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Landerig posted:
And just in case anyone is wondering, I will be fixing that. Just need to get an electrician to put in a sub-panel for me. The guys who replaced the pump wired everything correctly into a watertight pullbox; once the sub is in I will dig a new trench and run the wire correctly.
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Jun 3, 2011 20:18
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grover posted:The hard part will be running the ground conductor from your house. So, we decided that the homeowner is just going to hire an electrician for this, as it would be better to have it done right. But for learning purposes, I hope you don't mind me asking a few more questions! I'm confused on what the three wires in the box are, as your quote implies there is no ground. What are the big no. 2 wires connecting to the lugs on the pane?, I figured they were hot, ground, and neutral. And now that I'm looking at it, what is that left lug connected too? If he needs to run ground, the shed is pretty far away, so would driving a grounding rod be an option?
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Jun 4, 2011 02:48
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Low-Pass Filter posted:
Its really hard to tell from your pictures, and frankly probably impossible because they are unmarked. It could just be a case of improper bonding in a sub panel. The neutral and ground on the same bus bar. But they could also be running that large extra conductor to feed another neutral somewhere. It would really take being there in person to deal with this. The electrician will just run a new grounding conductor out to the box, separate the neutral and ground and either do a whole new box which wouldn't be that expensive or put some split breakers in to accommodate the new circuit. Anyway good luck. I have to do almost the same thing at my aunts house this weekend so my grandparents can run the AC in their motor home.
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Jun 4, 2011 04:38
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tworavens posted:Its really hard to tell from your pictures, and frankly probably impossible because they are unmarked. Look again at his second picture, it has the schematic of the all the bars as laid out in the box. That's two hots (solid black), a neutral (black with stripe), and no ground. It should be possible to just add a grounding busbar directly against the steel box and make sure it's separate from the neutral bar. The hardest part will be needing to run a No. 2 wire for ground. If you're lucky, that conduit line runs all the way to the house. If you're not, get ready to dig up the ground in between...
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Jun 4, 2011 19:17
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grover posted:There are certain cases where a larger or smaller neutral is prudent, but you're not using those kinds of loads. I think if you have a lot of harmonics (esp. zero-sequence harmonics), you can have problems with the neutral overheating unless it's oversized, but that's nothing a person will see in a home.
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Jun 4, 2011 20:54
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Low-Pass Filter posted:I'm confused on what the three wires in the box are, as your quote implies there is no ground. What are the big no. 2 wires connecting to the lugs on the pane?, I figured they were hot, ground, and neutral. And now that I'm looking at it, what is that left lug connected too? I'd advise driving a supplemental ground rod, but you still need to run an actual ground wire from the main panel. If you don't do the grounds right, you end up with the potential for a high-impedance fault where there is an arcing/sparking short circuit that can start a fire but not trip the breaker! Three-Phase posted:I think if you have a lot of harmonics (esp. zero-sequence harmonics), you can have problems with the neutral overheating unless it's oversized, but that's nothing a person will see in a home.
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Jun 4, 2011 21:58
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grover posted:but you still need to run an actual ground wire from the main panel. How does this work if the main panel has a bonded neutral/ground? What exactly are you attaching to what? If you ran ground to ground, you'd just be bonding the neutral bar and the ground on the sub panel as well, but through the main panel, no?
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Jun 6, 2011 15:49
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Quick question - if I have 2 circuits in a single box, do I need to attach the grounds from the 2 circuits together or insulate them from one another?
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Jun 6, 2011 17:01
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TouchyMcFeely posted:Quick question - if I have 2 circuits in a single box, do I need to attach the grounds from the 2 circuits together or insulate them from one another? Yep, twist the grounds together. Keep the neutrals separate though.
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Jun 6, 2011 18:49
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Thanks! Another quick question - If I am abandoning a section of wiring, do I need to hook the ground up on the end where it previously hooked up to the live circuit?
