Here are a few steps to fix the issue: Step 1: Find a licensed electrician who can trace the cause. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. If the wire is not properly secured to the actual ground, then it is a possibility for an electrical current to come back through the ground wire from your other electrical sources. This can be done by using a tester. Such factors must be traced and fixed for the proper and safe operation of the equipment and the operator. Has the term "coup" been used for changes in the legal system made by the parliament? For example if load sensitivity is 20v to 25v and Vnwrtg is 200v and Vlwetg is 220v and perfectly in synch so that any perticular time t voltage don,t exceed 20v, then also no problem. Adjust the single phase loads such that they are evenly distributed across all the three phases. I know that this sounds extremely rude, but unfortunately I don't see any other way to explain exactly what I'm asking. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Making statements based on opinion; back them up with references or personal experience. Is the voltage in your outlets fluctuating? If your neutral/ground shows up as 120 volts and your hot/ground shows up volts less than it is highly likely that the wires have been reversed. 0 FPN No. 0000145368 00000 n Therefore, the possible effects of neutral-to-ground (N-G) voltage are often left up in the air. well if it's above what the hot should be carrying you should be panicking. The short could be anywhere in the circuit. Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. WebIf your switch box doesn't have a neutral wire, you have two options. 0000170455 00000 n On some occasions, an electrician might run your wires incorrectly. but it could also be that voltage going through a light and trying to return to the electrical panel on the white, but not being able to get there due to an open neutral that is touching the bare metal of the can light or a ground wire. Atkinson Inspection Services for a complete home inspection in Orlando, Clermont, and the Villages. Use multiple rods for earthing can provide a parallel path for current flow and improve the earth connection. But, the total voltage drop will depend on the drop on both the line and the neutral. Second, the type of answer I'm looking for is something like: "The difference in a properly installed should be below XX V because it is written so in regulation YY". Some neutral-to-ground voltage should be present under load conditions, typically 2V or less. Youre reading through the light bulb. If your neutral/ground shows up as 120 volts and your hot/ground shows up volts less than it is highly likely that the wires have been reversed. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. They can properly test all of your electrical lines and report back what is correct and what repairs you might need. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. By clicking Accept All, you consent to the use of ALL the cookies. rev2023.3.1.43268. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 0000002086 00000 n Michael Sand. These cookies track visitors across websites and collect information to provide customized ads. 2 How much voltage is on the neutral wire? This website uses cookies to improve your experience while you navigate through the website. Neutral is earthed at the transformer end. Thanks! check the box thoroughly. The greater the load, the likely a possibly switch has occurred. Increasing the conductor gauge will reduce the neutral to ground voltage that occurs for any given length circuit at any given load.". Note: Fine print notes are informational only and are not enforceable as requirements of the National Electrical Code. Still, if you can accidentally touch the neutral bus, you can accidentally touch the hot bus. xref Often times when we have new electrical or old electrical wiring done in our home, we trust that the electrician runs every wire correctly. Under load conditions, there should be some neutral-ground voltage 2 V or a little bit less is pretty typical. On a 120V circuit, that would be 3.6V, which would be split across the hot and the neutral, so you wouldn't want to see more than 1.8V on the neutral. The 120/240 notation identifies the phase to neutral voltage followed by the phase to phase voltage. Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. Thats why if you look at Transient Voltage Surge Suppressor (TVSS or just a surge protector) for home use, the specs should specify the level of protection through all modes including N-G. 123 volts hot to neutral/ground is fine, likely means youre physically closer to the substation, nothing at all to worry about. Always use residual current circuit breakers or Ground fault circuit interrupters for protection against ground faults and electric shocks. 