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UPS powered mains sockets

Discussion in 'Electrics UK' started by gbrown100, 18 Oct 2020.

  1. gbrown100

    gbrown100

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    Hiya,

    I have a shed which will have a UPS in it, it'll run things like a 3D printer, Laptop, PS4 etc (not at the same time). I hate trailing cables... I like wall sockets! This is a £450 UPS so I don't want to waste it but only has the C13 sockets in the back of it so no 16amp out I can feed into a radial.

    Does anyone have any opinions on me outputting each UPS feed (there are 8 in the back) into a radial going to a single socket on the wall? Personally I don't see any issue other than someone coming into the shed and plugging a high consumption device in it and killing the UPS. It will be appropriately labelled and coloured differently and no-one really goes in there apart from me anyway. This is a private residence not a business.

    Any idea how best to link the two together? Would I be better off simply running a single C14 plug out of the UPS for each socket and running in flex behind the wall and straight into the socket?

    Thanks

    Graham
     
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  3. flameport

    flameport

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    These: https://cpc.farnell.com/pro-elec/pe01051/lead-iec-plug-c14-bare-ends-5m/dp/PL13267
    with the bare end connected to an appropriate socket on the wall. Shorter versions are available.

    If the flex is to be concealed in the wall, it must be installed in the appropriate zones, which are vertically or horizontally from each socket, or within 150mm of the ceiling or a corner where two walls meet.

    As for people plugging other items in - that can be avoided by using non-standard sockets and the matching plugs such as
    https://cpc.farnell.com/mk/k1257whi/1-gang-outlet-non-standard/dp/PL00681
    and https://cpc.farnell.com/mk/647whi/non-standard-13a-plug-white/dp/PL00683
    if you consider that someone connecting random kettles, toaster ovens and tumble dryers is likely to be a problem.
    Otherwise, standard sockets appropriately labelled could be used.
     
  4. Robin0577

    Robin0577

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    In the I.T. & communications environments I've worked in over the years, it has been standard practice to use bright red 13A sockets for backed up supplies. https://www.tlc-direct.co.uk/Products/AA213USR.html
    Makes them obviously different without the need for non-standard sockets.
     
  5. bernardgreen

    bernardgreen

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    May be a requirement to identify sockets supplied with 230 volts from a UPS when the supply to the property has been switched OFF at the main switch.

    If the fire brigade have pulled the DNO fuse to ensure there is no electricity in a burning house they would not be happy to find 230 volts still present in the house when they start using hose lines. Perhaps a label by the meter to advise that there are sockets fed from a UPS would suffice
     
  6. JohnW2

    JohnW2

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    Apart from being a very unlikley occurrence in your case, I think you'll find that any half-decent UPS would not be 'killed' by having a large load connected to it, even if that 'very unlikely' event ever did occur.

    Kind Regards, John
     
  7. ericmark

    ericmark

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    I did look into a large UPS for whole of an office complex, two problems, one a large UPS cost more than a load of small UPS, and two was the problem with earthing, if the supply cable is damaged with a TN-C-S supply then the DNO earth may not be at earth potential so you can't use the DNO earth for the UPS.
     
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  9. gbrown100

    gbrown100

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    Thanks all, so yes, separate sockets per C13 seems the way to go!

    Thanks @flameport, yes have done some wiring in the past and had it checked / signed off as appropriate, cables will run horizontally from the point of entry to the row of sockets.

    Thanks @Robin0577 , I found those and indeed have now ordered :) The only mains integrated UPS I have worked with have been with bypass switch in dedicated server rooms with decent wiring so always done with standard sockets and judicious labelling!

    @bernardgreen thanks for this, I have several UPS's around the house for IT / cctv and never considered this. Will label the main and shed consumer units as appropriate just in case.

    @JohnW2 about 20 years ago a St John's place I had installed IT equipment there, they had removed the warning stickers placed over an extension lead that was plugged into an APC ups and plugged a fan heater in, I guess the fuse on it was faulty as it filled the room with smoke! We were deemed to have done enough after an investigation but we changed procedures to always match the number of sockets to the devices after that.
     
  10. FrodoOne

    FrodoOne

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    An improvement to the above suggestion might be to use these (https://cpc.farnell.com/volex/152610-1/power-cord-c13-to-c14-connector/dp/PL15110?st=iec c14 c15) (or shorter) leads with a Male C14 connecter to plug into the UPS and a Female C13 connecter to "mate" with a C14 Male connector on a wall-plate.
    (If you cannot locate a wall plate with a built-in C14 connector it is easy enough to mount one or more C14 connectors on a blank wall plate.)

    In doing this you will have no problems in terminating and clamping bare wires.
     
  11. JohnW2

    JohnW2

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    Interesting. I'm rather surprised by that, even for 20 years ago. Quite apart from whatever overcurrent protection there was (or wasn't, at least, effectively!) on the output, even if that protection were absent or failed, I would have expected that an excessive load connected to the output would probably cause the oscillator of the inverter to 'stop' (hopefully in a very low current-consuming state).

    Unless something other than the fuse was also faulty, I would be tempted to call this a 'design fault'. When one designs something to supply power to a load, I would have thought one of the first issues to be addressed is how the equipment will behave if sometimes attempts to draw excessive currentr from it, ideally including the situation in which there is a single fault (like a 'faulty fuse' - albeit an extremely rare occurrence).

    Kind Regards, John
     
  12. SimonH2

    SimonH2

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    You mean, a plug to fit the UPS, length of flex, socket on wall - all repeated as many times as you need ? If you meant (and reading it again I don't think you did) several plugs, all connected to the same set of sockets - then that's a definitely no as you could unplug a plug and it will have live exposed pins :eek:
    I'd suggest just using one plug, take that to the first socket, and link along the sockets. Unless the UPS capacity is too high for one connector (unlikely for a domestic setup) then it's the neatest and cheapest way to do it.

    BTW - I've witnessed a customer calling up our helldesk and "complaining vociferously" about the "pile of s**t UPS" we'd supplied to them, "it's obviously faulty as it's got alarm lights on it and bleeping madly". Quick check of the UPS remotely, and find it's gone into bypass due to overload. Lets just say the customer "quietened down" when they realised it was their fault - yup, fan heater plugged into a socket clearly labelled "UPS supplied - IT loads only" :whistle: I think some "staff education" followed :D
     
  13. ericmark

    ericmark

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    We bought a 3 kW with 6 kW peak 12 volt inverter for a narrow boat, the kettle caused blue smoke, even when rated at 3 kW. On investigation the inverter had an array of FET's each one had a 16 amp blade fuse to both protect the FET and assist in load sharing between the FET's but there was no warning if a fuse ruptured so it was a domino effect once first fuse ruptured. Clearly a poor design, but that's the problem, until something goes wrong your unaware of a poor design.

    But the major concern was RCD protection and earthing, with the electric car getting type B RCD's is no longer a problem, they are used with most EV chargers, but at the time everything was fitted with type AC RCD's which are no good with a simulated sine wave inverter. Being a steel hull boat, the hull was a good earth, so no real problem.

    However in an office also a problem with earthing, my thoughts was, with one socket outlet only, then if supply lost, lets assume road works has hit the supply cable, then it is like a shaver socket, and each item would need two faults for there to be a real problem, but if more than one item is plugged in, then looking at earth rods etc.

    The other problem is again the RCD protection, if there is a fault, which trips the mains supply, clearly you don't want any UPS to continue supplying the faulty item. And all the UPS we had simply did not have any RCD protection, maybe that's OK in a server room, but not in the office. In the main the laptop did away with the need for UPS in the office.
     
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