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Post by tom738 on Oct 17, 2016 2:54:15 GMT -6
I own a home in the Orlando, FL area built in early 2012 by a large national builder in one of their developed neighborhoods. Recently some people have claimed their homes are NOT grounded per code. I find this hard to believe as the electrical contractor and city inspectors would be grossly negligent. My home is called "patio home" another term for a duplex with a shared wall. I think my part of the duplex would have a separate and distinct electrical system including grounding. I'm not referring to grounded outlets....instead referring to whole house / system ground with rod or other device. What is the easiest way I can determine if the grounding exists? Where exactly should I look? The utility company (OUC) recently installed a whole house surge protector at the meter. Would that block any buildup of electricity caused by lightning strike nearby or other loads that would be dissipated via a grounding rod? I feel if code calls for a grounding rod then that's what I should have. Maybe it's grounded to other metal line coming in to home from street. Is there a new way to achieve grounding other than use of rod in ground? Really appreciate your help on this. Thanks!
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Post by westom on Oct 18, 2016 7:15:43 GMT -6
Find the bare copper, quarter inch wire or wires that leave the main breaker box. Those would be your grounds. Ground can only be determined by inspection.
Earth ground that makes that protector effective is a low impedance connection to earth. That means as short as possible (ie less than 10 feet), wire has no sharp bends (Ie does not go over foundation), is separated from other non-grounding wires, no splices, and is not inside metallic conduit.
An earthing electrode can be a single (more than 8 foot) copper clad steel rod. Better earthing electrode is multiple ground rods separated by at least five feet. Or Ufer grounds. That protector is only as effective as its earth ground. Defined are requirements necessary to exceed code requirements. So that the protector is not compromised.
No effective protector 'blocks'. That is what ineffective (ie plug-in) protectors must do.
Best protection on your TV cable is a hardwire from the cable's ground block and low impedance (see above examples) to single point earth ground. That hardwire is best protection. A protector is only doing what that hardwire does better. Connect a surge current harmlessly into earth. Because a protector is only as effective as its earth ground.
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Post by Electrical Code Academy Staff on Oct 18, 2016 11:14:35 GMT -6
Greetings Tom738 and westom, All electrical systems that you describe require a grounding electrode system. The installation of a whole house surge protector is irrelevant to the requirements of a GES (Grounding Electrode System). You should (in your panel) have at the least a 6 AWG CU to a ground rod(s) or 4 AWG to a concrete encased electrode depending on which may be installed. In fact, you could have a number of possible electrodes installed in accordance with NEC Section 250.52(A). Being very careful of course, looking inside your electrical panel cans how you how to identify if their is a GEC (Grounding Electrode Conductor) and that would be the first start. As for the local AHJ and builder, it is hardly possible that a home built in 2012 would not have a grounding electrode system. It sounds like you are in a duplex which is still considered a single building (unless there is a firewall that separates your dwellings and it actually qualifies as a firewall) with a fire rated assembly separation. My suggestion is to inspect the panel first and if you are not familiar with that we do have a video on that at www.electricalcodeacademy.com but it is not free (Sorry) Now Westom - thank you for the info and I do not edit posts so I will correct your statement here. The multiple ground rods would have to be no less than 6' apart to be code compliant with section 250.53(B). It also can't be a single ground rod unless it can comply with the requirements of section 250.53(A)(2) and the exception that follows. So back to Tom.....You need to look in your panel (Carefully) and see if you can find that GEC as stated earlier. Again there are many possible electrodes that can be used. Also if your electrical panel is inside the dwelling, away from an exterior wall then you may have a disconnect outside as well and that may be the location of your grounding electrode system. The quick way to determine that would to notice the number of conductors supplying your inside panel...if it has 4 conductors (2 hots, 1 neutral and 1 equipment grounding conductor) then you have an additional service disconnect somewhere else on the premise to look for and at. Hope this helps....and if you want to take a picture of your panel and post it....I most certainly will comment on what I see if that helps also....kinda like a Virtual Inspection.
