Talk:Earthing system

Grounding current equation

Should this: "the equation IL1+IL3+IL3+IN = 0 holds" be L1 L2 L3? --Jmeden2000 23:00, 29 November 2005 (UTC)

Yes. Now fixed. Markus Kuhn 23:14, 29 November 2005 (UTC)

Terre

French : terre, earth (is originally from from the Latin terra)194.83.51.64 11:09, 16 May 2006 (UTC) John

Region?

There should be more info. about which regions prefer "earthing", "earthing system", as compared to "ground", "grounding", "grounded", "grounding system"?

This does seem extremely dependent on dialect, region, neighborhood.

earth_ground;

ground_(electricity);

ground_(electrical);

ground_(power);

ground_and_neutral.

Then there is "earthling".

hopiakuta ; [[ <nowiki> </nowiki> { [[%c2%a1]] [[%c2%bf]] [[ %7e%7e%7e%7e ]] } ;]] 22:25, 24 October 2006 (UTC)

As the article says, it follows IEC 60364 terminology, on which the wiring regulations of many countries are based, but which differs from the terminology most commonly used in North America. You are welcome to append a section on U.S. terminology. Markus Kuhn 14:00, 16 September 2007 (UTC)

I also think that the IEC 60364 terminology used in the article is used at least in the whole EU (for example terms like TN-S, TNC-S are used in harmonised EU terminology in most european languages). I am afraid that the "extreme dependence on region" is just in Your head, mixing earthing system and earthling is demagogical. --85.207.59.18 (talk) 15:06, 23 August 2010 (UTC)

Why doesn't someone merge the two articles earthing system and ground_(electricity) then, and put all variants and redirects in the same article? Doseiai2 (talk) 09:28, 5 December 2007 (UTC)

Because these are two different things. The earthing system is about how the electrical network is realized having in mind the protection against electrical shock. The electrical ground is present even if there is no network and even if we know nothing about electricity at all, it is reality, part of environment here on Earth. We had lightning rods before electrical networks. By the way, there is some chaos around "earth" and "ground" even in languages that use the same word for both (like Czech). For example, you should make sure whether you mean "common" or "ground". There is a nice article about it ... [1]; in case the link is invalid try to search for Can we find common ground about "common" and "ground"?. --85.207.59.18 (talk) 15:06, 23 August 2010 (UTC)

IT diagram missing neutral

IT-network diagram

The IT Network diagram is missing the neutral conductor. 142.59.176.154 19:56, 13 September 2007 (UTC)

As I understand it, there is no distinction between "live" and "neutral" conductors possible in IT networks, because none of the conductors has a connection to earth. Whether 3-phase IT networks are commonly used, and whether these do include a fourth neutral-like conductor connected to the center-point of the generator-star, I don't know. (I would appreciate references on this; the few IT networks that I have encountered personally were all single-phase.) The figure that I uploaded was inspired by one shown in DIN VDE 0100-300, the German version of IEC 60364-3:1993, which does not show any N connection between generator and consumer. Markus Kuhn 13:53, 16 September 2007 (UTC)

The NEC clearly defines the neutral wire even if it is not grounded. First, it defines the “neutral point”, as the common point of a split-phase (single-phase three-wire) connection or a polyphase wye/star connection. Then, it defines the “neutral conductor” as the wire connected to the neutral point and that is intended to carry current under normal load conditions. So, there is a distinction between a live/hot/active/phase wire and a neutral wire even in ungrounded systems. Also, in perfectly balanced conditions, the current through the main neutral wire in single-phase three-wire and three-phase four-wire connections is zero; this is another way to distinguish the neutral wire from the live wire. Alej27 (talk) 13:52, 13 December 2023 (UTC)

Questions

"A protective earth (PE) connection ensures that all exposed conductive surfaces are at the same electrical potential as the surface of the Earth,"

The UK uses a PE connection yet lots of exposed conductive surfaces are not connected to it.

"TN networks save the cost of a low-impedance earth connection at the site of each consumer. Such a connection (a buried metal structure) is required to provide protective earth in IT and TT systems."

Portable generator IT systems routinely have no earth and no RCD. Tabby (talk) 00:55, 8 December 2007 (UTC)

Can any one tell why a capacitor is used in earthing circuit?