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Jun 6, 2011 19:16
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Motronic posted:How does this work if the main panel has a bonded neutral/ground? What exactly are you attaching to what? If you ran ground to ground, you'd just be bonding the neutral bar and the ground on the sub panel as well, but through the main panel, no? Yes and no. They will end up with slightly different potentials and you also have to handle the safety concern of allowing an easy way for current to flow down a ground wire that is labeled as if it is only a safety ground, not a neutral. It has to do with keeping things very well separated for safety. Think about how if you had ground and neutral bonded at your subpanel and at the main panel current would be equally liable to flow from the neutral connections in the subpanel through the ground cable to the main panel as it would be to use the proper neutral cable. It is improper and unsafe for a cable marked as ground to be carrying a neutral return current. You open up the possibility for this with a subpanel having neutral and ground bonded, thus you're only supposed to so that at the main panel. It gets more complex than this and someone who does this for a living, not just a hobby, can probably explain it better than me. It will function but it is improper. Edit for more explanation: People forget that electrical current flows somewhat like water being affected by gravity. You can have a series of pipes but putting water in one pipe doesn't mean it will instantly come out all other ends of the pipe. It will flow to the lowest point. Current will always take the best and easiest way to ground. This should be the neutral connection on your main service, which goes right back to the generator at the station. In a bonded setup the current leaving your house does not elect to flow into your grounding circuitry because the neutral back to the power company is a preferable route. This is why the answer to "arent you just bonding the ground and neutral at the sub panel through the main panel" is really no. Are they physically connected? Yes. But so is the sewer pipe on your toilet and on your neighbor's toilet..but his poo doesn't come flying out of yours. Normally. Edit again: TouchyMcFeely posted:Another quick question - If I am abandoning a section of wiring, do I need to hook the ground up on the end where it previously hooked up to the live circuit? Someone call me wrong on this one but I'd say unless you are removing the wire it is most safe to leave the ground connected. I dont believe you hurt anything by doing this and you ensure that, if somehow any idiot in the future does something dumb with that wiring (or some idiot before you spliced into it in a strange way) you arent cutting off your safety ground for ..what advantage? I dont see the harm in leaving it and it seems to open narrow but possible dangers having it ungrounded unless you totally tear it out. I am less sure about this answer than my previous one, though. Havent had to deal with this. Groverrrr chedemefedeme fucked around with this message at 04:21 on Jun 7, 2011 |
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Jun 6, 2011 21:16
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The neutral bus must be bonded to ground once and exactly once in the system. If it's bonded more than once, what you end up with are parallel conductors, and neutral current flowing through the ground, which is dangerous. People don't often think of wires as resistors, but they are- any time current flows through a wire, you get voltage drop which means the neutral wire is never at 0V even though one end is grounded, it's at a few volts potential with respect to true ground, which creates a shock hazard- this is also why you don't want to use neutral as ground. (Throw a wrench on a car battery, and see what a few volts can do.) During fault conditions, voltage can raise much higher, too.TouchyMcFeely posted:Thanks!
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Jun 6, 2011 22:15
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grover posted:You're required to remove what's accessible, but if it's inaccessible, you're permitted by code to abandon it in place. I'd recommend grounding it for safety's sake, lest there be some short in the future that energizes it. Removing the wire in question would require removing the back splash and some dry wall to get to. I tried pulling it but I'm pretty sure it's nailed in place in a couple of spots. I put wire nuts on both ends of the neutral and hot legs and tagged each end with white electrical tape saying "Abandoned" with the date and where the other end terminates and both ends terminate in an accessible box. I'll go ahead and reattach the ground. Thanks for the clarification.
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Jun 6, 2011 23:24
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chedemefedeme posted:Think about how if you had ground and neutral bonded at your subpanel and at the main panel current would be equally liable to flow from the neutral connections in the subpanel through the ground cable to the main panel as it would be to use the proper neutral cable. grover posted:People don't often think of wires as resistors, YES. This is what I was missing in my thought process. Thank you both.
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Jun 7, 2011 03:12
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Hah, holy crap I was right both times. A really fine point made about wires being resistors. It is obvious and I even have to deal with it in my professional work in low voltage...but it really easy to forget sometimes how much this can factor in. We take for granted that electricity just makes it to the other end of a wire, but it just isnt as easy as that. To the electricians by trade..how often does this get done incorrectly? (seeing multiple neutral-to-ground bonding points in a system) Is it by incompetent electricians or homeowners installing the wrong panels and not removing the bonding bar? Have you ever seen damage done by it?
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Jun 7, 2011 04:21
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I need help, a friend of mine is planning on adding a garage on to the side of their house in the country without a permit  - so this means they'll be using a contractor that is willing to work without a permit. That in itself bugs me based on the holmes on homes shows I've seen, but what really worries me is that they'll be building the garage so that the outside electrical junction is enclosed on the inside of this "garage", as pictured here: So how bad is that? Also, the power to the junction is underground, which will be under the concrete pad that they are pouring this week
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Jun 7, 2011 06:34
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Well for one, I suspect that the electrical company will poo poo a brick come time to access the meter for any reason.