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Post by westom on Oct 18, 2016 14:22:08 GMT -6
The multiple ground rods would have to be no less than 6' apart to be code compliant with section 250.53(B). It also can't be a single ground rod unless it can comply with the requirements of section 250.53(A)(2) and the exception that follows. Correctly noted is an exact number - 6 foot separation. A single ground rod is acceptable - for human safety - when it means an exception that only defines human safety. We are discussing something that must both meet and exceed code requirements. Appliance safety. Single point earth ground is not a single ground rod. Single point earth ground is a single rod or a massive earthing system (ie Ufer ground) that every wire in every incoming cable must connect to. That includes TV cable, phone, invisible dog fence, lawn sprinkler system, satellite dish, AC electric, and any wires to other detached buildings (ie garage). TV cable, phone, and satellite dish should already have effective protection as required by human safety codes. And installed for free. Earth ground can meet code and be all but non-existent to protectors. No earth ground means even a world's best protector is compromised - ineffective. Code defines many electrodes that can create this single point earth ground. But an earth ground that meets requirements for human safety (ie low resistance) can also provide insufficient grounding for a protector - due to high impedance. As described in a second paragraph of that previous post. Code (and electricians) discuss earth concepts based in resistance - for human safety. Protectors required earth concepts based in impedance - for appliance safety. This solution is especially necessary in Orlando where the frequency of surges is significantly higher than what most in the world sees: one potentially destructive surge every seven years. No protector does protection. Not one. Protectors are only connecting devices to what must harmlessly absorb hundreds of thousands of joules. That same earth ground that meets code requirements must also exceed code requirements to provide effective appliance protection. A 'behind the meter' protector should meet requirements for protector life expectancy over 'many' direct lightning strikes and many decades. But to be effective for 'each' transient, that protector must also make a low impedance connection to single point earth ground. Nobody suggested removing a main breaker panel cover. Single point earth ground must be located at the other end of a bare copper, quarter inch wire. It must connect that main panel low impedance (ie less than 10 feet) to earth ground. That connection and electrode defines a building's 'secondary' protection layer. A utility installed earth ground is a 'primary' protection layer. Each layer of protection is only defined by its earth ground - not by any protector. Again, that utility installed protector will only be as effective as the earth ground that a homeowner has provided and maintained.
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Post by Electrical Code Academy Staff on Oct 18, 2016 15:17:26 GMT -6
It was stated to look inside the panel.
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Post by westom on Oct 19, 2016 6:33:40 GMT -6
It was stated to look inside the panel. "Find the bare copper, quarter inch wire or wires that leave the main breaker box." Opening or looking inside a panel is neither required nor stated. That utility installed protector, like all protectors, will only be as effective as its earth ground.
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Post by Electrical Code Academy Staff on Oct 19, 2016 6:41:44 GMT -6
The fact the NEC requires no less than (2) ground rods is a fact. The NEC is a minimal safety standard and it demands, where ground rods are used, that their be two of them unless the exception applies. If the installer can show 25 ohms or less from a single ground rod then it would acceptable. However, in the 2014 NEC (and 2017) the requirement is no less than 2 unless you show the exception is applied and compliant.
The reference to earth ground for electronics and so on is not really within the original posters request. The surge protective device installed by the utility is not relevant to the lack of a grounding electrode system. The message provided in my response will assist him/her in locating that system or the lack of.
FYI - I stated "Being very careful of course, looking inside your electrical panel cans how you how to identify if their is a GEC (Grounding Electrode Conductor) and that would be the first start."
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Post by westom on Oct 19, 2016 17:32:06 GMT -6
The surge protective device installed by the utility is not relevant to the lack of a grounding electrode system. Then we electrical engineers must teach electricians. A protector without a low impedance connection to earth does not do and does not claim to do effective protection. Any claim without numbers is best ignored. This will include plenty of numbers that separate hearsay and wild speculation from what well proven science says. And even professional case studies. One earth ground rod is more than sufficient if earthing is less than 25 ohms - resistance. In appliance protection, impedance, equipotential, and other engineering concepts apply. None are defined or discussed by safety codes. All say why that utility provided protector must connect low impedance to earth. Second, one earth ground rod or 100 is completely irrelevant to what was posted: single point earth ground. Somehow two earth ground electrodes are confused with a completely different concept - single point earth ground. One electrode or 100 can be a single point earth ground. Third, receptacle safety ground clearly does not provide earth ground for a long list of technical reasons. Wire too long. Many sharp bends. Splices. Not separated from other non-grounding wires. All seriously increase impedance. More numbers. a 50 foot Romex wire is maybe less than 0.2 ohms resistance. Electricians would know that. That same wire can be 120 ohms impedance. Electricians are not taught that. What happens if a safety ground wire tries to earth a tiny (100 amp) surge? 120 ohms times 100 amps = 12,000 volts. Please learn why low impedance (not discussed in safety codes) is essential for a protector to be effective. And why a utility installed protector must somehow make a low impedance (ie less than 10 foot) connection to single point earth ground. Fourth, if a protector is not connected low impedance to earth, then it must either 'block' or 'absorb' that surge. How do 2 cm protector parts 'block' what 3 kilometers of sky cannot? It doesn't. How does its hundreds or thousand joules 'absorb' a surge that is hundreds of thousands of joules. It doesn't. It does not even claim to. What makes that utility installed (or any other) 'whole house' protector so effective? Same thing that makes lightning rods effective. Earth ground. World's best lightning rod does no effective protection without the most critical component of any protection 'system'. Earth ground. Then a structure is protected. World's best surge protector does no effective protection without the most critical component of that protection 'system'. Earth ground. Then appliances are protected. Above was well understood well over 100 years ago. Protection is always defined by an answer to this question: Where do hundreds of thousands of joules harmlessly dissipate? Those numbers define an informed recommendation. A protector (including that utility installed protector) is only as effective as its earth ground. Only then is a question, with numbers, answered. We engineers have made surges (including direct lightning strikes) irrelevant for decades. And yes, I also learned from my human mistakes. In every case, when damage occurred, then a resolution began with the most common reason for damage - a defective, not maintained, or compromised earth ground. Ufer grounds were pioneered in munitions dumps so that surges did not cause explosions. Because surge protection is always about how a surge harmlessly connects to and dissipates in earth. A Nebraska radio station learned this the hard way. Only solution to stop all future damage was to upgrade or restore earth grounds. The case study: www.copper.org/applications/electrical/pq/casestudy/nebraska.htmlBTW, they even upgraded a 'primary' surge protection layer by upgrading what defines protection - a telephone pole earthing electrode. What makes that utility installed protector so effective? A protector is only as effective as its earth ground - where hundreds of thousands of joules harmlessly dissipated even over 100 years ago.