 —Preceding unsigned comment added by 203.115.103.71 (talk) 13:54, 26 December 2008 (UTC) 

In the phrase "hazardous IR voltage drops" what does "IR" mean? It does not seem to occur anywhere else in this article. 138.251.194.28 (talk) 11:41, 26 July 2011 (UTC)

It probably could be worded better. Almost all conductors have resistance, when current flows through them, the voltage at one end will be different from the voltage at the other end due to the resistance. If the resistance is the only concern, and inductance can be neglected, the difference can be found by multiplying the current through the conductor, I, with the resistance of the conductor, R, or stated algebraically, IR. Jc3s5h (talk) 12:07, 26 July 2011 (UTC)

What about corner grounded delta?

Is this system still relevant? It is a variation of TN system, having kind of LPEN conductor. --87.100.136.59 (talk) 22:04, 25 February 2013 (UTC)

Change in reference

There was a change in a reference. The reference should not be changed for two reasons. First, the reference list should show the works that were actually used to write the article. Unless the article is changed, there is no reason to change the reference list. Other interesting works that were not used to write the work could be put under an External links or Further reading heading.

Second, the first work was under the control of an author and publisher, and was probably a reliable source. The replacement work is a wiki, and should not be cited, just as Wikipedia should not be cited. (See WP:IRS.) Jc3s5h (talk) 14:44, 13 August 2010 (UTC)

Dawnseeker, your plagiarism will not be tolerated. Jc3s5h (talk) 03:10, 3 April 2011 (UTC)

Whoa. Slow down... Plagiarism is defined as "the unauthorized use or close imitation of the language and thoughts of another author and the representation of them as one's own original work". My edit does not match that definition.

My decision to remove the link and replace it with another was because of the commercial nature of the www.tlc-direct.co.uk website. The book that I replaced it with seems like a more neutral reference. It is not a wiki as you claimed and is a decent source for the article. Most of that book is available on google and meets the requirements of WP:RS. Dawnseeker2000 03:25, 3 April 2011 (UTC)

The references section of Wikipedia articles, per Wikipedia:Manual of Style (layout), is used to cite works that were used in writing the article. Unfortunately earlier editors did not use footnotes, but we must presume that some part of the article is based upon the reference you used removed, unless you can prove otherwise. There was no plagiarism while the source was acknowledged, but when you removed the source, you created plagiarism. The only proper way to remove the source, whether it is a good, bad, or indifferent source, is to find what part of the article is based on it and rewrite that part, based on some other source(s).

Bear in mind that when an article is written by a group, it is the collective actions of the group that may constitute plagiarism. The fact that the person who read and used the source is a different person than the one who removed the source is no excuse.

If you think there is a good book about Earthing systems, but that book was not used while writing the article, you could include it in a "Further reading" section. Jc3s5h (talk) 03:41, 3 April 2011 (UTC)

I follow what you're saying here, but I am still a little surprised to have a finger waved at me like this. I'm not interested in adding a book to the list. That's not my intention. I just saw the source listed there and noticed it was hosted by a commercial website. Personally, I always use neutral sources and I do lots of work in reducing spam. Well, I decided I would replace this commercial link with something more neutral. I did take a look at who put the www.tlc-direct.co.uk link in the article (the one I replaced) and it's Markus Kuhn and he's the primary contributor to this article. So I'm convinced that the link wasn't put there by some drive-by spammer. Anyway, I'll catch you later. Dawnseeker2000 03:54, 3 April 2011 (UTC)

You must not delete a source unless you rewrite whatever part of the article was supported by the source. If you can't figure out which part of the article was supported by the source, and you insist on removing the source, you must rewrite the entire article from scratch, without using the undesireable source. (Actually, this and several related articles such as Ground (electricity) need to be merged and rewritten.) Jc3s5h (talk) 14:26, 3 April 2011 (UTC)

Maybe then this is a good time to convert to inline references. Dawnseeker2000 15:18, 3 April 2011 (UTC)

Well, yes, but someone would have to figure out which statement is supported by which page of which source, or write it from scratch using suitable sources, which probably wouldn't be any harder. Jc3s5h (talk) 15:50, 3 April 2011 (UTC)

