommending to use that a 5V DC wallwart as the signalling voltage to control the relays. 5 volts DC is kind of a standard for electronics. drat near everything uses 5V DC, down to USB connections. If you're talking about control relays (not like the tiny ones soldered onto circuit boards), usually the minimum voltage for the coil is 24VDC, at least that's what I've seen. This is coming from a more industrial-oriented standpoint. I'm personally a fan of 24VDC for controlling relays and logic, but a lot of places just straight-up use 120Vac. Three-Phase fucked around with this message at 09:15 on Jan 18, 2013 |
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Jan 18, 2013 09:11
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Three-Phase posted:I don't have my codebook handy. Does that table for grounding also apply to installations over 600V? I don't see any indications that would indicate otherwise in the section, so I would think it does.
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Jan 18, 2013 16:44
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Three-Phase posted:I don't have my codebook handy. Does that table for grounding also apply to installations over 600V? That's a good point. The ice cube relay selection pages in my catalog have columns for 12VDC, 24VDC, 24VAC, 120VAC, and 240VAC coils, all with 600V contacts at various (1-10) amperages. That's an industrial control catalog, and all those plug into socket bases. Over on mouser, however, there are piles of relays with <6VDC coils, but all seem to be through-hole.
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Jan 18, 2013 16:45
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You can get surface mount and plug-in relays from Mouser too, just not as many plug-in ones. Try digikey too. Anything under 12V is generally considered a "logic level relay" iirc; many have low coil currents so they can be driven directly by some families of digital logic ICs so their switching terminals can be used to control a larger relay or a small load.
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Jan 18, 2013 17:11
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babyeatingpsychopath posted:That's a good point. The ice cube relay selection pages in my catalog have columns for 12VDC, 24VDC, 24VAC, 120VAC, and 240VAC coils, all with 600V contacts at various (1-10) amperages. That's an industrial control catalog, and all those plug into socket bases. You can also get some in 120VDC. Those are a bit less common. I've seen a lot of 120VDC for the control power system for things like medium voltage circuit breakers. (Operating the coils that close and trip a 13800V, 1200A vacuum-bottle circuit breaker. Not too big, about the size of a washing machine.)
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Jan 18, 2013 22:51
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I want to add an outlet to my unfinished basement. There is a run nearby, and it is a 15A circuit with just a couple lightbulbs on it. I was planning on using the grey plastic tubing for conduit and coming into a two gang box. Does it matter if I use the plastic or metal for the conduit and the box? Do I screw the box into the masonry or is it supported by the clamps on the conduit?
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Jan 21, 2013 17:26
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XmasGiftFromWife posted:I want to add an outlet to my unfinished basement. There is a run nearby, and it is a 15A circuit with just a couple lightbulbs on it. I was planning on using the grey plastic tubing for conduit and coming into a two gang box. By "gray plastic tubing" do you mean PVC conduit or something else? The box must always be secured to the wall. There are only rare circumstances where you're allowed to conduit-suspend boxes. If you use all plastic, you just need to get your ground wire to your outlet device. If you use any metal, then that metal must be bonded to the ground as well. If you have plastic conduit and a metal box, you're going to need a grounding pigtail (ground screw + short piece of wire) to attach the ground to the box and the outlet. Final disclaimers: The outlet is required to be GFCI now. Make sure you've got a constant hot in your lighting run, or you'll be resetting the GFCI every time you turn the lights off.
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Jan 21, 2013 18:40
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babyeatingpsychopath posted:By "gray plastic tubing" do you mean PVC conduit or something else? Yes pvc, wasn't sure if it was pvc or some other plastic. Is there a reason to use metal over plastic? Ground wire is there so no problem. By constant hot do you mean have the circuits in parallel such that the light switch is 'downstream' from the outlet?
