SELV a definition?

[ARWadsworth]

Is it just me that believes that the S stands for separated not safety?

I had a good argument today in a lighting shop with a shop assistant today whilst helping my Mum buy some new lights for her bathroom. The assistant said S was for safety and produced fitting documents from lots of lights in the shop to prove he was correct, I only had the 16th edition (pg25 blue cover) to show him that it means seperated.

A quick look on Google shows even vent-axia are using the word safety not seperated on their SELV equipment.

Has the 16th edition gone out of date?

Adam

[John Rumm]

Page 18 of my on-site guide (brown cover inc ammendments 1 & 2) defines it as "separated"

[charlieB]

SELV is Safety Extra Low Voltage - the shop assistant is correct.

the light or light fitting will be assessed to a prodcut standard for compliance with relevant European Directives before being CE marked.

Typical Definition: SELV CIRCUIT: A SECONDARY CIRCUIT which is so designed and protected that under normal operating conditions and single fault conditions, its voltages do not exceed a safe value.

i.e. secondary circuit seperated from hazardous circuit, such as mains, by basic insulation and earth or double/reinforced insulation where the voltage does not exceed 42.4V ac pk or 60V dc.

regards Charlie

[Andrew Gabriel]

It has changed. It used to be "Safety", but it is now "Separated". IIRC, this changed at least 10 years ago, I think when PELV was introduced.

No -- it's the other way around -- the instructions and the shop assistant were out of date.

[Dave Plowman (News)]

The warning symbol on my Fluke DVM comes on at approx 30v DC...

[Ian Stirling]

30VRMSAC = 42.4V peak - which is probably where the confusion comes in.

[ARWadsworth]

Has anyone got the red covered 16th edition they could look in please?

Adam

[Christian McArdle]

I don't know, but it concurs with Wikipedia:

(The term Safety Extra Low Voltage can still be encountered in some older publications. The modern IEE/IEC term Separated Extra Low Voltage clarifies the distinction between SELV and PELV circuits better.)

Christian.

[Owain]

Red covered, 1991 edition coming right at ya. (And it cost £34, I noted inside the cover. This was also from before it became a BS in 1992.)

Definitions -

Functional extra-low voltage - any Extra-low voltage system in which not all of the protective measures required for SELV have been applied.

No entry for Protective ELV.

Safety service - An electrical system for electrical equipment provided to protect or warn persons in the event of a hazard or essential to their evacuation from a location.

SELV - An Extra-low voltage system which is electrically separated form Earth and from other systems in such a way that a single fault cannot give rise to the risk of shock.

Section 411-02 simply refers to "Protection by SELV" and "the supply shall be from one of the safety sources listed in 411-0-02"

And having been referring to this book for 15 years I have only this minute noticed the erratum on p. 266.

Owain

[ARWadsworth]

Thanks for that.

Adam

[ARWadsworth]

You are a star. So back in 1991 it was definately seperated. Thanks.

And the erratum on p. 266 says? I must know.

Adam

[Owain]

Page

[Andrew Gabriel]

The Green 1992 edition (Amendment 1) includes PELV. That's the oldest 16th Edition I can still find (into which I had painstakingly inserted all the Amendment 2 changes).

[Den Corfield]

[Andy Wade]

Yep, the change came with Amendment 1 to BS 7671:1992, which was issued on 15th Dec. 1994. This amendment also introduced PELV and FELV.

The 15th Edition talks of Safety ELV, whereas the first printing of the

16th and the first release of BS 7671 appear to avoid the issue by using the SELV abbreviation only without giving an expansion. Clearly this was brewing in CENELEC for a while before it hit the streets...

I am reliably informed that the 17th edition (BS 7671:2008?) is now being drafted, for release during 2008. This will require increased use of RCDs - on "all" socket circuits apparently, and it's rumoured that mains-voltage socket-outlets (other than shaver points) will be allowed in bathrooms...

[Christian McArdle]

Even on dedicated freezer circuits?

Christian.

[Andy Wade]

Pass - I've told you all I know at the moment.

[ARWadsworth]

Thanks Andy. Very informative as usual. If you are correct I can already visualise the posts already that will appear here in 2008.

Adam