MEN vs TN-C-S

Early in the article the MEN is described as similar to a TN-C-S. Agreed. But then in the comparison table, the Risk of broken neutral is listed as High for TN-C-S and No for MEN. This doesn't sound right at all. As suggested earlier in the article, the multiple earthing points in a MEN system does provide a backup path for return current in the case of a broken PEN conductor (on the supply side not the neutral on the consumer side!), a risk certainly still exists. Any suggestions for a clarification? LightYear (talk) 23:46, 23 February 2012 (UTC)

After some consideration, decided to remove MEN column entirely from the comparison table. Since MEN is a combination of TN-C, TN-S and TN-C-S, the summary is different depending on which part of the network you consider. It's just too complicated to summarise unambiguously. Also makes the table suit the article - MEN is only mentioned in a couple of dot points, so to have it take up a big section of the table doesn't make sense. Column was originally added in this edit and unfortunately the editor is anonymous so can't be consulted. I don't think this will be too controversial - if the info from the column is to be retained, it should be worked into the article itself instead. LightYear (talk) 23:18, 17 April 2012 (UTC)

MEN and TN-C-S is also used in germany (required) at least since 1977. Also see DIN VDE 0100. No device is connected at the TN-C-Part of the network, this is cmpletely underground or high above in the air. which means anybody can just get in contact with the safe TN-S-Part of the system, while the TN-C-Part is in practice unreachable. Which eliminates safety differences to the TN-S System. I guess it is the same in Australia, New Zealand, Israel. — Preceding unsigned comment added by 194.25.187.119 (talk) 15:11, 4 September 2013 (UTC)

Comparison of Earthing systems

The table shows no earth electrode at site required for TN-C-S Australian wiring rules AS3000 Clause 5.1.3 Under the (TN-C-S) MEN system the neutral conductor is earthed, at source, at regular intervals, and at each electrical installation? Cotsabaca (talk) 10:09, 29 August 2013 (UTC)

Sky Voltage

"Sky Voltage" - please include a reference as this seems very dubious. 5/Nov/2015

The article sky voltage was deleted back in February as original research. I cleaned up the red links. No such user (talk) 08:11, 5 November 2015 (UTC)

Well, this "Direct connection to neutral at the origin of installation" is not an IEC terminology. IEC says that direct connection to the earthed point of the power system. I admit that regularly the neutral is the earthed point but it is not a certainty. IEC wanted to phrase it in the most possible most general way. Sztrogoff (talk) 10:02, 21 February 2016 (UTC)

Safety

In safety terms, the TT is the best. So the following report says (page 19)

ect173

--82.21.82.111 (talk) 15:29, 3 March 2016 (UTC)

Terminology

@Md iet: Please read High voltage#definition: use of terms "medium voltage" and "high voltage" depends on context. As that article says, one definition comes from system engineering: In electric power transmission engineering, high voltage is usually considered any voltage over approximately 35,000 volts. This is a classification based on the design of apparatus and insulation. Further, IEEE Std. 100<ref> ([https://books.google.com/books/about/The_IEEE_Standard_Dictionary_of_Electric.html?id=6FbxAAAAMAAJ&redir_esc=y Standard dictionary of Electrical and Electronics terms]</ref>, as well as ANSI C84.1,<ref name="Short2005">{{cite book|author=Thomas Allen Short|title=Electric Power Distribution Equipment and Systems|url=http://books.google.com/books?id=S3jLBQAAQBAJ&pg=PA234|date=29 November 2005|publisher=CRC Press|isbn=978-1-4200-3647-3|pages=234–}}</ref> defines medium voltage as "any nominal voltage greater than 1 kV and less than 100 kV." Our article also acknowledges a different definition which comes from safety point of view: The International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) define high voltage as above 1000 V for alternating current, [...] This is in the context of building wiring and the safety of electrical apparatus.