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Jan 21, 2013 18:55
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XmasGiftFromWife posted:Yes pvc, wasn't sure if it was pvc or some other plastic. Is there a reason to use metal over plastic? Ground wire is there so no problem. There are several types of "gray plastic conduit" out there. Some are flexible, some are liquid-tight, some have holes in them. Metal is more resistant to damage, and can be bent easily to conform to the path the conduit needs to take. It can also take paint well, makes it obvious when a wiring error has occurred (by tripping a breaker), and is generally longer-lasting. Plastic is cheaper and uses cheaper fittings, doesn't rust, doesn't require grounding connections, and can't shock you if you wired something up wrong. Constant hot means that when the lights are off, there's still a wire inside the box that has power on it. This depends on how your wiring is run, and is not usually obvious by casual inspection at one box in residential settings. A non-contact voltage tester makes the problem trivial. Open the box. Shove the beep stick inside, see it blink/hear it beep. Turn the lights off. If the beeping stops, no constant hot in that box (probably).
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Jan 21, 2013 19:49
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My Mom is currently in a 1950's house that needs some upgrades that I'm working on for her. She's currently got the two-prong outlets throughout. I'm wondering what the cost would be to just have a professional come in and properly convert all the outlets to the grounded 3-prong ones. My original plan was to install some GFCI outlets, but now I'm not sure if it's just better off long-term to bite the bullet and dish out some more money to have it done fully. While I know costs can vary, is this something that would be a few grand or something that would be $20k? I guess I feel torn between whether this is a DIY thing or something I should be forking over money to have done for her.
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Jan 21, 2013 23:52
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Niwrad posted:My Mom is currently in a 1950's house that needs some upgrades that I'm working on for her. She's currently got the two-prong outlets throughout. I'm wondering what the cost would be to just have a professional come in and properly convert all the outlets to the grounded 3-prong ones. My original plan was to install some GFCI outlets, but now I'm not sure if it's just better off long-term to bite the bullet and dish out some more money to have it done fully. For a remodel, most places around here will quote $100/outlet including material. They're betting that at their labor cost of $50/hr, they can get two outlets installed and grounded in an hour. For almost all outlets in the house, this is going to take five minutes per outlet, with only one or two taking an hour each. They're also assuming you're not at home and that they can turn the power off to the house for the whole time they're working. Other localities, especially old knob-and-tube areas, areas with crawlspaces, areas where all outlets are run with #14 aluminum, etc, may have different estimates, but they're all going to be based on the number of outlets in your house, if the estimator is any good. There are really crappy estimators that will tell you a job is going to cost $200 when they didn't notice half the outlets in the house, then they're going to whine that you're costing them money, do half a job, and leave. When taking bids, throw out the bottom bid and the top bid (usually). Pick the bid of the guy you liked the best from any of the rest.
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Jan 22, 2013 01:03
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Niwrad posted:My Mom is currently in a 1950's house that needs some upgrades that I'm working on for her. She's currently got the two-prong outlets throughout. I'm wondering what the cost would be to just have a professional come in and properly convert all the outlets to the grounded 3-prong ones. My original plan was to install some GFCI outlets, but now I'm not sure if it's just better off long-term to bite the bullet and dish out some more money to have it done fully. I wrote out a 3 prong upgrade post linked in the OP. My own house was built in 1956 and only had to run new cable for a few runs to upgrade to 3 prongs. It took me about a week for 800 ft2, but I did some other upgrades too like splitting up some existing circuits.
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Jan 22, 2013 01:21
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It really depends how accessible the outlets and panel are to fishing in new cable- you're paying for labor, and that's where the labor is. Call up some local electricians and get estimates. Or, you can always go the ungrounded-GFCI route which is relatively inexpensive and will make the house a LOT safer.
