And... is it possible to convert these old boards to DIN-Rail? Also as mentioned - its a flat roof house so not easy to reroute wiring.  Had to remove the ceiling the last time work was done on the DB.

Thanks Eugene,

 

Now this opens another discussion - attached is a picture of my DB - bear in mind this is a very old house - (35 years).  Is the MCB where the City Power feed comes in not an E/L.  It has that test button.

 

The one with the test button is a 3 phase E/L unit.

And... is it possible to convert these old boards to DIN-Rail? Also as mentioned - its a flat roof house so not easy to reroute wiring.  Had to remove the ceiling the last time work was done on the DB.

 

I'm not sure about din rail, but quite possibly. You do get Heinemann adaptor plates which you use with the CBI MCBs (13mm breakers).  You can actually see them in the top rail next to the CBI MCBs and it looks like one is installed next to the E/L unit as well.

The one with the test button is a 3 phase E/L unit.

So is my E/L and CB on the Inverter DB the right way around?  From your thread it seems they should the other way around or doesn't it matter?

I'm not sure about din rail, but quite possibly. You do get Heinemann adaptor plates which you use with the CBI MCBs (13mm breakers).  You can actually see them in the top rail next to the CBI MCBs and it looks like one is installed next to the E/L unit as well.

 Yeah , because currently that 3 phase breaker and the two at the top are hanging loos and being kept in place by the wiring pretty much.  Not good I assume...

So is my E/L and CB on the Inverter DB the right way around?  From your thread it seems they should the other way around or doesn't it matter?

 

I would prefer having the breaker first and then the E/L, but it should not really make any difference.

 

Inverter OUT - breaker - E/L

 Yeah , because currently that 3 phase breaker and the two at the top are hanging loos and being kept in place by the wiring pretty much.  Not good I assume...

 

The way they "clip" into the adapter plate is a bit iffy and they do sometimes "fall out".

THANK YOU for all the guidance - will help a lot to give the to the electrician as I am sure it may help a bit with the install price if planning has already been done - what do you think - was thinking if I did this leg work I might get a bit better price...  But in any event at least I have a MUCH better understanding of how the inverter connects to a DB.  I am assuming single phase would be the same - you would just create two seperate circuits with two seperate neutrals.

 

Attached is the final final version.

Just a couple of comments and questions:

 

1) If the Input and Output Neutrals to the inverter are not connected together within the inverter then I assume you would have to earth the output Neutral of the inverter before the bypass switch? This is to ensure an earth leakage return path while the inverter supplies the load.

 

2) Is it not better to switch over both the Live and Neutral Inverter Input and Outputs with one switching operation? Will try and post a drawing

Just a couple of comments and questions:

 

1) If the Input and Output Neutrals to the inverter are not connected together within the inverter then I assume you would have to earth the output Neutral of the inverter before the bypass switch? This is to ensure an earth leakage return path while the inverter supplies the load.

 

2) Is it not better to switch over both the Live and Neutral Inverter Input and Outputs with one switching operation? Will try and post a drawing

 

Thanks Carl, drawings would be awsome!!

Just a couple of comments and questions:

 

1) If the Input and Output Neutrals to the inverter are not connected together within the inverter then I assume you would have to earth the output Neutral of the inverter before the bypass switch? This is to ensure an earth leakage return path while the inverter supplies the load.

 

Yes.

This is the Bypass box that I used. 

 

It consists of a 3 way switch as follows: 

 

Position "I" - Inverter Bypassed

Position "Off" - switches I & II in open position

Position "II" - Inverter Energized

Just a couple of comments and questions:

 

1) If the Input and Output Neutrals to the inverter are not connected together within the inverter then I assume you would have to earth the output Neutral of the inverter before the bypass switch? This is to ensure an earth leakage return path while the inverter supplies the load.

 

What you'll have to do is to connect the inverter input before the existing ELR and then you have to link the inverter output neutral to earth before the new / second ELR. Any fault currents in the circuits connected to the inverter will trip the new / second ELR and any fault currents in the existing circuits will trip the original ELR. You'll have to connect the input to the inverter before the original ELR, because if you link the inverter output neutral to earth and utility power is available, the original ELR will trip.

I see in your diagram that you pick the utility power for the change-over switch from after the isolator. The drawback is that if you need to work on the inverter and switch off the isolator, your circuits will be dead. If you pick the utility power from before the isolator, they can have power even if you work on the inverter.

 

Another thing I did differently was to make the earth-neutral connection closer to the inverter output, so that if you are in bypass mode, that connection is not in circuit anymore and then you depend on the main earth-neutral connection. It seems a little closer to the spirit of the SANS 10142-1.

 

 

7.12.3.1.3 Where alternative supplies are installed remotely from the
installation, or from one another, and where it is not possible to make use of a
single neutral bar which is earthed, the neutral of each unit shall be earthed
at the unit and these points shall be bonded to the consumer's earth terminal
(see 6.12.4). The supply from each unit which supplies the installation or part
of the installation, shall be switched by means of a switch that breaks all live
conductors operating substantially together (see annex S), to disconnect the
earthed neutral point from the installation neutral when the alternative supply
is not connected (see also 6.1.6).                             Amdt 1; amdt 6
 

Great drawing SuperDIY, but fully agree with jhay comments.

 

Not all inverters have the same setup though so the above neutral earthing solution is inverter specific.

 

Some inverters have the input and output neutrals connected together and then it would not be necessary to earth the neutral on the inverter output. Also some inverters have built in earth leakage protection.

I see in your diagram that you pick the utility power for the change-over switch from after the isolator. The drawback is that if you need to work on the inverter and switch off the isolator, your circuits will be dead. If you pick the utility power from before the isolator, they can have power even if you work on the inverter.

 

Yes, I understand your reasoning. The idea of my diagram is for a sub DB and inverter some distance from the main DB and in that case you have to have a "main switch" on the sub DB (typical SP+N). If you want to supply power to your (inverter) load via the changeover switch in "utility" position, but also isolate the inverter, I would suggest to add another dedicated isolator for the inverter or use a changeover switch with more contacts as per Carl's suggestion/diagram.

 

Another thing I did differently was to make the earth-neutral connection closer to the inverter output, so that if you are in bypass mode, that connection is not in circuit anymore and then you depend on the main earth-neutral connection. It seems a little closer to the spirit of the SANS 10142-1.

 

Agreed.

Not all inverters have the same setup though so the above neutral earthing solution is inverter specific.

 

Some inverters have the input and output neutrals connected together and then it would not be necessary to earth the neutral on the inverter output. Also some inverters have built in earth leakage protection.

 

Agreed. If the inverter then has built-in E/L protection, you don't have to do all of this. If input and output neutrals are connected inside the inverter you can either connect earth and neutral or leave it un-connected.

OK, as per jhay's suggestion, the earth-neutral link is moved closer to the inverter and in bypass (utility) mode it would be out of the circuit. I've also moved the optional "Inv. Out" breaker to also be out of the circuit when the changeover switch is in bypass (utility) position and I've added a separate isolator feeding the inverter input.