If an RCD used in NZ is labelled as being Type AC, however passes a test when tested as Type A does it comply?
8.3.10.2 note 1 If the RCD being tested is marked with the symbol confirming that it is a Type A RCD, the residual direct pulsating current testing may be omitted.
Is this note implying an RCD marked other than Type A can be used, but it just needs to be tested for residual pulsating DC?
Type A & Type AC RCDs
Re: Type A & Type AC RCDs
2.6.2.2 explains about types of RCD, type AC RCD's dont comply with NZ requirements
Re: Type A & Type AC RCDs
Thanks for the reply. Yes, I understand type A must be used in NZ. The reason I asked the question, is I came across a site where type AC had been recently installed, however they passed when being tested as type A.
I agree with you, but 8.3.10.2 note 1 had me scratching my head a bit. Not sure why that would be mentioned, unless you can use an RCD marked differently to type A, as long as it passes a type A test. It’s basically saying pulsating DC test can be omitted if marked type A, it kind of implies an RCD labelled differently can be used, it must just pass the pulsating DC test.
I’m more talking about the marking on the device, I understand the characteristics must operate as type A. It was suggested to me that perhaps they’re all made identical on the same assembly line, but just marked differently depending on their destination.
I agree with you, but 8.3.10.2 note 1 had me scratching my head a bit. Not sure why that would be mentioned, unless you can use an RCD marked differently to type A, as long as it passes a type A test. It’s basically saying pulsating DC test can be omitted if marked type A, it kind of implies an RCD labelled differently can be used, it must just pass the pulsating DC test.
I’m more talking about the marking on the device, I understand the characteristics must operate as type A. It was suggested to me that perhaps they’re all made identical on the same assembly line, but just marked differently depending on their destination.
Re: Type A & Type AC RCDs
No, they are definitely NOT made the same & just marked different.
There are particular tests - way more than a simple field test - set out in the relevant product Standards (which are cited in "3000").
The difference between what's required in Oz and what's required for NZ is that in NZ RCDs have to operate on pulsating d.c. fault current waveforms as well as on sinusoidal waveforms.The requirement is set in 2.6.2; and it's full compliance with the relevant product standard, not simply passing a field test. The fact that a particular model of Type AC trips when field-tested on d.c. doesn't (can't) show full compliance with the specifications for Type A. There's no way any field-testing regime can replicate the conditions for confirming product compliance.
And the reason 8.3.10 specifically doesn't require a d.c. test for marked RCDs is because the whole of Section 8 is about checking the installation work; and not about checking product compliance. Section 8 matters include that an appropriate product has been selected, and that it has been installed correctly. Product compliance has nothing to do with it.
If it's clearly marked as Type AC, then it's obvious that it does not meet the NZ requirement; regardless whether it may pass a (limited) field test.
In the absence of marking (eg marking no longer legible on re-used RCD), a field test gives (very) limited conformation of d.c. operation - but this is based on the supposition that the RCD was Approved for sale in NZ originally, and would therefore have complied.
(Provided it's tested with both polarities - I've had lots of Type ACs that operate on one polarity but not on the other; which is probably due to the internal hold-in magnet being reinforced on one polarity instead of being over-come).
So the issue of whether the RCD has been correctly selected (is of an acceptable type) is primarily a matter for visual inspection; IE if the clause calls for a particular Type, and the product is marked as being that Type; then correct selection can be conformed; and the testing only needs to prove correct installation.
Which is more than simply noting that the RCD trips when the button is pressed: the required result is that we must prove isolation of the circuit (in all poles required to be isolated).
Both these points have been clarified in 2018 edition; which makes no mention at all of doing any d.c. test.
2018 edition simply states, if not clearly marked as acceptable type, replace it.
Worth noting that the NZ requirement in "3000 " is not "Type A" ; because that would prohibit the use of RCDs with improved performance under adverse circuit conditions - such as Types B or F; which both have the performance of a Type A plus some additional capabilities.
Some of the "companion" Standards, such as '3001" do specify Type A, but current revisions will change that wording (see the drafts currently open for Public comment).