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Jan 22, 2013 02:54
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kid sinister posted:I wrote out a 3 prong upgrade post linked in the OP. My own house was built in 1956 and only had to run new cable for a few runs to upgrade to 3 prongs. It took me about a week for 800 ft2, but I did some other upgrades too like splitting up some existing circuits. I did see that and it was very informative. To be totally honest, I just feel intimidated taking that task on myself. The GFCI stuff I think I can do (and might do this weekend in some outlets), but the other stuff I feel more comfortable with someone experienced in it. YOu mention you had a 50's house, did you have to upgrade from 60amp to 100amp? Thank you all for your answers. From what I'm gathering this doesn't sound like a 5-figure job or anything. I believe she's got around 30 outlets in the house. There is a crawlspace and attic. The walls are plaster so I don't know if that means a bigger headache or not.
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Jan 22, 2013 04:19
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Niwrad posted:I did see that and it was very informative. To be totally honest, I just feel intimidated taking that task on myself. The GFCI stuff I think I can do (and might do this weekend in some outlets), but the other stuff I feel more comfortable with someone experienced in it. YOu mention you had a 50's house, did you have to upgrade from 60amp to 100amp? That really depends on what kind of condition the plaster is in, and what it's mounted on. If her house is just a concrete block house with plaster spread on, then it's going to be a shitload tougher. I'm talking all your walls too. If the interior ones are regular 2x4 stud construction but the exterior walls are masonry with furring strips, then those will be tougher to run cable in (be there, done that). And yes, the service was upgraded to 100A, but the previous owner took care of that. kid sinister fucked around with this message at 05:47 on Jan 22, 2013 |
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Jan 22, 2013 05:19
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I have a fan that I'd like to control with a footswitch designed for Christmas lights. The switch is rated for 500 watts incandescent load and I know electric motors are different but my fan only draws ~50 watts so a 10:1 safety margin should be more than adequate, right? More troublingly (possibly), when I run my microwave the lights get brighter, not dimmer. My Kill-a-Watt on a different circuit went from ~115volts resting up to ~125v with the microwave running then back down to ~115v. What the gently caress?
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Jan 22, 2013 07:38
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I'd almost put money on a floating neutral problem in your case. What's happening is the microwave is on the opposite hot leg, so when it draws a big load from that leg, the result of the somewhat-floating neutral is that the neutral voltage gets "dragged" further towards the other leg, which being 180 degrees out of phase with the one you're measuring, results in an apparent voltage increase on the lamp you're checking.
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Jan 22, 2013 08:04
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SlayVus posted:Could a bad UPS cause the constant problems? Like it's seeing the electricity is on then starts to draw, but causes a brown out on that breaker without actually tripping it? We call an electrician to come out, ended up being like a $200 bill. Basically, ALL the breakers on the outside breaker box had wiggled themselves loose some how and had gotten f'd up because of it.
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Jan 22, 2013 18:39
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Cat Hatter posted:I have a fan that I'd like to control with a footswitch designed for Christmas lights. The switch is rated for 500 watts incandescent load and I know electric motors are different but my fan only draws ~50 watts so a 10:1 safety margin should be more than adequate, right? I would recommend calling an electrician to look at it as soon as possible.
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Jan 22, 2013 23:02
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grover posted:It really depends how accessible the outlets and panel are to fishing in new cable- you're paying for labor, and that's where the labor is. Call up some local electricians and get estimates. Or, you can always go the ungrounded-GFCI route which is relatively inexpensive and will make the house a LOT safer. I only know what I"ve learned from my house so far (well and a degree in E.E. but that doesn't mean poo poo for house wiring) and I happened to just upgrade an outlet to 3-prong over the weeked. I've got old armored cabling (no ground, ground is the armor) and just wired the ground to a screw in the metal outlet box. How legit is this? I've seen it done in a few places around the house and assumed it was ok. Is Niwrad implying that it's actually just two wires running everywhere and ground wires need to be fished through?