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Jun 7, 2011 06:37
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yeah they won't like that at all. might refuse to continue giving him power until he moves it. probably will call the permit office on him too. Edit: I would recommend to your friend that he have a licensed electrical contractor move the meter to the side of the house. Most pocos are okay with meter placement being somewhere on the front 3/4's of the building. That is to say the two sides closer to the road and the side facing the road. Putting a concrete pad over it probably won't matter, but different areas have different codes for that because its a power company dictated thing. After that he can do whatever unpermitted work he wants with somewhat less fear. Personally I would question what kind of job a contractor who will work without permits is going to do. Anyway, I hope that doesn't all end in tears. But please update us if he goes ahead with this plan. I like hearing stories about crazy hack work. tworavens fucked around with this message at 07:15 on Jun 7, 2011 |
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Jun 7, 2011 06:47
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Just found this old picture from 2008 and figured I'd share. One day in the middle of summer the AC goes out in my dad's house. Lucky for me, we had two and I'm the only one living in the area served by this unit. Breaker panel isn't tripped so I grab a flashlight and pull the fuses.  : That's an odd looking fuse... The HVAC guy said that if there had been fuses instead of copper pipes in that holder they would have blown during the incident (probably a brown-out) that caused the trouble. Luckily for us, the compressor/important bits were fine because a light gauge wire had melted into nothingness before any real damage was done. The best part of this story is that this house was built in the late '90s and the only previous owner was the electrician who built it as his own personal house.
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Jun 7, 2011 08:57
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zantar: your friend can NOT do that! It is 100% unsafe, illegal, and will get his house condemned and power shut off if he tries it. If he wants that room to be there, he's going to need to move the meter.chedemefedeme posted:To the electricians by trade..how often does this get done incorrectly? (seeing multiple neutral-to-ground bonding points in a system) Is it by incompetent electricians or homeowners installing the wrong panels and not removing the bonding bar? Have you ever seen damage done by it?
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Jun 7, 2011 10:53
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Cat Hatter posted:
Wow. At what point didnt they realize the AC makers simply would have designed the thing without a fuse holder if it didnt NEED A FUSE. I've seen people like this. They just think "oh well you dont NEED one" and every time it blows my mind how they think companies, which are always looking for every corner to reduce prices when making a product, would have added the extra components and labor required for safety feature x if it was not important. If its a safety feature, and its on a commercial product, it was important enough that they reduced some profits putting it there so its probably pretty dang important! In other news, is that a freaking awesome lego jet plane?
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Jun 7, 2011 15:59
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Cat Hatter posted:
Correct me if I'm wrong, but shouldn't a house built only 15 years ago also have a double pole breaker for the AC compressor? Why didn't the breaker trip?
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Jun 7, 2011 17:17
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kid sinister posted:Correct me if I'm wrong, but shouldn't a house built only 15 years ago also have a double pole breaker for the AC compressor? Why didn't the breaker trip? It did have a double pole breaker and I'm not sure why it didn't trip but I'm not really sure why an air conditioner needs both fuses and a breaker. At least I now know first hand that they are both required. And yes, that is a freaking awesome lego F-14 with moving swing-wings that my girlfriend bought me (she's awesome too).
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Jun 7, 2011 18:08
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I've seen people do that, the guy probably didn't have any on hand and then just forgot to order the correct fuses. Not a good practice to say the least. In the home you could cause a bad fire or destroy the equipment it protects. What is really scary is when someone does this on a really high power circuit in an industrial setting. Good way to kill somebody.
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Jun 7, 2011 18:55
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Cat Hatter posted:It did have a double pole breaker and I'm not sure why it didn't trip but I'm not really sure why an air conditioner needs both fuses and a breaker. At least I now know first hand that they are both required. Otherwise, you could burn your house down if the compressor stalls.
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Jun 7, 2011 23:13
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Cat Hatter posted:It did have a double pole breaker and I'm not sure why it didn't trip but I'm not really sure why an air conditioner needs both fuses and a breaker. At least I now know first hand that they are both required. What NEC article is that in? Guess all the non-fused A/C disconnects are code violations.
