Testing of new consumer unit install - Help needed please

[pencilpusher]

I am changing my consumer unit from a 16th edition to a 17th edition one.

I have a question about testing the new CU and its certification. All circuits will be additionally protected by RCD's or RCBO's except a distribution circuit to my detached garage. This is run from the CU in SWA for about 4 meters to the garage 2 way CU and is then protected by an RCD in the garage. I presume this is OK otherwise I would have the circuit protected by an RCD at source and then protected again in the garage with another RCD and I will struggle to achieve discrimination??

My question relates to the EIC for the new CU. What tests need to be done on the SWA out to the garage CU. It will be protected by a 16amp CB at source. Is R1+R2 done on the SWA leading to the garage CU? How about ZS and how is that measured and from where? My thinking is that the ZS for this circuit will be Ze + (R1+R2) of the cable from the CU to the garage CU but before connection to another circuit??

This is for my part P assessment but this is causing me a bit of confusion.

I am fine with the testing of all circuits fed from the new CU except this distributiion one. Any advice would be gratefully received.

Thanks

PP :juggle:

 

[diditrain]

No your zs for the distribution circuit/armoured is done at the garage d/b and is referred to as Zdb.
You only have one Ze and that will be at your main intake position

 

[pencilpusher]

No your zs for the distribution circuit/armoured is done at the garage d/b and is referred to as Zdb.
You only have one Ze and that will be at your main intake position

Sorry, that is what I meant. Ze (at origin) +(R1+R2) for the swa to garage. That will be ZS??

How is that shown on the EIC for the outgoing garage circuit

Thanks

 

[SirKit Breaker]

The Cu for the house will be the MAIN CONSUMER UNIT, the circuit running from it to the garage CU will be a distribution circuit, and this CU will be GARAGE.

You will have 2 sets of Electrical Installation certs, test results, and inspections, one for each CU nad its associated circuits.

So house CU you are OK with. The Garage CU supply cable is the cable from house to garage, the protective device is the mcb in house CU suppling the garage CU, so what you need to do is treat the house as one installation and the garage as another if you get my drift.

Cheers............Howard

 

[pencilpusher]

Howard, thanks very much. It must be my explanation of this that's the problem even though I have tried to make it simple!

The CU in the garage will not change. It already exists. I will not be touching it. My problem is with the new CU one in the house which has a 16amp CB protecting the cable from the house CU to the garage, I am not sure of the tests required for the house EIC columns for the db circuit to garage. I would like to check on what tests I need to show on the house CU EIC for this outgoing circuit please.

Thanks for your patience on this!!

PP:blush5:

 

[topquark]

Don't forget to check if your bonding needs to be upgraded as well (poss OK if the wiring was done to 16th ed as well as the old CU).

 

[diditrain]

On your house EIC just record all of the tests you would normally carry out for any other circuit. It is just a circuit supplied from your main C/U

 

[pencilpusher]

Bonding is fine. Thanks for responding.

 

[diditrain]

Your Zs for your distribution circuit taken at the garage consumer unit is then recorded on your garage schedule of test results as your Zdb. It is also recorded on your house schedule of test results in the Zs column