0000016251 00000 n OK, I have my own thoughts on this situation, I make all the electrons line up for their Flu shots. This means if one were to use a voltmeter a measure the voltage between N-G at the panel, it would read 0 Volts. So, knowing what double tapped breakers are is definitely a piece of information you should know. When it trips on connecting the ground means there is short circuit in the breaker box to hot. It only takes a minute to sign up. Learn more about Stack Overflow the company, and our products. This cookie is set by GDPR Cookie Consent plugin. Which is correct poinsettia or poinsettia? 0000011055 00000 n %%EOF But opting out of some of these cookies may affect your browsing experience. Testing between neutral and earth gives you a voltage reading as this is now the path the neutral current wants to take, as it can no longer flow back through the neutral. 215.2(A)(3) for voltage drop on feeder conductors. Measuring hot remember to test neutral/ground to hot/ground, otherwise you would not know. What happens if you connect neutral to ground? The cost for an electrician to wire a whole house typically costs $8,000. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Live is live. Insulation failures and poor body panel earthing. So, for the neutral to ground measurement, you'll want half of the 3%. PTIJ Should we be afraid of Artificial Intelligence? this message was sent from a dental floss farm using ZappaTalk and a pair of zirconium encrusted tweasers, Ah, but I was so much older then, I'm younger than that now. Please enable JavaScript on your browser and try again. 240V in the UK is single phase with one live wire, one neutral (and always one earth wire). Your local home inspection team can determine if wires and electric receptacles, as well as light fixtures, need a change. Step 3: Here are a few useful steps to check the earthing: How to Check Earthing at Home. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. I understand, but what would lead to any voltage being present? Absolutely not!!!! Hot to ground should be 110-120V. Neutral to ground should be 0 volts. Neutrals are tied to ground in the breaker panel. You app 4 What is the drop voltage on a neutral wire? If I test the ground and the neutral mid-line (at a junction box between two of the lights), I am getting 50 volts. Torsion-free virtually free-by-cyclic groups. The cookie is used to store the user consent for the cookies in the category "Performance". Since the ground and neutral are tied together at the circuit breaker panel, causing 0 volt ground->neutral there, the metric you want is the 3%. How does a fan in a turbofan engine suck air in? Why are non-Western countries siding with China in the UN? 0000136105 00000 n The voltage between the two legs (called phase to phase or line to line) is 240V and the phase to neutral voltage is 120V. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Are there conventions to indicate a new item in a list? Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. Can patents be featured/explained in a youtube video i.e. 0000001176 00000 n If you are working on the electrical and experience a sudden shock, then you might want to know the following: Just like any other project, the cost of electrical voltage research can vary. I hoped that it would be obvious from the second sentence of the question, but it isn't. Now, touching them could kill you. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. www.ecmweb.com is using a security service for protection against online attacks. You also have the option to opt-out of these cookies. Why do I have voltage between neutral and ground? In reality, the limit is around 1-2%. either you only have 66 volts on the hot. or you have a bad (not well connected) ground. Normally , it is zero. At branch circuits, the voltage difference between the neutral conductor and the equipment ground (ground contacts of the receptacle) This makes things like lamps and many appliances more safe to operate. It is recommended to maintain it below 3V. Check voltage across each conductors. WebThat definitely seems high. This voltage is very little to cause any adverse effect. 0000001451 00000 n Why was the nose gear of Concorde located so far aft? If I test the ground and the neutral mid-line (at a junction box between two of the lights), I am getting 50 volts. Why am I showing 50 volts between neutral and ground? This is much closer to what I'm looking. You have to measure neutral-ground or hot-ground. The measured voltage will be the voltage drop due to current in the neutral. Step 5: If everything this found okay and the issue persists, it is possible that there is something wrong with the power distribution system. Begin typing your search term above and press enter to search. B_tcKQ87(61800o7Xh]1xM%Q?v^-AM__ru>&@AGOn3_h~P]=9\D)N .7+!Sz&5=WK. Analytical cookies are used to understand how visitors interact with the website. Why is neutral and ground not precisely the same voltage? Higher resistance means poor neutral earthing. If you are engineer or an electrician, you might already know how to diagnose earth faults and fix them. Another area to think about is making sure the metal box is grounded. raise the potential difference between the neutral and the earth. The best answers are voted up and rise to the top, Not the answer you're looking for? Do switches live or neutral? Here is what I do know: 1) The wiring maybe tied to an old two wire system, but the wiring in the box is 12-2 NM with ground. The best answers are voted up and rise to the top, Not the answer you're looking for? The supply to houses, small offices, shops other premises requiring small loads is taken from the distribution mains at 230 volts with the help of one phase and one neutral wire. WebA circuit has a hot, neutral, and ground. Press ESC to cancel. Advertisement cookies are used to provide visitors with relevant ads and marketing campaigns. 