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Three-Phase posted:
You freaked me out a bit since I install battery-backup solar electric systems with autotransformers so I looked this up; 210.9 "Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer." (I'll ignore the exceptions). Essentially, you can't run two hots without a neutral on either side of the autotransformer.
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Mar 20, 2009 20:57
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Elendil004 posted:There's no applicable codes this is in VT. Five seconds of googling gives me http://www.dps.state.vt.us/fire/licensing/Electrical.htm The 2008 NEC is the adopted electrical code.
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Apr 13, 2009 00:23
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grover posted:
On demand hot water heaters use less energy than a conventional electrical hot water heater since it doesn't have to keep a giant tank of water warm. But your flow is limited. Gas hot water heater is cheaper than both though. 
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Apr 15, 2009 02:35
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grover posted:Less energy, but FAR more power; don't confuse the two. Most definitely they are different. I think I misread what was going on. I thought he wanted to go to an electric hot water heater to save money.
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Apr 15, 2009 03:47
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Morkai posted:This little luxury wouldn't be about how fast the water gets hot for a shower, but to have an unending supply of hot water for 4 people to have showers without being rushed. Like you said they pull a lot of current, but less energy overall than doing a larger tank water heater, or two in series configuration. It also wouldn't be a large model, it only needs to feed the shower, not the whole house. Tankless hot water heaters don't work in a series configuration. Very few of them throttle the power, and the ones that do have a minimum power output. Because manufacturers don't ever want to put out scalding water, if the temperature coming in is too high (say 90F), the tankless hot water heater won't come on. Not only do you deal with luke warm water, you're susceptible to Legionellosis. A large tankless hot water heater at 3gpm can be fine for a house if you don't have multiple people using hot water at the same time. It all depends on preference and what you're willing to work it. Morkai posted:I'm all about planning. I've sized up everything I intend to do, and I think my 200A service will be just enough. I'm just undecided on if I like the idea of just enough, or if I want to have room for more if some other factor changes. For me personally, I'd want the room, but I don't think a potential buyer is going to think about a maxed out panel vs their future remodeling plans. What does it cost to go all out and hit 400A? Going over 200A isn't that easy. The feeder cables coming in may not be rated for over 200A and may have to be replaced. I've also heard of some utility companies requiring external disconnects for services over 200A. The cost depends on what area you're in. I've heard of service upgrades as cheap as $500 and go upwards of $3000. As always, get a quote, shop around, and make sure the electrican gets a permit. If you're doing it yourself, you'll need two 200A panels with a wire trough below. The feeder cables from the utility company go into the wire trough and branch off to the two panels. If you are doing this, GET A PERMIT so you can get a cut-in card for your utility company. They'll also come out and cut tag on your meter so you can remove it and not work on live wires. I wouldn't recommend do it yourself though. Morkai posted:I just want to augment the capabilities of my existing water heater, and only for the shower in the master bath. Given how well my water heater works, which is already electric and has a 2" added insulation blanket, I can go with one of the smaller 30-50A@120V on-demand types just to boost the temperature after the tank is depleted. I don't think they go that small. A Stiebel Eltron that'll raise water from 50F to 105F at 3gpm is 24kW.
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Apr 15, 2009 04:23
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Mthrboard posted:Quick question; does anyone here know if you are allowed to do an entire panel swap-out by yourself in Minnesota? I know we're allowed to do pretty much everything else in a residence, but I've read conflicting reports online as to whether replacing your main panel is allowed or not. My mom just bought a cabin by Itasca state park, and I want to upgrade from a 100 amp panel to a 200 amp, mainly so we can install a tankless water heater. I know what all is involved, and I believe I am up to the task, I just want to know whether or not I can actually do it legally. You'd have to go to your local building department to find out. They may require your mother to pull the permit unless your name is on the deed. You definitely need to pull a permit so you can get a cut-in card for the utility company. They need to check the feeder cables and/or transformer to make sure it's fine for a 200A service. IsaacNewton posted:I have this going from my house's 200 amp panel to my garage: (underground) Red and black are the two hots, the white is the neutral, and the green is the ground. I don't think direct burial comes in anything smaller than #6, so you're fine with a 60A breaker. There should be some writing on the outer insulation assuming it has not rubbed off that will tell you exactly what it is. IsaacNewton posted:Well I'm preparing to get a permit for this, hoping to have some help.. As grover said, you cannot feed a 70A subpanel with a 100A breaker. I'd recommend this instead. Type QO breakers are incredibly common.
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Jul 15, 2009 03:43
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Hillridge posted:I'm working on a design for a grid tied 5kW solar array I plan to install on my house. The inverter will need to be connected to my breaker panel via a backfed breaker. My house was built in the 70s and has those awful pushmatic breakers. I have plenty of 20A breakers open since the house was converted from electric to gas heat, but I think I'll need a 30 amp for the inverter. I hope you know what you're doing since installing a PV system is more complicated than most people think. Yes, you need a 30A breaker. However, if your panel is not rated at least 150A, it'll be a code violation. You can still get pushmatic breakers. Just not at home depot. You'll have to order online. All breakers are rated for backfeeding unless they specifically state line and load on them. There are other options - installing a subpanel from your main service panel. Or you can do a line side tap (although you would need a 60A breaker for that, and then a subpanel with the 30A breaker for inverter.) If you want, you could send me the design and I'll check it over for you. If you are connecting a grid-tied system, you'll have to file an interconnection agreement with your utility company.
