House db

[Johandup]

Is it necessary to rewire your db to seperate high load feeds from the low ones?

This is when using a Mecer inverter.

The main purpose for this installation is to be independant of the municipality when there are power failures.  

How else do you prevent overloads from the high loads in your household?

[pilotfish]

Yes it is advisable to do so, every installation is different but this is my suggestion for an average home;

Keep oven, hob, geysers, aircons, underfloor heating etc directly on grid or use gas/solar as energy source where possible - put lights (all LED or CFL) and selected plugs on the inverter.

The more panel power, inverter capacity and battery capacity you have the more you can shift off grid section of the DB and onto the Inverter section. With 1 Axpert I would stick to lights, TV, computers, fridges, and maybe the pool pump if you have sufficient panel power.

[___]

I recall vaguely there is a general rule of keeping your backup circuits and other circuits separate. It doesn't necessarily mean they have to be in separate physical DBs, but there has to be a clear gap. Physically it is a lot easier, because there are requirements for separate neutral bars (for example) too, so it really makes a lot of sense to have a sort of "grid to the left, ups to the right" (♬ here I am stuck in the middle with an Axpert ♫...).

Something that makes a lot of sense is a tall DB with two rows. Then you can have a clear split as well.

There are also requirements for clear labeling, where that sub-db is fed from. That becomes significantly harder to do when they are all in the same box.

[pilotfish]

Something like this...

[ibiza]

2 hours ago, plonkster said:

I recall vaguely there is a general rule of keeping your backup circuits and other circuits separate. It doesn't necessarily mean they have to be in separate physical DBs, but there has to be a clear gap. Physically it is a lot easier, because there are requirements for separate neutral bars (for example) too, so it really makes a lot of sense to have a sort of "grid to the left, ups to the right" (♬ here I am stuck in the middle with an Axpert ♫...).

Something that makes a lot of sense is a tall DB with two rows. Then you can have a clear split as well.

There are also requirements for clear labeling, where that sub-db is fed from. That becomes significantly harder to do when they are all in the same box.

[GVC]

Thanks for bringing up this topic Johan.

I was contemplating the same thing after hearing the inverter beeping while drawing too much current from the grid / inverter.

Though i must say this has made the missus and myself more wary before running the oven, dishwasher and kettle at the same time....lol

I am going to split my db as suggested by the guys and have also ordered a modular change over switch from acdc express.

 

[___]

1 hour ago, pilotfish said:

Something like this...

 

This is mine. I have the grid circuits (which in my case is most of them) at the bottom, in the original hole in the wall. Then I have the middle row dealing with the inverter input, so that contains the anti-islanding and general power-monitoring unit and its breaker, this drives the contactor in that box to the left. The inverter output goes to the top row, and that has my lights and the plugs circuit that I want backed up.

My inverter is a real hybrid, so surplus power can be pushed to the other circuits.... which is why the top board is so sparsely populated. Also, that Ziehl unit takes a LOT of space :-)

 

[Barezzi]

This has been an area of concern for me, as the grid is very unstable where I reside. So I can't enjoy the benefit quoted. 

An ATS to switch the heavy loads on/off based on the battery SOC during the day sounds like something that should work. 

On 26/10/2017 at 11:18 AM, plonkster said:

My inverter is a real hybrid, so surplus power can be pushed to the other circuits....

 

[pilotfish]

26 minutes ago, Barezzi said:

An ATS to switch the heavy loads on/off based on the battery SOC during the day sounds like something that should work. 

This would be easy to do using the Victron BMV-702 which has a relay that will switch based on various settable parameters - SOC being one of them. The relay would control a contactor (rather than ATS which may not be the right piece of kit in this instance) with the equipment to be controlled all connected to the correctly rated contactor.

[Barezzi]

Can the contactor switch the heavy loads to inverter during the day when the grid fails as long as the soc is within set limits? 

[pilotfish]

Yes it can but I misunderstood your requirement - initially you said on/off now you are talking about changeover from grid to inverter. This can be done using two separate 4 pol contactors if the load is 3 phase (one normally open and the other normally closed) or a single 4 pole contactor that has 2x N/O contacts and 2x N/C contacts if your load is single phase. The switching would still be initiated by the BMV-702.

Your local electrician should be able to assist you with this.

[PaulF007]

On 10/26/2017 at 11:22 AM, GVC said:

I am going to split my db as suggested by the guys and have also ordered a modular change over switch from acdc express.

@GVC  Just be careful what you get from ACDC . The quality of the last change over I got from them was not as good as one would expect. I you are going to Middelburg have a look at Tools and Things (Just across the road from the mall). But be prepared if you have never been there as that is one M**RSE shop. Got my last CB's (SWAN) from then for about R 25 each. The changeover was a bit more but still good value.