Also worth noting that Oz is preparing to follow NZ down the 'don't choose type AC' path; starting with these companion Standards and eventually for "3000" as well.
Similarly there's no requirement to test operating times under Section 8. Again, operating time is a mater of product compliance, and that's not what Section 8 is about.
Some standards do (currently) require operating time tests for periodic verification; but for most situations the main thing is simply to ensure that the mechanical side of the device hasn't seized up. If it works at all, it'll work within time.
There are particular tests - way more than a simple field test - set out in the relevant product Standards (which are cited in "3000").
The difference between what's required in Oz and what's required for NZ is that in NZ RCDs have to operate on pulsating d.c. fault current waveforms as well as on sinusoidal waveforms.The requirement is set in 2.6.2; and it's full compliance with the relevant product standard, not simply passing a field test. The fact that a particular model of Type AC trips when field-tested on d.c. doesn't (can't) show full compliance with the specifications for Type A. There's no way any field-testing regime can replicate the conditions for confirming product compliance.
And the reason 8.3.10 specifically doesn't require a d.c. test for marked RCDs is because the whole of Section 8 is about checking the installation work; and not about checking product compliance. Section 8 matters include that an appropriate product has been selected, and that it has been installed correctly. Product compliance has nothing to do with it.
If it's clearly marked as Type AC, then it's obvious that it does not meet the NZ requirement; regardless whether it may pass a (limited) field test.
In the absence of marking (eg marking no longer legible on re-used RCD), a field test gives (very) limited conformation of d.c. operation - but this is based on the supposition that the RCD was Approved for sale in NZ originally, and would therefore have complied.
(Provided it's tested with both polarities - I've had lots of Type ACs that operate on one polarity but not on the other; which is probably due to the internal hold-in magnet being reinforced on one polarity instead of being over-come).
So the issue of whether the RCD has been correctly selected (is of an acceptable type) is primarily a matter for visual inspection; IE if the clause calls for a particular Type, and the product is marked as being that Type; then correct selection can be conformed; and the testing only needs to prove correct installation.
Which is more than simply noting that the RCD trips when the button is pressed: the required result is that we must prove isolation of the circuit (in all poles required to be isolated).
Both these points have been clarified in 2018 edition; which makes no mention at all of doing any d.c. test.
2018 edition simply states, if not clearly marked as acceptable type, replace it.
Worth noting that the NZ requirement in "3000 " is not "Type A" ; because that would prohibit the use of RCDs with improved performance under adverse circuit conditions - such as Types B or F; which both have the performance of a Type A plus some additional capabilities.
Some of the "companion" Standards, such as '3001" do specify Type A, but current revisions will change that wording (see the drafts currently open for Public comment).
Also worth noting that Oz is preparing to follow NZ down the 'don't choose type AC' path; starting with these companion Standards and eventually for "3000" as well.
Similarly there's no requirement to test operating times under Section 8. Again, operating time is a mater of product compliance, and that's not what Section 8 is about.
Some standards do (currently) require operating time tests for periodic verification; but for most situations the main thing is simply to ensure that the mechanical side of the device hasn't seized up. If it works at all, it'll work within time.
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Re: Type A & Type AC RCDs
Hi,TPower wrote: ↑Fri Jun 12, 2020 12:49 pmIf an RCD used in NZ is labelled as being Type AC, however passes a test when tested as Type A does it comply?
8.3.10.2 note 1 If the RCD being tested is marked with the symbol confirming that it is a Type A RCD, the residual direct pulsating current testing may be omitted.
Is this note implying an RCD marked other than Type A can be used, but it just needs to be tested for residual pulsating DC?
No you can't read the clause in reverse unless it is also printed in the standard that way.
In any case in New Zealand, If it was used as an RCD as required by AS/NZS 3000 (for example on domestic sub circuit supplying socket outlets) the Regulations deem it to be unsafe just for the marking.
Therefore it is an offence for the owner to allow anyone to use the installation as the installation is unsafe.