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Post by westom on Oct 20, 2016 6:17:10 GMT -6
I think you are elaborating in something that is not representative of the original posters intent. However, thank you for the additional content. The original poster asked Posted is what makes that utility installed 'whole house' protector effective so that a surge dissipates via a grounding rod. And why the NEC (safety code) does not provide or define a sufficient or effective installation. That 'whole house' protector and earth ground must both meet and exceed NEC. And all other incoming utility wires (ie TV cable, phone, OTA antenna, and satellite dish) must also both meet and exceed safety codes. Otherwise protection by that utility installed protector is compromised. For example, best protection for TV cable is a hardwire from cable to single point earth ground. That wire is required by code. But to provide effective protection, it also must be low impedance (ie less than 10 feet, no sharp wire bends, not inside metallic conduit, etc) to that earth ground. An AC electric utility also defines a good, bad, and ugly (preferred, wrong, and right) construction and connections to single point earth ground: www.duke-energy.com/indiana-business/products/power-quality/tech-tip-08.asp"Right" meets code. "Preferred" is necessary to make a protector effective. Another example of how effective protection exceeds what safety code (NEC) requires. So that the Original Poster's utility installed protector works properly - as he requested.
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Post by Electrical Code Academy Staff on Oct 20, 2016 7:10:01 GMT -6
He is concerned about the lack of a grounding electrode system and how to locate it and less about the effects of the DVD.
But I can't speak for the original poster.
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Post by Electrical Code Academy Staff on Oct 20, 2016 8:00:48 GMT -6
I will stick with the NEC and leave the utility supplied SPD to them. Having taught 1000's of engineers and electricians in my time, it is the NEC that is my specialty and I will leave the dynamics of of the SPD to you my friend.
The lack of a grounding electrode system is the key for me and if the utility is placing such a device that will utilize the GES then it appears that they assume one exists.
Knowing that the explanation of an SPD is more than likely above the knowledge of the poster they key thing they should focus on is the GES and lack thereof in my opinion.
All great info but again this is an NEC forum so it kinda focuses on the aspects of the NEC. However, I love the additional information as its awesome and thank you for contributing to the forum.
Also just an FYI, nothing within the NEC prohibits installing the GEC in a metal raceway as long as the bonding aspects of 250.64 (E) with regards to ferrous raceways and enclosures.
Coincidentally enough I happen to sit on Code Making Panel 5 so love the discussions.
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Post by westom on Oct 20, 2016 19:45:03 GMT -6
Also just an FYI, nothing within the NEC prohibits installing the GEC in a metal raceway as long as the bonding aspects of 250.64 (E) with regards to ferrous raceways and enclosures. Correct. Because NEC only addresses human protection issues. Appliance protection means both meeting and exceeding code requirements. NEC grounds are about resistance. Same ground for appliance protection is about impedance. If a wire is inside metallic (ferrous) raceways, enclosures, or conduit, then impedance increases significantly. Routing wires through a ferrous bulkheads was a technique to increase impedance - encourage a surge to find earth ground by some other path. But a path to each ground must have low impedance (ie less than ten feet, no splices, no sharp bends, etc). Nothing in code addresses appliance protection. Dr Standler complains about this situation in his book "Protection of Electronic Circuits from Overvoltage":
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Post by westom on Oct 24, 2016 12:17:46 GMT -6
While the subject of the forum states that the grounding and bonding applications are as referenced in the National Electrical Code I have also added the notation that it is for NEC aspects only. OP asked What the OP asked is irrelevant to what the National Electrical Code defines. So his original question does not belong in this forum. Again, the point. A protector (every protector) is only as effective as its earth ground. NEC does not define what is required. Whereas a protector is installed to meet human safety requirements in the NEC, it must also exceed those requirement to do anything effective (ie protect appliances). Discussion of grounding and bonding per NEC is only for human safety. Protection of appliances involves concepts (well proven science) not discussed by and is not the purpose of the NEC. Therefore the OP's original post does not belong in this forum. A fundamental difference exists between what the NEC discusses and what is necessary to protect appliances.
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Post by Electrical Code Academy Staff on Oct 24, 2016 12:48:01 GMT -6
I have moved the thread into the General Electrical Discussions Forum. Now have at it....
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