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Jan 23, 2013 05:01
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I don't know if that's legal now on new construction, and modern BX/MC has ground wire in it anyways, but back in the day when BX/MC was common in residential construction, that's actually how they did it. My parents house was a horrible hodgepodge of knob and tube and BX/MC up till me and my dad redid the whole first floor with 12ga NM-C so everything would actually be grounded and properly polarized. The second floor is still a mess as far as I know. Sometimes you'll get lucky and the knob/tube won't actually have any knobs or tubes inside the wall itself, just in the floor joists and where they go up into the wall, so you can use one of the old wires to fish the new romex in. If there's a knob or tube in the way obviously this gets shot right to hell in a hurry. kastein fucked around with this message at 05:12 on Jan 23, 2013 |
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Jan 23, 2013 05:10
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kastein posted:If there's a knob or tube in the way obviously this gets shot right to hell in a hurry.
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Jan 23, 2013 19:57
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asdf32 posted:I only know what I"ve learned from my house so far (well and a degree in E.E. but that doesn't mean poo poo for house wiring) and I happened to just upgrade an outlet to 3-prong over the weeked. I've got old armored cabling (no ground, ground is the armor) and just wired the ground to a screw in the metal outlet box. How legit is this? I've seen it done in a few places around the house and assumed it was ok. Using AC is still legal for grounds in old installs. I'd check to see that your AC is still bonded to the panel at some point with a ohmmeter between the neutral and ground of your plug. That' wont tell you the impedance of your ground path, but hopefully it's low enough to pop a breaker. In a lot of older installs, yeah, there are precisely two wires going to outlets. In much older installs, there's only one. I remodeled a house from the 1880s that had the hot going into the bathroom light fixture with the neutral coming out of the fixture and going to the hot water pipe. One replaced water heater without proper bonding later, and you had to be pretty careful how you turned on the shower if the lights were on. When everything was installed, none of this was against code, because the electrical code hadn't been invented yet. Subsequent "updates" never touched the bathrooms, and nothing was ever noticed until a hundred years later, when modern electrical theory noticed some problems. Residential wire installs use the shortest, easiest path. If that drops down from the attic then goes horizontal for a bit until it hits a device, just remember that it was easy and cheap to INSTALL, and nobody cares one whit for future upgrades, except electricians. When we build our houses, the electrics are awesome and updatable and cost four times as much in material, but we don't care, since we're doing our own labor, which is "free" to us.
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Jan 23, 2013 21:38
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Cat Hatter posted:When I run my microwave the lights get brighter, not dimmer. My Kill-a-Watt on a different circuit went from ~115volts resting up to ~125v with the microwave running then back down to ~115v. What the gently caress? I found 2 neutral wires in my panel that looked corroded where they bond to the neutral bar and have some discolored insulation for an inch or two, could this be the cause of my weird voltage problems? Can I cut off the damaged wire and then wirenut a new piece on to make up the length or would I need to do that in a junction box outside the panel? Each circuit has the neutral and ground wire held under the same screw on the bus, is this legal?
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Jan 23, 2013 22:30
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Discolored insulation may likely mean overheating of the conductor. A poor connection or overloading can cause this.
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Jan 23, 2013 23:41
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So after months wondering about being over-capacity towards the end of this year and wanting to upgrade to 3-phase, I just realized my building already has it  Right now we have one main panel with a fairly inefficient circuit breaker layout, and a 60A branch to another panel that turns out to have most of the load in the building. I started to realize this after the breaker that feeds the second panel failed and not only did my server racks lose power, but lights went out in half the building  . Right now both panels are located right next to each other, with a massive conduit connecting them. I'd like to spread out the breakers, put my heavier loads on the main panel and the lights and crap on the secondary panel. Can I stay up to code by extending the wires inside the main breaker panel to reach through the connecting conduit to connect to breakers inside that aux panel?
