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Inverter backup bypass

  • 02-12-2024 12:31PM
    #1
    Registered Users, Registered Users 2 Posts: 8


    Curious to know if people are installing backup bypass switches.

    A switch the can feed the essential circuits from the mains in case of inverter failure.



Comments

  • Registered Users, Registered Users 2 Posts: 12,821 ✭✭✭✭the_amazing_raisin


    I looked at this and parked it because of the hassle, didn't have the money at the time

    Basically the installer was saying they'd need to redo the meter tail due to the placement of my fuse board in the middle of the house.

    The changeover switch would need to be at the meter box and the neutral from the meter to the fuse board would need to be cut and isolated, hence a new meter tail

    As a stopgap I got them to just fit a backup power socket upstairs, it's enough to run the essentials in a power cut. I'll probably look at getting the heat pump and maybe lights and kitchen sockets added to the backup circuit in future, but it's a bit of a pain post install

    What I'll say is be absolutely sure the electrician actually runs a backup cable if you're thinking about it. The message didn't get through to the subcontractor my installer used so it'd need to be a post install job

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • Registered Users, Registered Users 2 Posts: 8 SolarBananas


    I dont think we are on the same page.

    Imagine you get your lights set up on the battery backup as essential circuits.

    Then your inverter fails, now you have dead essential circuits.
    There should be a switch to put them back onto the mains.

    At least this is my understanding of it.



  • Registered Users, Registered Users 2 Posts: 2,646 ✭✭✭SD_DRACULA


    In that case you're better off powering the whole board from the inverter backup port and if the grid dies you'd flip the changeover switch to do that, but also only switch on the "essential" circuits while making sure the inverter can provide enough power to them.

    i.e. leave off the HP, EV, shower and maybe only leave on lights, kitchen and a socket circuit.



  • Registered Users, Registered Users 2 Posts: 12,821 ✭✭✭✭the_amazing_raisin


    Yes you'd want a changeover switch. The things is the switch has to be within 2 metres of the front door or meter box so that firefighters can access it (this is what my installer told me, I'm deferring to their knowledge here)

    In my particular case this is difficult because my fuse board is in the middle of the house, so it requires a lot of new cable runs

    I think @SD_DRACULA has the right idea with a full house changeover switch. You could also have a socket on the backup supply like I do to power anything that could benefit from a UPS function, if the inverter fails then it's easy enough to plug into a different socket

    "The internet never fails to misremember" - Sebastian Ruiz, aka Frost



  • Posts: 2,768 ✭✭✭ [Deleted User]


    I did this, I have 4 circuits that get permanently fed from the inverter, bedroom sockets (upstairs office), heating, fridge, lights and living room, wifi is on it too. Herself doesn't even notice that there has been a power cut until she tries to boil the kettle or use the oven🤣

    I was concerned I'd need to do some rewiring of the CU if I ever lost the inverter so I added two 25 amp single module changeover switches that switch between grid and inverter. I've the main changeover in place too.

    20241202_192115.jpg


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  • Registered Users, Registered Users 2 Posts: 8 SolarBananas


    That sounds great but wouldn't you need to feed the inverter (and the backup output) with the same size cable as your mains?



  • Registered Users, Registered Users 2 Posts: 2,646 ✭✭✭SD_DRACULA


    They are both 16sq so yeah.

    I think there is an easier way to do it with just one cable instead of two, and then you use the changeover switch at the inverter where you change between grid port/eps port



  • Moderators, Home & Garden Moderators Posts: 7,102 Mod ✭✭✭✭graememk


    The cable from the inverter just has to be sized and Protected(MCB size) accordingly. Doesnt have to be the same size as the main tails.



  • Registered Users, Registered Users 2 Posts: 2,646 ✭✭✭SD_DRACULA


    100% - go with what it says in the inverter manual, mine said 16sq but it will be different depending on the inverter power.



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