Talk:Extra-low voltage

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ELV entry is a mess of standards[edit]

This entry is a misleading pigs breakfast of standards. The introduction needs to be made more generic (which I've tried to do), then later being broken down to various acknowledged standards... Otherwise it is pointless. — Preceding unsigned comment added by (talk) 10:18, 24 July 2016 (UTC)Reply[reply]

Should SELV be "Separated" or "Safety" Extra Low Voltage?[edit]

IEC refer to "Safety" exclusively. See the glossary definitions here: [1]

The IEE wiring regulations (BS7671) refer to "separated". Wheatpark 11:16, 29 June 2006 (UTC)Reply[reply]


I got the impression that at least newer IEC standards no longer claim that SELV is an acronym of any particular sequence of words. The idea that "SELV" means just "SELV" has the advantage of working in any language. Markus Kuhn 11:29, 29 June 2006 (UTC)Reply[reply]

SELV Voltage[edit]

I have a copy of EN60950 in front of me, it is old, but it states in "section 2.3.2 Voltages under normal conditions" that the voltage shall not exceed 42.4V peak or 60Vdc. Sure anyone doing any work from a safety point of view would not be referring to Wikipedia as an authoritative source, but this is an important value. Has this been increased to < 50V or is the statement in error. Cheers, PaulE. —Preceding unsigned comment added by (talk) 05:03, 2 July 2010 (UTC)Reply[reply]

IEC 61010-1:2010 (3rd Edition) still says 42.7Vpk/60Vdc.Jeffrobins (talk) 09:28, 11 February 2012 (UTC)Reply[reply]
There are different voltages per different standards. For example its 50V ac and 120V ripple free dc for IEC 61347 series. (talk) 04:27, 13 September 2015 (UTC)Reply[reply]


The entire introduction is confusing and contradicts itself. The intro states that ELV is less than 50V AC and 120V DC and then in the next paragraph says that it's less 1000V AC and 1500V DC. I can't really comprehend why an organisation would consider 1000V "low". The statements about IEC terminology 'low voltage' and common usage are just confusing. Can someone rewrite the introduction? -- (talk) 21:51, 14 January 2008 (UTC)Reply[reply]

I've had a go at the introduction. There are various standards around the world, but they are beginning to harmonise. ELV is a general definition defined as a maximum voltage a.c and d.c. A designer can pick and choose what they want 12v d.c., 24v d.c. 50v a.c. etc. So long as it's under the prescribed 50v a.c. and 120v d.c. - thus the confusion. There are also "recommendations" when areas are more conductive or dangerous. <1000v a.c. and <1500v d.c. are considered "low voltage" when comparing with lightening / Tesla / distribution type voltages e.g. 11,000v a.c., 33,000v a.c. or the super-grid 400,000v a.c. This is high voltage does: — Preceding unsigned comment added by (talk) 13:19, 24 July 2016 (UTC)Reply[reply]

I've added a table that more clearly displays the three official and widely used voltage-range definitions for electrical safety on all three articles on the subject. Better now? Markus Kuhn (talk) 20:17, 15 January 2008 (UTC)Reply[reply]
UK mains voltage (230/240VAC) used to be described as "medium voltage". Is this term no longer used? Biscuittin (talk) 08:59, 10 April 2009 (UTC)Reply[reply]
A word means what you say it means, like Humpty Dumpty always said...but in my limited experience of electrical engineering, no-one in the power distribution business calls 240 v a 'medium' voltage. --Wtshymanski (talk) 16:39, 20 December 2009 (UTC)Reply[reply]


Is this the "razor-only" two-prong outlet in some old homes and public washrooms ? (talk) 11:37, 20 December 2009 (UTC)Reply[reply]

No. 120 volts is not extra-low voltage. Our knowledgeable world-wide contributors will tell us if isolated shaver outlets were ever used outside of North America. --Wtshymanski (talk) 16:39, 20 December 2009 (UTC)Reply[reply]
The UK has isolated shaver outlets, powered at nominally 230 volts, the same as normal house power. (I have just measured the house voltage and it came to 240 V pretty much bang on, though of course it does vary.) No other outlets are allowed in bathrooms, unless at least 3 metres from a bath or shower. Uncriticalsimon (talk) 22:10, 19 March 2021 (UTC)Reply[reply]