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Jun 11, 2011 03:11
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So today I get a call from my buddy at work telling me his neighbors house was struck by lightning. The only visible thing damaged at first was an outlet that blew up and launched off a picture frame near it. They checked the wiring at that outlet, nothing charred... thought that was the worst of it. Got an email about an hour later "gently caress. the house is on fire" Lightning struck the roof, blasted apart a support, and followed a path along the wall with the blown outlet into the basement. All hidden damage until the fires built in strength. Lots of areas with small fires that just took over after a bit of a delay  . My buddy was over a second time to check on some things with the neighbor when the smoke started pouring out from everywhere and called 911. Short version of the story there is maybe 100k in damage but since they were home when it broke out everyone is safe, and its all structural damage.. nothing personal gone.Are newer construction homes more susceptible to lighting strikes than older homes? I was thinking about this for a bit... they don't have any metal running top to bottom like you might find in an older house. With PEX/CPVC plumbing there is no thick conduit for power to travel to from ground besides electrical and maybe wood. Would a lighting rod or lightning pegs spread across a roof line grounded into the yard have helped this situation?
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Jun 11, 2011 04:20
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Csixtyfour posted:What NEC article is that in? Guess all the non-fused A/C disconnects are code violations. I didn't mean to imply that all A/C units require fuses, either legally or for safety. In fact, the HVAC guy who replaced the burned wiring brought that up: "If he didn't want to use fuses, there are units designed to not need them". I'm not an electrical engineer but I usually assume that if something was designed and built with a fuse holder that it shouldn't be jumped with a big piece of metal just because other things are designed differently.
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Jun 11, 2011 05:03
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dietcokefiend posted:Got an email about an hour later "gently caress. the house is on fire" While I can't answer your later question I am very curious about the answer. I don't hear much about lightning protection but am in an area where once or twice a year the lightning coming down is just beyond intense. I've suffered emp damage to equipment in my home but never direct strike. I can say, however, that I've been called out to service low voltage wiring and equipment in a few homes that were direct struck. It is scary. Like..will amaze and creep you out as you find things days afterward. On more than one occasion I've pulled stuff off of our out of walls and found evidence of small fires smouldering for some time after the strike. If you are witness to a direct strike of your home or someone else's home do not assume the worst is over right then. Begin visiting every room and closet of the house, watching carefully for smoke and using your nose. As soon as the storm has passed get someone up in the attic asap to inspect up there. Sometimes a simple flashlight can help check for things. Be sure to check outlets behind cabinets and beds. One of the worst I've ever seen was a cat5/ethernet plate behind a dresser in a little girl's room. During the direct strike the plate, screws torn clear out of it, was blown off the wall and into pieces. The back of her dresser was charred as well as the insulation inside the wall being blackened. And to my greatest amazement....the cat5 cable's 8 little internal conductors were fused into one stiff rod of copper. It was like a metal pole in the wall and extremely hard to remove. It was black and melted stiff about 8 feet up the cable from the plate when I got it out. Holy crap.
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Jun 11, 2011 06:36
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Oh and one last thing to make you sleep easy. No smoke alarm went off. The one theory I have is in this area all smoke alarms must be on the same dedicated AC circuit. If lightning hit that line on the way through the house it could have fried them all. In some ways I am kind of liking the older battery only isolated units...
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Jun 11, 2011 06:58
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I don't see why not use both. I've seen a number of houses with ac powered alarms and one or two battery alarms also located near bedrooms and such. They cost pretty little, look unobtrusive and you can't be too safe. I'd love to hear anyone experienced chime in here on the importance or effectiveness of home lightning protection setups. We've talked about whole house surge protection in this thread but what about protection from direct/extreme proximity strikes?
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Jun 11, 2011 23:14
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chedemefedeme posted:I don't see why not use both. I've seen a number of houses with ac powered alarms and one or two battery alarms also located near bedrooms and such. They cost pretty little, look unobtrusive and you can't be too safe.
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Jun 12, 2011 01:32
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grover posted:There's very little you can do if there's a direct lightning strike: your house is fried. A properly grounded home electrical system will greatly reduce the likelihood of a lightning strike, though; it dissipates the ionization that attracts lightning.
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Jun 12, 2011 02:16
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grover posted:There's very little you can do if there's a direct lightning strike: your house is fried. A properly grounded home electrical system will greatly reduce the likelihood of a lightning strike, though; it dissipates the ionization that attracts lightning. http://www.intermatic.com/~/media/f...ta%20sheet.ashx  I have seen lighting rod ground conductor run on the inside of the wall, and terminated on the ground rod in the basement. Who the ever thought that was a good idea should be shot.