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Jan 25, 2013 00:01
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dietcokefiend posted:So after months wondering about being over-capacity towards the end of this year and wanting to upgrade to 3-phase, I just realized my building already has it It depends, see NEC 312.8 for the requirements you have to meet to be allowed to splice the branch circuits inside the panel enclosure. If you do determine that you meet 312.8, the issue with running them through the existing conduit is that you would have to de-rate the 60A wiring per Table 310.15(B)(3)(a). If the panels are right next to each other, it would be better to just install a gutter between the two and run all of the branch circuits through there.
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Jan 25, 2013 01:04
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Oh god... My grandpa, God rest his soul, should have never been allowed anywhere near electricity. I'm fixing up their place to sell it, and in about 18 inches wide of wall space in their master bathroom, I counted 13 code violations. Knockouts without clamps, clipping off the ground despite it being available, chipping out drywall to run non-listed cable around studs then spackling over it, you name it. Did I mention that he raised 5 children in this house?
kid sinister fucked around with this message at 04:29 on Jan 25, 2013 |
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Jan 25, 2013 04:26
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I seem to be having trouble with the breaker in my living room, or rather, one of the outlets running to it. We first noticed problems when we plugged in the vacuum; most of the time it would be fine, but there would be instances of prolonged use that would trip the breaker at random. My initial thought was that the power may have acrced across, as one of the prongs of the vacuum was bent, and the cord head itself had started to wiggle its way out of the socket. To be more careful, I straightened the cord prong and tried again. The trip seems to happen less often, but all it takes is a little wiggle of the cord head and the breaker trips again. I've wondered if it was a problem with the outlet itself. Regardless, I've since then made a habit of plugging the vac in at the kitchen outlet, and never seem to have a problem there. But now I'm confused all over again, as last night the breaker tripped without any vacuum interference. That didn't make any sense to me. On a whim, I checked the living room outlet where I usually plug in the vacuum; I have an old 1920s radio over in that corner, and had recently plugged it back in. I had not turned it on in two days. However, I was surprised to find that the plug was warm, at this same outlet that has given me grief since we moved in. I know some modern electronics can have their plug become warm due to their standby nature, but this is an old vacuum tube radio: off is off, right? I feel like there could be a few things going on here, and perhaps several incidents of coincidence, but I obviously don't know enough about electricity to make the call. I know there's a lot plugged in the living room (entertainment center, electric fireplace, etc), but it's been acting just fine unless something is plugged in to that trouble outlet. Based on what I'm describing here, should I be looking at the outlet for issues, the breaker, or something else? I realize there may be more information needed to figure this out, so please, ask away and I'll do my best to provide it.
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Jan 25, 2013 21:42
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If there is heat at the outlet then there is a problem at the outlet. Start there. You probably fooled yourself into thinking it was related to the vac and its very unlikely that has anything to to with it.
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Jan 25, 2013 22:04
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Breakers have trip curves; they don't necessarily trip immediately if they're overloaded. The higher they're overloaded, the faster they'll trip, but they might run in overload for up to 10 minutes before tripping if it's only a slight overload, or may never trip at all. Vacuum tubes need to stay warm to work. That radio might actually be on all the time. Do you have a meter or something you can use to check it? You might want to check the outlet, too, and make sure it hasn't been damaged.
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Jan 25, 2013 22:24
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Doubt they're on all the time, that would severely impact tube filament lifespan. It sounds to me like a bad/loose outlet or wire on the back of the outlet... is the circuit fed with a regular breaker, a GFCI breaker, or an AFCI breaker?
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Jan 25, 2013 22:47
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It's on a regular breaker. Just came home to check the previously mentioned outlet, and was alarmed to find it warm to the touch without anything plugged in. The heater on the electric fireplace has been in use on an outlet on the other side of the room; based on what the internet is telling me, the warmth on the unused outlet is an indication that there's something loose inside, and that the additional electrical draw of the heater has revealed this. Should I just tighten up the connections inside that outlet, or also outright replace the outlet?
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Jan 26, 2013 04:25
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You're killing the power to the circuit & opening up the box anyway, I would just replace the outlet while you're at it.