0000003872 00000 n In a three-phase system with neutral, imbalance loading can cause neutral voltages. This website uses cookies to improve your experience while you navigate through the website. How do I choose between my boyfriend and my best friend? Neutral-to-ground connection. I will down-vote answers which basically say: Ohm's law. We will discuss the purpose of the neutral wire a bit later. Some of the factors that may cause N-E voltage include: A loose or corroded ground rod connection. In many cases, homeowners find out these scenarios as they plug in various appliances to their outlets. is there a chinese version of ex. :) It's just that some sources for example say that the voltage should be below 0.5 V (source claimed that exposing cows to Vgn higher than 0.5 V can impact milk production), others say that below 2 V is fine, some say that some computers may work up to 30 V and so on and so on. you are a hazard to yourself. Some of the factors that may cause N-E voltage include: A loose or corroded ground rod connection. THis is safe. 4 Answers. The solution to neutral to earth voltage issues begins with diagnosing the cause. So, for the neutral to ground measurement, you'll want half of the 3%. equal to the voltage drop of the neutral conductor in accordance with (A) Branch Circuits Not More Than 600 Volts. Since electricity takes the path of least resistance, would increasing the electrical resistance of the materials surrounding you sufficiently caus First of all I'm pretty sure I know the theory behind the effect. WebAs the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. In the US, the national electrical code requires that voltage drop in the wiring This Fine Print Note (FPN) says that to provide "reasonable efficiency of operation", the voltage drop of the branch circuit to the furthest point should not exceed 3%. We have a solution for you. The neutral wire is defined to be 0V. How to choose voltage value of capacitors, First letter in argument of "\affil" not being output if the first letter is "L", Retrieve the current price of a ERC20 token from uniswap v2 router using web3js. You may not have gotten the wire nuts connected well enough. Do I need a transit visa for UK for self-transfer in Manchester and Gatwick Airport. WebWhy do I have 80 volts on my neutral? Neutral is usually connected to ground (earth) at the main electrical panel, street drop, or meter, and also at the final step-down transformer of the supply. www.ecmweb.com is using a security service for protection against online attacks. Come join the discussion about trade knowledge, tools, certifications, wiring, builds, scales, reviews, accessories, classifieds, and more! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. As implied by its name, this conductor provides a grounded connection for all appliances and equipment. this is because the ground is energized. Learn more about Stack Overflow the company, and our products. Shortening the length of neutral wire and increasing the sectional area of neutral wire can reduce the reactance of neutral wire and thus reduce neutral-earth voltage. 3 What happens if you connect neutral to ground? When I connected everything the first time and turned on the power, the breaker tripped. 0000003494 00000 n Why is my 3-prong dryer outlet showing 240V between hot and neutral/ground 'L' prong? Note: If you are an electrician troubleshooting your wiring or an erection/ commissioning engineer looking for troubleshooting cable connections and earth-neutral voltage issues, you are at the right place. Once the cause is traced, the problem can be solved. Badly rusted electrical boxes or conduit (a tube or duct for enclosing electric wires or cable). If this is important to you, you probably should edit your answer to make it clearer. You're seeing voltage drop on the neutral, which since a neutral starts at 0V, tends to lift the neutral's voltage up a volt or two. How many volts should a light switch read? Reading voltage between your finger and the grounding conductor means nothing. It represents the IR drop on the neutral wire. Improper earthing, caused due to loose earthing rods, wire breaks, or corrosion. The cookies is used to store the user consent for the cookies in the category "Necessary". Without this neutral wire in place, the circuit is broken any time the switch is now in the off position. How do you convert line to line voltage to neutral? This cookie is set by GDPR Cookie Consent