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049derek avatar image
049derek asked

Essential and non-essential loads on the same household plug circuit

Hi. With a Multiplus II I understand that I can have essential loads on AC-1 out and non-essential on AC-2 out. And to make this useful the DB board needs to be split - no problem so far. But what if I have essential and non-essential loads on the same plug circuit in the house? eg I have internet, a printer etc on a plug circuit, but on the same circuit we sometimes switch on an air conditioner, or maybe plug in an iron to iron clothes. It could also be a heater.
So when on batteries I guess this would overload the system which would then trip. That is expected and people would need to have discipline. But what happens when mains comes back? Does the inverter still trip on overload according to its power spec? Or does it switch the power through and no longer monitor the overload (because it is not the inverter producing the power). Or (maybe this is crazy) can you connect AC-1 out and AC-2 out to the same load? This way one would expect it to trip if too much is plugged in while on battery, but it shouldn't trip when it switches back to mains. Please help

Multiplus-II
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2 Answers
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wkirby answered ·

Never ever whatsoever should you ever connect AC-OUT1 and AC-OUT2 together - ever.
They are presented as two separate outputs for the reason that they should be kept separate and feed separate DB boards and thus separate circuits.

You should never ever, ever, whatever you do never ever connect those two outputs together, never ever. Even if it is the only thing you never do. Please don't do it.

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sharpener answered ·

When the grid is available the Multi will allow power to all loads up to the maximum pass-through rating (50A or 11.5kW for the 5kVA version). So little risk of tripping in a typical small-ish house.

Connecting the AC1 and AC2 Out together will not work as you describe and may cause damage. This cross-connection would also mean that all other loads are connected to both outputs as well!

As you know, AC2 Out will have no voltage on it when there is no grid power. So you could wire a relay/contactor to that and use it to switch on specific loads or specific sockets on your AC1 circuit only when AC2 is powered, which may achieve your objective. (Depending on your setup you may have Aux relays already which can be used with Assistants, but AFAIK they are not capable of carrying substantial load currents anyway.)

You could use a 12V power brick and 12V relays to allow you to safely run the control wiring using bell wire. Alternatively you may be able to do the same using wireless control modules e.g this or this or other home automation products, which would obviate the need for changing the fixed wiring at all.

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