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Jan 26, 2013 04:29
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EDIT: Forgot about how residential outlets are wired in parallel. So that would explain how the outlet had heat with no load plugged into it. If you do kill power and open it up (first, confirm that you killed power before doing any work!), you can touch or even gently tug on where the wires connect to the outlet. If there's a wire around a bolt or a backstab you can easily pull out, congratulations, you've likely found the problem. Look for any discoloration or worse, charring. If you smell anything odd, that could be important as well. If any of this gives you pause, simply turn off the circuit at the breaker and call an electrician. Three-Phase fucked around with this message at 04:43 on Jan 26, 2013 |
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Jan 26, 2013 04:37
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Three-Phase posted:Grover - could there be something like an intermittent high-impedance fault like arcing inside the box? A high impedance series fault doesn't trip breakers, though. I suspect two unrelated issues here- a fault in this outlet, and an unrelated overload causing the tripping breakers. What all else is plugged into this circuit? What turns off when the breaker trips?
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Jan 26, 2013 04:42
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I think I agree. But there's something else here I missed when I read this the first time: Something worth noting is that one of the appliances was a vacuum cleaner - a vacuum cleaner that probably has a little induction motor in it. For a resistive load like a heater, if you reduce the voltage, you'll porportionally reduce the current - Ohm's law. For an induction motor, if you decrease the voltage, the current draw will increase. The motor's power factor will lag, and you'll be putting in more current to do less real work. Depending on the design of the motor, a ten percent reduction in voltage means a ten percent increase in current. More than ten percent and the current can start to sharply increase. So if you had a bad connection in there, that would drop the voltage to the motor, cause the motor to draw even more current (despite the bad connection limiting the current to a small extent) and then the breaker would trip. My guess is that the kitchen outlet doesn't have this problem, and the current draw from the motor is well under the trip curve of the breaker. FUN FACTS: As far as the trip curve goes, the circuit breaker has a thermal element and a magnetic element. The magnetic element trips INSTANTLY once a certain large amount of current is passed, in a short circuit. Like for a 20A breaker that might be 400A for less than a sixtieth of a second. There's also a little strip, like in a thermostat, that trips if the breaker is exposed to a lower current for too long - an overload. Like Grover said, the lower the current, the longer to trip - like this for a 20A breaker: 16A (80% rating) - never trip 25A - trip after one hour at 25A 40A - trip after one minute at 35A 100A - trip after one second at 100A The delays allow for intermittent overloading and the massive current inrush associated with things like energizing motors and transformers. (These are gross approximations of points on the overload section of a trip curve.) This PDF from Schneider gives a good example of a trip curve. The long part at the bottom that's less than 1 cycle in duration is for the short-circuit pickup (ANSI 50). The long curvy part is the inverse-time current curve (ANSI 51). Fuses are also typically built with an overload element (like a spring clip) and a short-circuit element (all these little sections that vaporize in a short circuit). On the equipment I use at work, we have relays - nowadays these are little industrial computers that monitor the current flow indirectly (with a current transformer for 50/51 protection) and signal for much larger breakers to open. Three-Phase fucked around with this message at 05:10 on Jan 26, 2013 |
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Jan 26, 2013 04:52
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You definitely need to : 1) Turn the power off to the receptacle. 2) VERIFY THAT THE POWER IS OFF 3) Pull the receptacle from the box and check the connections. This really sounds like a loose connection at the receptacle to me. (next sentence is personal opinion) I wouldn't be surprised if you find the receptacle to be of the "back-stabbed" type. If that's the case and the connectiones are loose, replace the receptacle. If it's wired using the screws, you should be able to tighten it, assuming there's no noticable damage. For a couple bucks, I'd probably reaplace it anyway.
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Jan 26, 2013 11:54
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| # ? May 11, 2024 17:51 |
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Check this post out: Wrong ways to wire an outlet It's easy to make a crappy connection here.
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Jan 26, 2013 14:15
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