Im on my NVQ, I have testing questions.

[danspark12345]

Testing questions

I installed a socket outside (on a garden bar) which is run from a DB from the side building, fed from the main CU in the house on a 20amp.

The DB which feeds the garden bar has been turned into a TT system.

1. Would you do EFLi at the DB or main CU?

2. The 3core SWA is only connected to the MET in the CU, this is correct if im right in believing, incase anything was to happen to the SWA between the CU and DB?

3. The DB had 2x MCB and Main switch, so when doing the RCD test, it would be done at the CU in the house on the RCD which feeds the side building DB?

I hope my diagram helps my poor explanation.

Any help appreciated!

 

[westward10]

Although you have created a TT system at the side building ADS must be confirmed up to the point of isolation where it becomes TT. Then imagine two separate systems where your TT essentially has it's own Ze with it's own earth fault loop path.

 

[danspark12345]

Although you have created a TT system at the side building ADS must be confirmed up to the point of isolation where it becomes TT. Then imagine two separate systems where your TT essentially has it's own Ze with it's own earth fault loop path.View attachment 119052

Thank you so much for that!

When I went to do the Ze at the DB, I tripped the RCD in the CU in the house, I understand that's a hard question when there's alot at play, but does anything come to mind?

Also, my Zs at the new socket install was over 200 ohms, what do you do in this situation?

Use RCD as additional and fault?
Can that RCD, be within the socket? If the DB doesn't have an RCD, or would the RCD that feeds it from the CU in the house be sufficient. And then on that, if the DB doesn't have RCD, would you do the RCD test at the CU in the house?

Again, any help truly appreciated