Disclaimer: I don't work on data center equipment.

Article 645 from the 2014 NEC includes the 600V rating limit in the
definition for Information Technology Equipment. The 2017 NEC no longer
includes the definition for ITE in Article 645, but 2017 NFPA 75 does and
it includes the 600V limit. In general the 600V limit comes from the
traditional US delineation between low voltage and medium voltage, however
the NEC is slowly moving toward a higher delineation point, at least for
some cases. For example the 2014 NEC changed Article 490 from covering
equipment over 600V nominal to equipment over 1000V nominal. The 2014 NEC
Handbook notes that there is a coordinated effort in this regard related to
alternative energy systems. Also see 250.180 (in general Part X of Article
250), where again starting in the 2014 NEC grounding requirements for
systems over 600V was changed to 1000V. The NEC is not clear on making a
distinction between ac/rms and dc voltages where these limits are imposed,
so the limit is generally applied regardless of waveform. In any case, this
is more of an installation issue than a product certification issue, though
for US certification it should be possible to install such equipment in
compliance with the NEC. It may be helpful to have a discussion on NEC
compliance with the customer to understand how they intend the NEC to be
applied to installations with their equipment.

With regard to certification, UL 60950-1 does include the limitation of
600V for information technology equipment, however the scope (of UL
60950-1) also indicates that the standard is also applicable to external
power supply units intended to supply other equipment within the scope of
this part of IEC 60905. Arguably, this leaves room for such an external
power supply's input not to fall under the 600V limit expressed in the
earlier part of the standard as long as the ITE it supplies falls under
that limit. In any case, Note 2 under clause 1.1.1 indicates that the
standard can be applied to electronic parts of equipment even if such
equipment doesn't wholly fall within the scope. I would think you could
apply UL 60950-1, and if there are any items that are not covered by the
requirements of the standard, you could supplement with requirements from
another standard, perhaps UL 508C
<http://ulstandards.ul.com/standard/?id=508C_3>.

On Wed, Sep 21, 2016 at 8:02 AM, john Allen <john_e_al...@blueyonder.co.uk>
wrote:

> Bostjan
>
>
>
> I would seriously consider pointing out to your customer that their
> specified supply voltage is not a common one (at all) and ask them to state
> in more detail the system configuration which will provide it, and then you
> should know more clearly what you are up against and how to deal with it.
> Mention that the voltage does not appear to coincide with any
> generally-known commercial level known to be found in Europe or N.America,
> and thus ask where it will be found - suspicion might fall on some other
> country &/or an end-use customer that has some very special equipment, and
> might also point you towards some national standard(s) that could be
> national variations on known international ones.
>
>
>
> Ignorance is not a “crime” in cases like this where “something” is very
> unusual and where no-one here on this very experienced forum can provide
> any definitive, or even “educated”, guidance.
>
>
>
> John E Allen
>
> W.London, UK
>
>
>
> *From:* Boštjan Glavič [mailto:bostjan.gla...@siq.si]
> *Sent:* 21 September 2016 05:47
> *To:* EMC-PSTC@LISTSERV.IEEE.ORG
>
> *Subject:* Re: [PSES] standard for power suply for server room.
>
>
>
> Hi Ken,
>
>
>
> UL1012 has the same limitation as 60950-1.
>
>
>
> IEC 61010-1 is not OK since it is not a laboratory equipment or measuring
> equipment.
>
> IEC 62477-1 has also limitation in the scope however limits are 1000Vac
> and 1500VDC.
>
>
>
> Best regards,
>
> Bostjan
>
>
>
> *From:* IBM Ken [mailto:ibm...@gmail.com <ibm...@gmail.com>]
> *Sent:* Wednesday, September 21, 2016 6:36 AM
> *To:* Boštjan Glavič <bostjan.gla...@siq.si>
> *Cc:* EMC-PSTC@LISTSERV.IEEE.ORG
> *Subject:* Re: [PSES] standard for power suply for server room.
>
>
>
> Hi Bostjan!
>
> You might be able to use 60950 or (UL1012?) anyway; I know the scope says
> "Mains or Battery powered up to 600V", but I think the focus of that limit
> (vs the 1000V limit in the LVD for example) might be on just Mains powered
> circuits, because 600V is the delineation point between "Low Voltage" and
> "high voltage" per the National Electrical Code.
>
>
>
> On the other hand, I believe the spacing calculations go higher than 600V
> in 60950 because internal voltages can go much higher than the supply
> voltage (boost stages in a SMPS, inverters for CCFL tubes, HV supply for
> corona wire in a laser printer, TV flyback, etc).
>
>
>
> Would 61010 work?
>
>
>
> -Ken A
>
>
>
> On Wed, Sep 21, 2016 at 12:09 AM, Boštjan Glavič <bostjan.gla...@siq.si>
> wrote:
>
> Dear experts I again need your opinion on below issue.
>
>
>
> Customer was asked for development of power supply which will be used to
> supply a  server in data centre. Input to power supply is defined as
> 750VDC. Unfortunately no information is available how this DC supply
> voltage is generated and reference to PE. Most probably it will be floating.
>
>
>
> Now the problem, what standard to use for such product?
>
>
>
> -          Standard IEC 60950-1 which is most often used is limited to
> 600V rated voltage. Does it mean 600VRMS? Is it then allowed to approve
> also products with 600xsqrt(2)=848VDC  rated voltage according IEC 60950-1
> or limit is also set to 600VDC? Where this limit actually comes from? If
> you check requirements for clearance and creepage distance they go quite
> higher than 600V.
>
> -          Standard IEC 62477-1 could be appropriate standard however
> problem is that this standard is not worldwide harmonised and therefore no
> national certificates (US/CAN, China) are possible based on report
> according to this standard
>
> -          What other standard would be OK for US/CAN?
>
>
>
> I appreciate your feedback.
>
>
>
> Best regards,
>
> Bostjan
>
>
>
> -
> ----------------------------------------------------------------
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> This message is from the IEEE Product Safety Engineering Society emc-pstc
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> emc-p...@ieee.org&GT;
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> All emc-pstc postings are archived and searchable on the web at:
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> Attachments are not permitted but the IEEE PSES Online Communities site at
> http://product-compliance.oc.ieee.org/ can be used for graphics (in
> well-used formats), large files, etc.
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-- 
Scott Aldous | Regulatory Compliance Program Manager |
scottald...@google.com | 650-253-1994

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