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Jun 12, 2011 02:31
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Csixtyfour posted:Intermatic sells a "lighting Arrester" FYI for others reading this: Actual lightning arresters used by the utilities work by different principals and work well to isolate lightning strikes by momentarily shutting off utility lines and causing brief losses of power that annoy instead of brief intense surges that blow poo poo up. It's why power blinks out during thunderstorms. grover fucked around with this message at 02:40 on Jun 12, 2011 |
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Jun 12, 2011 02:38
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grover posted:heh, like that will do jack-all if your house is hit by lightning.  Holy poo poo I never knew that. I always assumed it was from like tress loving with the lines or something.
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Jun 12, 2011 03:05
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This is a hilariously bad presentation, but describes the process pretty well: http://www.arresterworks.com/pdf_file/what_is_an_arrester.pdf One clarification, though- while low-voltage surge suppressors use MOVs and a medium-voltage MOV is described here, high-voltage lightning arrestors use spark gaps instead of MOVs; it's designed so that a lightning strike will spark to ground and conduct through. Net result is the same. Here's what they look like installed: (3 lines on the top are the 3 "hot" conductors, and the line below is the neutral/ground.) 
grover fucked around with this message at 03:31 on Jun 12, 2011 |
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Jun 12, 2011 03:25
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That was educational. Nice to brush up on that. So what are the worth of "lightning rods" and other type of systems designed to divert direct strike current around buildings and homes rather than down through them. You say a house is screwed in a direct strike (and it probably is at the very least even if it was somehow diverted thanks to lovely EMP) but would it not be a more desirable condition to have a heavily grounded cable take as much current as possible around the home instead of the lightning choosing to go down the wood and likely start fires?
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Jun 12, 2011 05:29
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grover posted:heh, like that will do jack-all if your house is hit by lightning. One of the motors at work has a lightning arrestor setup in the stator lead compartment, connects to the two lines going to each phase. I'm not sure if it's arc-gap or MOV. I believe that in the event of a lightning strike, it would take the affected phase to ground, and the Multilin would see that sudden changes in current and voltage, and trip the circuit breaker for the motor due to a ground fault/voltage imbalance/phase loss/current imbalance. Don't forget that on HV transmission lines, you also have an upper wire that's there to (hopefully) grab the lightning instead of having the lightning conduct to one of the phases. (There's a school of thought that the line protects a 90 degree area under it, and another school of thought that indicates the protection area is like the space under two touching circles.) dietcokefiend posted:
Power lines also have recloser systems. So if there's a fault, the breaker opens, but then closes after a second in case whatever caused the fault (lightning strike, fried squirrel/bird, etc) has gone away. It'll try this a set number of times, then give up and fault out. A large number of faults on lines are temporary, so that makes things easier for everyone involved. grover posted:Motor protection is a voodoo science unto itself. Breakers and fuses have different trip curves, and often must be used in conjunction to properly protect a piece of equipment. It can get rather complex and is often a specialist field. You can't just use any fuse that fits, either, as there are different types of fuses, even within the same current rating. You have to go through the documentation and see what the design engineer specified. Heh, I just use CAPTOR in PowerTools to draw and coordinate time-current curves. (We need a combination of  and .)
Three-Phase fucked around with this message at 13:41 on Jun 12, 2011 |
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Jun 12, 2011 06:32
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I'm working on a basement remodel and I want to add a few outlets on exterior walls. Currently there is paneling on 1/2" furring strips, and ideally I just want to screw 1/2" drywall on top of that. We have existing hot water baseboard heat, so adding studs to get the depth needed for outlet boxes is out. I'm ok with surface mounted outlet boxes, but if there is an appropriate way to hide the wiring behind the paneling before I install the drywall I think that would be nice. I want to run CAT6 and coax as well (which I assume is AOK to run behind the paneling since it is low voltage). So my questions are: 1) Can I run romex behind the existing paneling? Or does this need to be in conduit? 2) Can I run romex and come into a surface mounted box by code? 3) If I can't run conduit/romex behind the existing paneling, should I just look at a wiremold system and run the wire right on top of the baseboards so it's less noticable?
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Jun 20, 2011 15:55
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