Smells of them having to lift the supply neutral to the input of the UPS stacks. This would require a shutdown of the entire eqipment if the Natural earth bond needs to be split for whatever reason. (Although I have done a temporary bond in DC's before to keep the UPS array going but a lot of engineers get skittish about that especially if HV is involved)


On 10/8/17 1:22 pm, Jared Hirst wrote:
Hi Simon,

Maybe it could be helpful to the Ausnog list to point us to that law you refer too?

As I personally have never heard or seen this done in any DC in Australia, or the world in the past 15 years I have been housing gear in Data Centres.

I agree that gear should have 2N, and it doesn’t affect me, but there are people that have equipment that have single fed devices, and I believe you don’t allow self installed STS devices to be installed? I could be wrong.

In any case, it would be interesting to see the law the requires you to shut down boards.


Jared Hirst
Servers Australia Pty Ltd
Phone: +61 2 8115 8801
Email: <>
*From:* AusNOG <> on behalf of Simon Cooper <>
*Sent:* Thursday, August 10, 2017 8:39:13 AM
*Subject:* Re: [AusNOG] NextDC Melbourne - Scheduled Power Maintenance - 15th August
Thanks guys, appreciate the feedback.

At NEXTDC we work very hard to keep critical infrastructure maintenance that impacts racks or the environment within the data hall to an absolute minimum.

However, some works are required to happen from time to time by law and one of those activities is a de-energisation and inspection of each of our major switchboards. This is all about ensuring that the electrical system is safe, and is an unavoidable piece of work. Rightly so.

Every rack in a NEXTDC data centre has 2N power feeds offered to it, and we highly recommend that they are used for every device in the rack. This occasional maintenance is one of the many reasons we provide this capability. Any device using the 2N supplies (aka A & B feeds) will simply see its power swing from one feed to the other. Any rack that is drawing no more that its contracted power level will have no issue when all devices move from A to B or vice versa.

Our notifications were made well in advance, as we want to give customers time to consider the management of these works and we don't assume that every rack is perfectly deployed: We are here 24/7 to assist customers with rack inspections or specific circuit down tests or maybe a controlled move prior to the day (e.g. for devices that are single fed).

Also, as we work though those discussions with customers we understand the timing in relation to their businesses, and we work very hard to coordinate schedules despite each switch board supporting many different customers and customer instances across the data centre. Occasionally that means we have to make a difficult decisions which may result in schedule changes. When that does happen, we do not compromise our notification periods.

I'll be happy to discuss these works with anyone - probably best offline or on the phone - but trust me when I say we are doing our absolute best to keep your data centre operating safely and reliably for many years to come.


    -----Original Message-----
    *Sent:* Thu, 10 Aug 2017 05:39:02 +1000
    *Subject:* Re: [AusNOG] NextDC Melbourne - Scheduled Power
    Maintenance - 15th August

    This seems reasonable? As long as no single Data Hall has both A
    and B feeds removed simultaneously, that seems normal. Doing B on
    Hall 2 and A on Hall 3 on the same day does seem slightly
    adventurous, but not entirely unreasonable (mostly in terms of if
    something goes bad in both, staff get stretched thin remediating

    A and B feeds are designed to provide redundancy to equipment,
    allowing one feed to fail and systems to continue on the other.
    Anything mission critical should be able to draw from either feed
    as required (dual PSU), and if there is a power deficit on one
    feed (causing circuits to trip), that would imply the circuits are
    incorrectly sized?

    In addition, anything mission critical with a single power supply
    would be on an ATS you would assume, or a pair of equivalent
    devices installed with one on each rail?

    Things break in datacentres, planned maintenance happens
    sometimes, better than no maintenance at all :) The fact they are
    notifying you is better than not, and it being scheduled is
    probably still better than unscheduled :) (easier to ensure
    sufficient staffing to keep a close eye on things)


    On Wed, Aug 9, 2017 at 3:43 PM, Shaun McGuane
    < <>> wrote:

        Here is the entire scheduled maintenance windows for all the
        halls we occupy.