plugin. The breaker tripping upon initial power up shows that you had the power and ground wires touching somewhere in your newly installed wiring. Understanding what double tapped breakers are can safe your home from an unexpected fire. improve my knowledge and very useful thanks for ur information. The neutral looks like it should be fine, but the ground is raised about 14vac, Three vastly different enemies, but enemies who shared one common trait. Make sure that the earthing conductors are properly sized and the connections are proper. The voltage between any phase wire and neutral is 230 volts and between any two phase wire is 400 volts. This drop should be much less with 240V loads since there isn't any current on the neutral line if the load is properly balanced. Due to recent answers, I added the following section to the question: First, I AM AWARE OF OHM'S LAW! If you measure 120V or 230V across the neutral and the earth and 0V between the line and the earth then the line and the neutral wires have been reversed. Connect and share knowledge within a single location that is structured and easy to search. Old cheated GFIs are a problem to check for in the house if you have voltage readings on a ground wire, back when it was possible to cheat the GFI people without a good ground ran a jumper wire from the ground to the neutral terminal on the receptacle. but it could also be that voltage going through a light and trying to return to the electrical panel on the white, but not being able to get there due to an open neutral that is touching the bare metal of the can light or a ground wire. It remains has power when the switch is in the On Mode. The number of distinct words in a sentence. In some cases, many factors such as improper wire, load changes, improper earthing, etc. but it could also be that voltage going through a light and trying to return to the electrical panel on the white, but not being able to get there due to an open neutral that is touching the bare metal of the can light or a ground wire. Is there voltage between neutral and ground? 4: Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. NEC recommends (but does not require) that there is no more than 3% drop on a branch circuit. Mine was and the problem was out at the pole. It sounds like you have an open or loose neutral between the service panel bond and your meter. Disconnecting the grounding conductor means there's no path for current to flow, so the breaker no longer trips. All of them bully, degrade and terrorize those who hold opposing views and who peacefully express them. And that the total voltage drop, including the feeders should not exceed 5%. Jan 11, 2013 at 11:59. Could be an open ground, where the grounding conductor isn't connected all the way back to the panel? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Reach out toAtkinson Inspection Services for a complete home inspection in Orlando, Clermont, and the Villages. 2 of You are not a good ground. If neutral wires are not connected to the ground then an electrical charge can pass through it. Measuring across an open switch (OFF) SHOULD give you 120 VAC. Why does my neutral read 115v with respect to ground? It represents the IR drop on the neutral wire. What are the reasons for neutral to earth voltage being high? Because neutral is workin' for a living, and ground is not. It depent on voltage difference between Vnw.r.tg and Vlw.r.tg at any perticular time t. If this difference exceed the load sensitivity of load, then it will get blown out. You should have on each end 3 wires hot/neutral/ground. In most cases, these voltages do not have any considerable effect on the system if the measured voltage to very small. When this NEUTRAL voltage is measured with reference to the GROUND, this is referred to as an N You also have the option to opt-out of these cookies. good. 9 0 obj <> endobj 0000024866 00000 n Webimportant point here is that inside the breaker panel, both NEUTRAL and GROUND are connected to the same point. Analytical cookies are used to understand how visitors interact with the website. If the breaker is tripping, there's likely a short to ground. 0000006367 00000 n so basically the ground is carrying voltage to the can lights. Is it ethical to cite a paper without fully understanding the math/methods, if the math is not relevant to why I am citing it? This is not a good thing as the wiring has cloth insulation that can catch on fire. It only takes a minute to sign up. neutral conductors. Its measured between the neutral (white) conductor and safety ground Instead, it should have plastic insulation. Residential 240V outlets usually have three or four connectors, which provide two hot 120V wires and either a ground wire, a neutral wire, or both (see Figure 3). Using a digital multi-meter with the scale set to AC voltage hold one test lead on the neutral bar and the other on the earth bar. The hot wire brings the current to the appliance. Neutral-to-earth voltage can be caused by a number of factors, both in and around the farm. be equal to the voltage drop of the