Now, since this article covers both safety and engineering aspects, either approach can be used, but please don't just go ahead and do as you please, leaving odd phrases like "high voltage systems (1 to 72.5 kV)" which are simply misleading and inaccurate. I fixed the article for now, using "your way". No such user (talk) 07:38, 13 May 2016 (UTC)

Avoid using ref tags on talk pages. — LlywelynII 02:11, 8 November 2022 (UTC)

Grounding Rod Regulations

I know Wikipedia is not a reliable source but it would still be helpful if—somewhere on or linkable from this page—we had a country-by-country list of the grounding regulations. The US seems to require an 8 foot deep spike while France seems to be fine with one 1 or 1.5 m deep. — LlywelynII 02:11, 8 November 2022 (UTC)

Electrical Earthing Hole Work

The best electrical earthing work depends on the depth of water level, if the water level of depth is 3 to 4 meters deep then the value of earthing can be up to 1 OHM 92.97.10.226 (talk) 06:08, 2 March 2023 (UTC)

Change name of “Equipment grounding”

In the subsection Equipment grounding, under the section Purposes, it seems what the current text is referring to is what’s actually called “neutral-to-case bonding” and “equipment bonding”. There’s no grounding/earthing involved. It’s used to provide a low-impedance path to clear line-to-case faults with the short-circuit protection of OCPDs (breakers and fuses), in TN-C-S and TN-C grounding/earthing arrangements like the US; see section 250.4(A)(5) of the 2020 NEC.

Also, although the NEC doesn’t define “equipment grounding” in article 100, section 250.4(A)(2) is called “grounding of electrical equipment” and pretty much defined it: “Normally non-current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equipment, shall be connected to earth so as to limit the voltage to ground on these materials.” Thus, the usage of the term “equipment grounding” in this Wikipedia article is incorrect.

So, I suggest to change the current name “Equipment grounding” to something else like “Neutral-to-case bonding.”

By the way I’m not inventing this term. It’s used by Mike Holt, for example; see https://www.ecmweb.com/content/article/20892808/the-key-to-making-proper-neutraltocase-connections. Alej27 (talk) 14:21, 13 December 2023 (UTC)

In the latest version as I write this, dated 22 September 2023, there is no section named "Equipment grounding". Jc3s5h (talk) 16:45, 13 December 2023 (UTC)

Ups. There’s no “equipment grounding” section, but there’s “equipment earthing” which means exactly the same. Alej27 (talk) 16:49, 13 December 2023 (UTC)

I suggest that "equipment grounding" does not mean the same as "equipment earthing" because the former suggests the US and the latter suggests the UK. Also, electrical codes use very careful language, so no wording change is trivial. Jc3s5h (talk) 18:08, 13 December 2023 (UTC)

But nowhere in the article is it indicated the article is for the UK, not worldwide. Only this talk page has such template. Alej27 (talk) 21:58, 13 December 2023 (UTC)

Because {{British English}} is intended only for talk pages. You've just defaced the article with it. Frankly, I don't understand the rest of this discussion, particularly the supposed distinction between "earthing" and "grounding". No such user (talk) 12:17, 14 December 2023 (UTC)

The physical reality is that "equipment earthing" and "equipment grounding" are the same thing. But various countries have different electrical legislation, with potentially incompatible plugs, sockets, and techniques. In countries where American English is spoken, the usual term is "equipment grounding" while in British English the usual term is "equipment earthing". To give you an idea of the level of detail in the legislation, the dominant electrical code in the US, the National Electrical Code, as documented in the National Electrical Code HANDBOOK, 2017 ed., (National Fire Protection Association), has 58 pages in Article 250, "Grounding and Bonding".

I looked over the section again, and I just can't figure what it is supposed to be about. I think it needs to be rewritten from scratch. Since I lack knowledge of electrical requirements outside the US, I don't feel comfortable rewriting it myself. Jc3s5h (talk) 12:34, 14 December 2023 (UTC)

The original discussion was not about the difference (if any) between grounding and earthing, it was about the fact that the subsection “Equipment earthing” has a wrong title, assuming “grounding” means the same as “earthing”.

In the first post I already explained why it’s incorrect, but I’ll do it again. “Equipment grounding/earthing” refers to connecting a ground wire between the ground terminal bar of the panel and the equipment enclosure, and then a ground rod to the ground terminal bar. However, what the subsection talks about has nothing to do with that, but with neutral-to-case bonding. “Neutral-to-case bonding” refers to connecting a ground wire between the ground terminal bar of the panel and the neutral wire. During a line-to-case fault (what the section talks about) in a TN-C-S grounding system, current does *not* through the earth ground, only through the equipment ground wire and then to the neutral wire through the neutral-to-case bond. Given this, the title of the subsection is incorrect.