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Mar 26, 2010 01:12
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Hillridge posted:Thanks for the advice. I'm not licensed. I design these things for a living though (NABCEP certified). You'll be fine with the GT 5.0. That's a pretty standard inverter, and a good one at that. The only issue I have with it is that the ground fault fuse is a pain in the rear end to get to compared to other inverters and it doesn't have a log of how many hours it's been up and running.
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Mar 30, 2010 01:49
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You'll probably want Suntech. They're good panels and one of the cheapest out there - Conergy has them. I'd try to stay away from Canadian solar since they're not that great. Yingli is new and they're pretty cheap, but I have zero experience with them. Here are some dealers you can look at. Sunwize DC Power Focused Energy Conergy USA If you have some issues with the dealers, altestore has some suntechs by the pallet that aren't priced too unreasonably. Xantrex's configuration tool is pretty good. Just remember to put in the record low for your area. Also, NEC 2005 and previous editions didn't recognize manufacturer's specifications for open circuit voltage calculations - you had to use a table. The NEC 2008 changed it and now requires you to use the manufacturer's specifications (this is how xantrex calculates it). Do you know what edition of the NEC is in effect in your area?
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Mar 31, 2010 04:30
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Unfortunately I just switched to a company that does large scale systems. I get truckloads of panels straight from distributors. If you're looking for US panels, you'll want Evergreen or Sharp (although technically sharp's cells are manufactured in Japan). Solon, REC, and Suntech are building plants in the US so panels can be assembled here, and they'll be Buy America compliant. Have you figured out which racking you're using?
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Apr 1, 2010 00:59
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According to their manual, it's rated for 160lbs. So in an aread with no snow and 90mph winds (average wind), it can do 32" OC spacing. That's pretty weak. It's also a shared rail system, so you have to lay it out perfectly, which isn't something I'd recommend for an inexperienced individual. I almost exclusively use Unirac. Their L-feet aren't ever breaking, and usually you can do 4' spacing on them. It doesn't have flashing, but using butyl tape on the underside, and around the head of the lag screw, and putting some sikaflex in the hole, you won't have any leakage. The company I use to work for has over 10,000 of these pentrations, and there were only had something like 10 calls for leaks.
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Apr 1, 2010 22:37
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tadashi posted:I just bought a foreclosed house that was remodeled in 2003 by a bunch of amateurs. That's the GEC. If that wire is removed, it can present a serious issue to your house. The odds of a plumber coming in and removing that section of the pipe is pretty small, but it shouldn't be too hard to fix. BTW, if it's the township electrical inspector, you must fix it since he's the one who pointed it out. I'm having a hard time making out the pic, but if it's a ground clamp, is there any reason why you can't move it? Or better yet, drive a new ground rod in and attach the GEC to that.
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Apr 1, 2010 22:53
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grover posted:Surge suppressors are OK because they're a loophole! Power strips and extension cords are only supposed to be used temporarily. IIRC, it's for less than 90 days and only during construction, or something stupid like that. I never thought of the code compliance of power strips before and it got me curious. So I did some looking. Power strips are to be listed to UL 1363. I didn't find anything in the NEC about Relocatable Power Taps (the closest is Article 380 - Multioutlet Assembly), so I have to go by the standards. According to that outline, they can be used for computer workstations and the like, but they can't be used in construction sites. Nor can they be daisy chained, or go through walls, or take the place of permanent wiring. So unless I'm missing something here, power strips are fine as long as they are used correctly.
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Apr 6, 2010 01:03
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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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If you can put a main breaker on your panel, you could use http://www.interlockkit.com/ Just be sure to use a holddown clip on your backfed breaker.
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May 1, 2010 16:53
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Hillridge posted:Does anyone know where I can get a cheap kWh meter (like what you would have on the outside of your house)? I'm building a solar array and want to put one between the output of my inverter and my main panel so I can keep track of my production. http://www.hialeahmeter.com/ They're utility grade.
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Jun 25, 2010 14:44
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Hillridge posted:Another solar related question: Only if you wire two poles in series can you get the 600VDC rating. Otherwise, each pole is only listed for 250VDC.
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Jun 27, 2010 14:51
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babyeatingpsychopath posted:Your ground must be in the same raceway as your current-carrying conductors. It can be solid or stranded, insulated or bare. If insulated, it must be green. The conduit has to be elevated a bit from the roof, or you'll create a dam.
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Jun 29, 2010 16:06
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babyeatingpsychopath posted:I have a whole bunch of those in a bag somewhere. Lemme see if I can find a better nomenclature than "those waterproof SO cord connectors." They're strain reliefs.
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Jul 9, 2010 14:57
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insta posted:Hmm, well, since there's apparently not a rule against it ... Technically, that's two code violations. One is not allowed to tape up wire that's smaller than #6, and a neutral is not allowed to be phased to hot. Someone some day might pick up that wire elsewhere and go "wow, that's white, it's a neutral! Let me splice in because it's a neutral...."
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Dec 18, 2010 18:32
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dwoloz posted:
Technically, you only need one ground rod if you can show that the resistance to ground is less than 40 Ohms. Otherwise, you need to sink another ground rod in a minimum of 6' away. However, it's far easier to to sink another ground rod and that's why a lot of inspectors will always say drive two ground rods.
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Sep 11, 2012 03:13
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