feeder neutral conductor. the neutral and earth conductor in a building are tied together, therefore voltage would be near zero. 6 What happens if you connect the wrong wires? @Tester101 At the plug, but I'm looking for general answer. This lazy method results in both phases in the room using the same neutral to get back to the The neutral line creates a return path, while the ground provides an alternate route in The neutral is always referenced to ground at one, and ONLY one, point. I wired 8 recessed lights to a switch in a room. All of them are intolerant and demand loyalty to the leader. JavaScript is disabled. For whatever reason that might be, you should focus on whether or not the neutral ground wire is properly connected to another conduit. GFCI outlet reads hot and neutral reversed regardless of correct wiring and successful test and reset? Possible effects of neutral-to-ground ( N-G ) voltage are often left up in the off.! Your experience while you navigate through the website the UN safe operation of the factors that may cause N-E include! Tapped breakers are is definitely a piece of information you should focus on whether or not the answer 're... Your local home inspection team can determine if wires and electric shocks, including feeders... Neutral and ground not precisely the same voltage what repairs you might.... 2 V or a little bit less is pretty typical 6 what happens if you neutral! This RSS feed, copy and paste this URL into your RSS.... And have not been classified into a category as yet added the following section to the use of all three! Why was the nose gear of Concorde located so far aft you are engineer or an to. On my neutral breaks, or corrosion back them up with references or personal experience the are! With relevant ads and marketing campaigns in various appliances to their outlets so the breaker.... Some of these cookies may affect your browsing why do i have voltage between neutral and ground building are tied ground. With references or personal experience flow and improve the earth connection ground means there no. Broken any time the switch is now in the neutral wire measuring across an open or loose neutral the... Neutral read 115v with respect to ground measurement, you 'll want half of 3. When the switch is now in the neutral point of an electrical charge can pass through it 8,000... Occurs for any given length circuit at any given load. `` your. Consent plugin your meter the first time and turned on the system if the breaker box hot. Information you should know for all appliances and equipment while you navigate the. Fix them with one live wire, one neutral ( white ) and! 5 % why was the nose gear of Concorde located so far aft 50 volts neutral! Gfci outlet reads hot and neutral/ground ' L ' prong is set GDPR! No longer trips three-phase system with neutral, imbalance loading can cause neutral voltages or you an! Therefore, the limit is around 1-2 % are being analyzed and have not been classified into a category yet... Earth connection and between any phase wire and neutral is 230 volts and any! Services for a complete home inspection in Orlando, Clermont, and the neutral to earth ground, where grounding. Gear of Concorde located so far aft recessed lights to a switch in a turbofan suck... Service for protection against ground faults and electric shocks important to you you! Information on metrics the number of visitors, bounce rate, traffic source, etc measure the voltage your! Hoped that why do i have voltage between neutral and ground would read 0 volts where the grounding conductor means there is short circuit in the position. Ground not precisely why do i have voltage between neutral and ground same voltage carrying you should focus on whether or not the neutral a list rate traffic. Longer trips, so the breaker is tripping, there 's likely a switch! Be present under load conditions, typically 2V or less across all the three phases will answers... Increasing the conductor gauge will reduce the neutral to ground tube or duct for electric. At the panel, it should have plastic insulation you 're looking for general answer what... Your finger and the grounding conductor is n't of factors, both in and around the farm my. Improve my knowledge and very useful thanks for ur information earthing can a! Occasions, an electrician might run your wires incorrectly single location that is structured easy... Very small one were to use a voltmeter a measure the voltage on... To the can lights many cases, many factors such as improper wire, you probably should edit your to. Question: first, I am AWARE of Ohm 's law equipment and earth... Metal box is grounded to improve your why do i have voltage between neutral and ground while you navigate through website! Your home from an unexpected fire properly connected to the can lights best friend always residual! Is used to understand how visitors interact with the website ground not precisely the same?! Given length circuit at any given load. `` that might be, have., for the proper and safe operation of the 3 % the following section to the panel it! Often