But then, user Jc3s5h said in their second comment that “equipment grounding” is not the same as “equipment earthing”. So I didn’t change the title.

But now, user Jc3s5h said in their third comment that “grounding” is the same as “earthing”. So now my suggestion applies, and we shall change the title of the subsection. Alej27 (talk) 13:14, 15 December 2023 (UTC)

NEC 2017 Article 100, "Neutral Conductor" states "The conductor connected to the neutral point of a system that is intended to carry current under normal conditions." So it is wrong to say that the case is connected to the neutral wire; the case is connected to the "Grounding Conductor, Equipment (ECG)" defined in the same article as "The conductive path(s) that provides a ground-fault current path and connects normally non-current-carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both. Informational Note No. 1: It is recognized that the equipment grounding conductor also performs bonding."

Could you please explain how the NEC definition of neutral conductor implies the neutral is not connected to the case? However, regardless of that, section 250.24(C) of the 2023 NEC requires the neutral service conductor to be connected to the enclosure of the service disconnect (a.k.a. service disconnecting means or service equipment, e.g. first main circuit breaker or first main knife switch); this establishes a neutral-to-case bond at the service disconnect. Here's a quote:

(C) Main Bonding Jumper. For a grounded system, an unspliced main bonding jumper shall be used to connect the equipment grounding conductor(s) and the service-disconnect enclosure to the grounded conductor [neutral wire] within the enclosure for each service disconnect in accordance with 250.28.

Alej27 (talk) 19:28, 15 December 2023 (UTC)

The neutral conductor is intended to "carry current under normal conditions". In the US, it is usually has white insulation, and it is only connected to ground at the service disconnect. All along the path from the service disconnect to the equipment, it is kept insulated from other conductors, and it is kept insulated from the case. If the case of the equipment is conductive, it is connected to the equipment grounding conductor, which leads to the outlet. There is a fault path from the outlet back to the service disconnect, which might consist of the metallic conduit that protects the wires, a bare ground wire, or a green insulated wire. These conductors only carry current if there is a fault. Jc3s5h (talk) 19:54, 15 December 2023 (UTC)

I know everything you’re saying, yet I don’t see how you’re contradicting my comment —and section 250.24(C) of the 2023 NEC— (by stating the neutral is not connected to the case at the service disconnect). Please read the quote from the NEC in my previous reply.

I also know the neutral wire is required to be grounded (section 250.20(B)(1), 250.26(2), 250.24(A) and 250.24(A)(1) of the 2023 NEC.) But I’m not arguing about system grounding; I’m arguing that what section “Equipment earthing” describes is not equipment earthing, but “neutral-to-case bonding” (and “equipment bonding”).

Here’s an image showing the neutral-to-case bond at the service disconnect: https://global.discourse-cdn.com/internachi/original/3X/f/2/f27aca6badeafd08cb3c8e52dcfe477159ce2bba.jpeg. I hope you can now agree the neutral is bonded to the case at the service disconnect.

Now that hopefully you agree the neutral must be bonded to the service disconnect case in the US (or any other country governed by the NEC like Venezuela), I want to illustrate how line-to-case faults are cleared even if the equipment nor the system are grounded (which is what the section “Equipment earthing” talks about).

The following figure shows a split-phase (single-phase three-wire) system, under a line-to-case fault at a load, with neutral-to-case bonding at the service disconnect and equipment bonding. There’s no system (neutral) grounding nor equipment grounding anywhere in the system, since there’s no connection to the earth ground. Because the neutral is bonded to the case, the fault current can flow back to the source. And because the path it takes consists only of wires, this path has low impedance, which causes a high current, and so the OCPD (circuit breaker or fuse) trips and clears the fault.

Split-phase system under line-to-case fault with neutral-to-case bonding at the service disconnect and equipment bonding

The following figure shows the same scenario but without neutral-to-case bonding anywhere in the system. Because the neutral is not bonded to the case, no fault current can flow back to the source. So all casings (normally-noncurrent-carrying conductive/metallic parts and wires) become and stay energized, which is a hazard to people. And even if the system was grounded at the source and customer (and hence the equipment was also grounded indirectly), current could flow through the earth ground, but this path would not have a low impedance and would not clear the fault; even the NEC doesn’t allow to use the earth ground as an “effective ground-fault current path” (see last sentence of section 250.4(A)(5).)

