Rewiring a 5-Bedroom House with Powerwall 3 Integration

[Writer]

Hi everyone,
I’m working on a full rewire for a 5-bedroom house with a loft, first floor, and ground floor, along with an attached garage. Renovation is currently underway, and i’ve been instructed to install two consumer units (CUs):

First CU in the loft to serve the loft and first floor.
Second CU for the ground floor, garden, and garage.

All cabling has been installed according to regulations, except for the main supply cable. The homeowner is installing a Powerwall 3 solar system, which they say will not feed back to the grid. However, they want essential loads separated from non-essential loads on both floors.

My Questions:

1. To properly separate essential and non-essential loads, would I need two separate consumer units on each floor (one for essential and one for non-essential loads)?


2. Would this setup require two separate mains cables—one from the grid and one from the inverter—to feed the consumer units?


3. Since the main supply cable will be routed under floorboards, does it have to be SWA, or are there alternative compliant options?

I’d really appreciate any detailed guidance on this. Thanks in advance!

 

[buzzlightyear]

1. To properly separate essential and non-essential loads, would I need two separate consumer units on each floor (one for essential and one for non-essential loads)?


2. Would this setup require two separate mains cables—one from the grid and one from the inverter—to feed the consumer units?


3. Since the main supply cable will be routed under floorboards, does it have to be SWA, or are there alternative compliant options?

1) It depends what you call non essentials .
2) the inverter cable goes to one consumer unit main .
3) regading the cable run to another sub cable under floors no protect
but in walls then rcd protection .

 

[Writer]

1) It depends what you call non essentials .
2) the inverter cable goes to one consumer unit main .
3) regading the cable run to another sub cable under floors no protect
but in walls then rcd protection .

Thanks for your response mate: the non essential loads are the cookers and heating appliances. All sockets and lighting are to be on the solar. I only have the space under the floor board to run the mains cables feeding the CUs, can I use tails inside enclosed in trucking or 2 swa cables 16mm each. One for the non essential loads CU and the other coming from inverter to the other CU. Thanks

 

[buzzlightyear]

the non essential loads are the cookers and heating appliances. All sockets and lighting are to be on the solar. I only have the space under the floor board to run the mains cables feeding the CUs, can I use tails inside enclosed in trucking or 2 swa cables 16mm each. One for the non essential loads CU and the other coming from inverter to the other CU

who requested the two consumer units .

 

[Writer]

who requested the two consumer units .

The Tesla powerwall 3 configuration the owner sent to me . And I don’t know if there another way to separate the load with 2 CUs. Split load CU won’t work as there is 2 are 2 powers feeding each floor. Solar and grid for different loads

 

[Writer]

The Tesla powerwall 3 configuration the owner sent to me . And I don’t know if there another way to separate the load with 2 CUs. Split load CU won’t work as there is 2 are 2 powers feeding each floor. Solar and grid for different loads

I meant without 2 CU

 

[buzzlightyear]

The Tesla powerwall 3 configuration the owner sent to me . And I don’t know if there another way to separate the load with 2 CUs. Split load CU won’t work as there is 2 are 2 powers feeding each floor. Solar and grid for different loads

who has designed this .

 

[Writer]

I don’t know but let me share the configuration sent me maybe that will be clear

 

[Writer]

I don’t know but let me share the configuration sent me maybe that will be clear

I don’t know but let me share the configuration sent me maybe that will be clear

 

[buzzlightyear]

looking at the spec then the wiring diagram there two ways to wiring it
regarding non essential or essential,me where the cables from the solar to the main back up gate way,putting one cu for essential and one non essential near each other with out putting a sub main cables up.
but its up to you how you wiring it,design wise .

 

[Writer]

looking at the spec then the wiring diagram there two ways to wiring it
regarding non essential or essential,me where the cables from the solar to the main back up gate way,putting one cu for essential and one non essential near each other with out putting a sub main cables up.
but its up to you how you wiring it,design wise .

Yes, that is what I understood from the diagram. So my concern is that I will have 4 CUs in total. 2 on each floor.
First floor cus will have cable from solar on one unit and cable from the grid on the other one. Same thing on the ground floor. Is that right?

 

[buzzlightyear]

Yes, that is what I understood from the diagram. So my concern is that I will have 4 CUs in total. 2 on each floor.

Why are there 4 cu in total.

 

[Writer]

He house has loft, and first floor on a different CU and the ground floor and garage plus garden on another CU . This is before solar configuration came in place. This was how the house wiring was done. Then I was sent that diagram I showed you for the solar .

 

[buzzlightyear]

It says on the wiring diagram showing
2 consumer units not 4,the only way is either have it says on the daigarm or put more solor on the roof.

 

[Writer]

It says on the wiring diagram showing
2 consumer units not 4,the only way is either have it says on the daigarm or put more solor on the roof.

The diagram was given after the whole installation has been done. Which already we have 2 CUs, one for the first floor and other one for the ground and garage. But being powered by the main cables from the meter. Now they want to install solar and need some of the loads in each floor to be on solar and rest on the existing CU. Doesn’t that makes sense why the need for 2 more CUs?

 

[buzzlightyear]

Either configuration of the whole installation for two more cu. I would explain to the customer. It can not be done.

 

[snowhead]

You will need to know from whoever is installing the Powerwall where they are locating the both the Powerwall unit and Backup Gateway(s), essentially just a changeover relay / contactor and whether they can manage with 1 Gateway or they need 2.
That'll determine how to run the cables to each C.U., you can't plan anything without knowing that.

Split load CU's should work

 

[Writer]

Either configuration of the whole installation for two more cu. I would explain to the customer. It can not be done.

Then it will require to have the whole house CU on the ground floor while I wire the cables from the first floor and loft down to it

 

[Writer]

You will need to know from whoever is installing the Powerwall where they are locating the both the Powerwall unit and Backup Gateway(s), essentially just a changeover relay / contactor and whether they can manage with 1 Gateway or they need 2.
That'll determine how to run the cables to each C.U., you can't plan anything without knowing that.

Split load CU's should work

The gateway needed is 1 as per the diagram . They want non backup
Board and backup board separately on each floor which is why it sums up to 4 Cus. Also split load won’t work as I can’t have 2 mains connected into it . One of the solar and other of the grid