Less than 50 or 25 Vrms?[edit]

The text says ELV is < 25 V AC, but the table says < 50 V AC. The text says < 60 V DC, but the table says < 120 V DC. Why the inconsistency? From other sources, it seems that 50/120 are the right values but there are some restrictions on voltages between 25/60 and 50/120. KenShirriff (talk) 06:31, 13 May 2012 (UTC)Reply[reply]

Lethal Voltage[edit]

The ELV voltage values in the table are incorrect at: "Extra-low voltage (supply system) < 50 Vrms < 120 V". The basic foundation for all these "ELV", "SELV" levels it what is considered a lethal voltage, which has always been in the order of 50V a.c. or 70 V d.c. but depending on circumstances (dry or wet conditions). The specific voltage is linked to the human body resistance and therefore what is a dangerous current under shock conditions. As the old saying goees: "It's the Volts that jolts, but the mills (milliamps) that kills". Q-462 (talk) 12:16, 6 November 2012 (UTC)Reply[reply]

SELVEL appears to be first used here?[edit]

I have not previously come across SELVEL and can not find any reference to it on the WWW or in standards. The levels quoted are 'Hazardous Energy Levels' (from 60950?) but the term SELVEL is not widespread if it is used. Rolinger (talk) 15:58, 23 June 2015 (UTC)Reply[reply]

Add 48 VDC Server Power Distribution[edit]

Someone should add 48 VDC server power distribution to this article. Google joined the Open Compute Project to drive a migration toward 48 VDC standard in IT infrastructure. • SbmeirowTalk • 05:07, 10 March 2016 (UTC)Reply[reply]

EU's Low Voltage Directive[edit]

A reasonable inference from the inclusion of a reference to the EU's Low Voltage Directive in the lead paragraph is that it is somehow relevant to the subject. The paragraph said, "EU's Low Voltage Directive applies from 50 V a.c. or 75 V d.c.".

This is ambiguous - it does not say in which direction (up or down) from these voltage levels it applies. It might be inferred from the article name ("Extra-Low Voltage") that this 'obviously' means from these voltages down to zero.

However, according to the linked Wikipedia article by that name, Low Voltage Directive, "The directive covers electrical equipment designed for use with a voltage rating of between 50 and 1000 volts for alternating current (AC) or between 75 and 1500 volts for direct current (DC)." This seems to be (exactly for a.c. and approximately for d.c.) the voltage range that is NOT considered ELV - certainly by the IET definition quoted in the same paragraph: "electrical potential . . . does not exceed 50 V a.c. or 120 V d.c."

To some extent this confusion might be alleviated by the table defining High voltage, Low voltage and Extra-low voltage opposite the lead text, however, the exclusion of the EU directive's 75V d.c. level from the table and it's apparent disagreement with IEC's and IET's lower bound of 120V d.c. does not help.

Is the EU's Low Voltage Directive actually relevant or helpful here, therefore?

In order to remove the ambiguity and so avoid 'wrong-footing' the reader into making the 'obvious' but incorrect assumption, above, I have edited the sentence on the Low Voltage Directive in this article to explicitly state the upper voltage bounds of the directive's applicability.

Would an editor with sufficient subject knowledge please assess the relevance of the Low Voltage Directive to this article and if the opinion is that it is relevant, add some few words to show how it (implicitly or explicitly) defines or is relevant to ELV as opposed to LV or otherwise remove the sentence, which, to me, seem to add nothing but irrelevance and confusion? Hedles (talk) 11:31, 21 April 2019 (UTC)Reply[reply]

I think mention of the LV should not be in the lede since the article is about ELV. However some words to set it off such as "in contrats, the LV directive ... ". Constant314 (talk) 18:22, 21 April 2019 (UTC)Reply[reply]