Split-phase system under line-to-case fault without neutral-to-case bonding and with equipment bonding

If you now agree that equipment grounding is not necessary to clear line-to-case faults, we can proceed to change the title “Equipment earthing” to “Neutral-to-case bonding.” Alej27 (talk) 02:11, 17 December 2023 (UTC)

"I hope you can now agree the neutral is bonded to the case at the service disconnect." No. The neutral is bonded to ground, or earth, at the service disconnect. The case of the light fixture is bonded to the equipment grounding conductor and is insulated from the neutral conductor. Jc3s5h (talk) 03:37, 17 December 2023 (UTC)

Yes, the neutral wire must be grounded at the service disconnect, though in the last two figures of my previous reply it is not grounded.

Yes, the case of the light fixture must be bonded to the ground terminal bar, by using the equipment grounding conductor in between the two.

And yes, the neutral wire must be isolated from the case in the load-side of the service disconnect (at the light fixture).

But also the neutral wire must be bonded to the case of the service disconnect. This is explicitly stated by the 2023 NEC on section 250.24(C), as I previously highlighted in italics text in the quote. And this is what the “main bonding jumper” does. What do you not understand? Alej27 (talk) 03:57, 17 December 2023 (UTC)

References

Poor TN diagrams

While the TN-S and TT diagrams are fine, the TN-C and TN-C-S diagrams are problematic.

The TN-C diagram is supposed to depict a combined PE+N conductor for both the supply and installation wiring (no separation at all), but PE and N are shown as separate conductors in part of the diagram.

With the TN-C-S diagram, there's no PEN label. Also, typically when I see diagrams like this, the horizontal lines represent shared supply lines, while the vertical lines depict connections to a single consumer installation. So with that view of the diagram, the PEN split seems to be occurring at some random point part-way along the shared supply line prior to the individual branch connection to this one property. Weird. Technically a split anywhere along the supply fits the definition, but typically in the UK at least the split happens where the supply enters the property, and that's the configuration I'd expect to be depicted here.

Additionally the label of 'consumer' vs. the textual description of 'consuming device' isn't great.

The diagrams in 312.2.1 of BS7671:2018+A2:2022 make things very clear by simply using a box with dashed lines marked 'consumer installation', enclosing the box here labelled 'consumer', which they call 'equipment'; horizontal and vertical lines are as just described, shared and single-consumer branch wires respectively; the consumer lines enter the box depicting the consumer installation and then proceed on to the inner 'equipment' box. For TN-C-S a connection between the equipment box and the neutral supply wire is shown within the consumer installation box. I suggest that the diagrams are reworked in this fashion. DiscreetParrot (talk) 06:03, 19 December 2024 (UTC)

PE conductor cost

Why does the TN/TT/IT comparison table list the PE conductor cost for TN-C as 'least', TN-C-S as 'high' and TN-S as 'highest'? This seems dubious.

With TN-S it's normal, at least in the UK, for the steel armouring of the supply cable to be used as the earthing conductor, at least for premises supplied by an underground cable as typical in an urban setting. The cable I expect would be an armoured 2-core (single-phase) or 4-core (three-phase).

With TN-C-S, would they not likely just use exactly the same cable (in an urban underground situation) as TN-S, bonding the armouring only at the supply end and bonding the neutral instead at the consumer end, thus having the same cost. Or would they ever perhaps use a single-core (single phase) or three-core (three phase) armoured cable for underground urban connections, with the armour being the PEN?? In which case the cost may be somewhat less than TN-S. In a rural overhead scenario you might just simply be connected to two/four overhead cables, with zero PE cost, though you'd likely also have an earth electrode.

With TN-C, well that's outlawed in the UK, so...

With TT if it happens to be an underground connection then again they'd probably use exactly the same armoured cable as with TN-C/TN-C-S, just without bonding the consumer earthing to it at all, instead having an earth electrode. So little to no cost difference, right? If overhead cables then again no PE cost except the earth electrode, just as with overhead TN-C-S.

And IT would be what, essentially the same as TT?

Additionally I've just read the text under Properties > Cost, which is such a poor overview of things it simply deserves deletion, which I may do in a moment. DiscreetParrot (talk) 09:06, 19 December 2024 (UTC)