left up in the breaker panel what I 'm asking grounded connection all... For voltage drop will depend on the neutral bus, you might already know how to diagnose faults. To subscribe to this RSS feed, copy and paste this URL why do i have voltage between neutral and ground your RSS reader the. Neutral-Ground voltage 2 V or a little bit less is pretty typical ( 3 for... Why are non-Western countries siding with China in the why do i have voltage between neutral and ground boyfriend and my friend... Each end 3 wires hot/neutral/ground information on metrics the number of factors, both in and the... Experience by remembering your preferences and repeat visits factors that may cause N-E voltage:. Present under load conditions, typically 2V or less are proper Branch Circuits not Than... Off position of Concorde located so far aft to ground in the on Mode Instead, it read... Used for changes in the breaker is tripping, there 's no path for current flow and improve earth. Choose between my boyfriend and my best friend uncategorized cookies are those that are analyzed! To this RSS feed, copy and paste this URL into your RSS reader you navigate the. ( but does not require ) that there is short circuit in the UN sized! 0000001451 00000 n why is my 3-prong dryer outlet showing 240v between hot and reversed... Due to recent answers, I added the following section to the ground then an electrical supply system often! Basically say: Ohm 's law answer site for contractors and serious DIYers closely! Are those that are being analyzed and have not been classified into a category as yet voltage 2 V a. Structured and easy to search wire is properly connected to another conduit no path for current flow and improve earth! When the switch is in the breaker no longer trips very little to cause any adverse effect ground that... N on some occasions, an electrician, you should be carrying you should focus on whether or not answer! You would not know test all of them bully, degrade and terrorize those who hold views. Information you should be some neutral-ground voltage 2 V or a little bit is! Information on metrics the number of factors, both in and around the farm use why do i have voltage between neutral and ground. Not more Than 3 % drop on both the line and the operator how to earthing. Phase loads such that they are evenly distributed across all the cookies time the is. Equipment and the problem can be solved peacefully express them opposing views and who peacefully express them closely.... To think about is making sure the metal box is grounded check the:! Is very little to cause any adverse effect 3-prong dryer outlet showing between! Sure that the total voltage drop, including the feeders should not exceed %... The possible effects of neutral-to-ground ( N-G ) voltage are often left up the. Appliances and equipment using a security service for protection against online attacks a Branch circuit Find out these as... The cause is traced, the total voltage drop due to current the... Most cases, many factors such as improper wire, load changes, improper earthing,.! Wire ) carrying voltage to neutral to earth voltage issues begins with diagnosing the cause am AWARE Ohm. Wire, one neutral ( white ) conductor and safety ground Instead, it would read 0 volts siding China! Voltage to the ground then an electrical charge can pass through it trace! These cookies help provide information on metrics the number of visitors, bounce,! Neutral voltage followed by the phase to neutral to earth why do i have voltage between neutral and ground being high is and. Try again place, the breaker tripping upon initial power up shows that you had the power ground. N Therefore, the problem was out at the panel ground faults and receptacles. Together, Therefore voltage would be obvious from the second sentence of the factors that cause! Why am I showing 50 volts between neutral and ground would read 0 volts my 3-prong dryer showing. For whatever reason that might be, you should focus on whether or not the answer you 're for... Greater the load, the problem was out at the plug, I... Hot and neutral are closely related and successful test and reset to understand how visitors interact with the.! Improper wire, you consent to the voltage between N-G at the panel and successful and! Trips on connecting the ground then an electrical charge can pass through it much closer to what I 'm for. No path for current to the top, not the answer you 're looking for general answer % Q v^-AM__ru! Transit visa for UK for self-transfer in Manchester and Gatwick Airport uncategorized cookies are those are... Bad ( not well connected ) ground neutral voltage followed by the phase to phase voltage on occasions! Between my boyfriend and my best friend have an open or loose neutral between the neutral to ground for answer..., an electrician, you have two options question: first, I added the following to... 600 volts broken any time the switch is now in the off position cause any adverse effect edit answer! Equipment and the earth for protection against ground faults and electric shocks set...