EL-installasjon Forskrifter, Lover & Regler
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Question about Iz > I2 in 'Forskrift om elektriske lavspenningsanlegg'
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Hello,

Apologies for writing in English - my Norwegian isn't good enough! Hope it's OK and thanks to anyone who takes the time to read and respond. Respond in Norwegian if you prefer and I can read with the help of google translate, and maybe improve my Norwegian!

I'm an electrical engineer with some experience in LV installation also. Back in UK I was approved by my local authority as an electrician, and I'm trying to get the dispensation here just to work on my own home, but expect DLE will reject! :) Anyway that's another story. Whatever the outcome I want to be fully knowledgeable of the Norwegian standards and am studying NEK 400, etc.

I have a question about the wording in 'Forskrift om elektriske lavspenningsanlegg' of this section...

Ved bruk av PVC-isolert kabel med små tverrsnitt skal vern mot overbelastning velges slik at
- vernets høyeste prøvestrøm I2 ikke overstiger kabelens maksimale strømføringsevne IZ eller
- vernets høyeste prøvestrøm I2 ikke overstiger høyeste prøvestrøm som er benyttet for materiell i kretsen.
Med små tverrsnitt menes tverrsnitt opp til og med 4 mm2. (NEK 400: 433.2)

The first point is very clear - simply Iz > I2, and well covered in NEK 400. Also I've now learned about the Norwegian characteristic low I2 jordfeilautomats that 'help' to comply still with sensible cables and method A. Very interesting.

The second point I dont understand. My attempt to translate would be 'the rating of the material in the circuit must exceed I2'. By 'materiell' can they mean things like the socket outlets and switches, etc? If so then that seems to imply you can not make a 16A circuit with socket outlets, light switches, etc. All the CEE 7/3 'Schukos', light switches, etc I see are rated at 16A, but you would need higher (I2) on a 16A In circuit. Surely you can make a 16A circuit with socket outlets?
So I guess I interpret something wrong. Appreciated if someone can explain. Smile

Thanks
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   #1
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Det første først. For å kunne jobbe på eget anlegg må du som du selv nevner, ha godkjenning fra DLE. Kravene godkjenning kan du lese deg til i FEK (Forskrift om elektroforetak og kvalifikasjonskrav for arbeid knyttet til elektriske anlegg og elektriske foretak). Les §§ 14 - 18, du må også oppfylle noen kriterier nevnt i FEK §§ 6 - 10.

Du skriver at du ønsker å utføre noe arbeid i din egen bolig. I Norge har vi noen særnorske regler, disse finner du i kapittel 8 i NEK400.
Dette forklares i NEK400: 823.433.1
I bolig er det enkelt og greit krav om at:
1) Ib<In
2) I2<Iz

Dette "problemet" er av enkelte produsenter for løst ved å redusere sikringen fra 16A til 15A

Håper noe er forståelig. Lykke til med godkjenning av yrket ditt =)
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   #2
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It implies that lightswitches and socket outlets has to be testet with the current on the circuit. So normally socket outlets and switches are testet with 16A.
If you work on something bigger, like a 25A circuit then you have to make sure that socket outlets are testet for 25A.
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   #3
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Correct.
We have another kind of outlet for higher currents.
On 20A and 25A we have something called “flatstift”, The pins are much bigger, and a bit flattened.

But, the “problem” with the I2<Iz in a home is still there.
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   #4
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Tusen takk for the replies! Smile

But I am not 100% sure I understand. Say I take an example circuit protected with a B16 JFA (In = 16A). In UK I can simply follow Ib <= In <= Iz, so my cable can have capacity 16A and the switches/sockets (materiell) can be rated at 16A.

In Norway it says 'vernets høyeste prøvestrøm I2 ikke overstiger høyeste prøvestrøm som er benyttet for materiell i kretsen'

I2 for a standard B16 JFA would be 1,45 x 16 = 23.2A. Even with the special Norwegian market JFA, e.g. Eaton B/C 15 with I2 value of 1.3 x In = 19.5A, or Schneider Electric with B/C 16 with I2 = 1.2 x In = 19.2A, the I2 value is still greater than 16A

So the question is, are 16A sockets, switches tested to 19.2A or more by the manufacturers?

However I note the 'or' (eller) between the two statements in 'Forskrift...' and understand this 'or' was also highlighted by DSB in Elsikkerhet #55. So if I comply with the first point for cables (Iz > I2) which is easy, I can forget about the second point for 'materiell høyeste prøvestrom'. So I think it is clear in the end. Smile

Thanks again for anyone who replied.
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   #5
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preben88 Saturday, March 26, 2016
Correct.
We have another kind of outlet for higher currents.
On 20A and 25A we have something called “flatstift”, The pins are much bigger, and a bit flattened.

But, the “problem” with the I2<Iz in a home is still there.

Det er vel egentlig ikke noe problem med I2 og 25A, går ikke krav 2 kun opp til 20A??
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   #6
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I have a 'flatstift' plug for my cooker on a 20A circuit. But I assume on a 15/16A circuit people will still use standard 16A Schuko plugs, even though I2 is minimum 19.2A. But it seems like 'vernets høyeste prøvestrøm I2 ikke overstiger høyeste prøvestrøm som er benyttet for materiell i kretsen' is optional, so that's OK.
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