        DataHall 2

        A Feed - Tuesday 8th August 2017 07:00 UTC +10 until 16:00 UTC
        B Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00
        UTC +10.

        DataHall 3

        A Feed - Tuesday 15^th  August 2017 07:00 UTC +10 until
        16:00 UTC +10
        B Feed - Monday 14^th August 2017 07:00 UTC +10 until
        16:00 UTC +10

        DataHall 4

        B Feed - Tuesday 15th August 2017 07:00 UTC +10 until 16:00
        UTC +10.

        ·So looks like no power on 3 data halls B feeds on the same day.

        ·Data Hall 2 was scheduled for A rail on the 8^th of August
        but has been re-scheduled with no new date of works.

        ·Data Hall 3 was scheduled for A rail on the

        Problem is that I have 3x separate dates on 3 separate e-mails
        for Data Hall 3 and I have requested a revised clarification

        Just now on the above as there has already been re-schedules
        for Data Hall 2 and 3.

        This feels like it’s going sideways and it has not even started.



        *From:*AusNOG [
        <>] *On Behalf Of *Murat
        *Sent:* Wednesday, 9 August 2017 3:20 PM
        *To:* Matthew VK3EVL <

        *Subject:* Re: [AusNOG] NextDC Melbourne - Scheduled Power
        Maintenance - 15th August

        We have been told only Feed B in Data hall 2 will be effected
        as per original schedule and Feed A is yet to be rescheduled.


        *Murat Sener*Datacentre Manager

        *PREMIER*Technology Solutions
        *P. *1300 76 76 48 *F. *1300 76 76 49 *M. *0450 604 350

        *How am I doing? Let us know!*












        *From:*AusNOG [
        <>] *On Behalf Of
        *Matthew VK3EVL
        *Sent:* Wednesday, 9 August 2017 3:13 PM
        *To:* <>
        *Subject:* Re: [AusNOG] NextDC Melbourne - Scheduled Power
        Maintenance - 15th August

        What about both feeds happening on the same day at the same time?

        On 9/08/2017 2:55 PM, Shaun McGuane wrote:

            HI Damien,

            My apologies that’s correct – but isn’t anyone concerned
            about the works being completed during business hours?

            What about increased loading of the active rail once one
            of them is switched off for these works?



            *From:*Damien Gardner Jnr []
            *Sent:* Wednesday, 9 August 2017 2:39 PM
            *To:* <>
            <> <>
            <>; Shaun McGuane
            <> <>
            *Subject:* Re: [AusNOG] NextDC Melbourne - Scheduled Power
            Maintenance - 15th August

            It says 7am -> 4pm in what you quoted? (UTC+10 is AEST)

            On Wed, 9 Aug 2017 at 2:36 pm, Shaun McGuane
            < <>> wrote:

                HI Noggers,

                Has anyone seen this scheduled maintenance
                notification happening next week?

                They maybe upgrading feeds or boards throughout the
                datacentre – has everyone seen this notification of works?

                It appears to be happening starting 5PM through to 2AM
                AEST for all Datahalls on the same date.

                NEXTDC M1 Melbourne data centre, with the assistance
                of specialist contractors, will conduct offline
                preventative electrical maintenance work on
                high-voltage and low-voltage main isolators. This will
                affect A and B feeds to the racks in Data Hall
                2/3/4 on the 15th of August.

                A Feed - Tuesday 15th August 2017 07:00 UTC +10 until
                16:00 UTC +10.
                B Feed - Tuesday 15th August 2017 07:00 UTC +10 until
                16:00 UTC +10.

                *HOW AM I AFFECTED?*
                Due to the nature of the work a single feed will be
                removed as per the dates and times above. We recommend
                that customers balance the power between both power
                rails to minimise impact during this period. If you
                have single feed devices we recommend you:



                AusNOG mailing list

            Damien Gardner Jnr
            VK2TDG. Dip EE. GradIEAust
   <> -
            We rode on the winds of the rising storm,
             We ran to the sounds of thunder.
            We danced among the lightning bolts,
             and tore the world asunder


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