Ze on a TT at marina

[Harvey]

The Ze is over 250 ohms on a TT so unstable, you can not TN-CS it so it says in the regs (709.553.14) .It is gravel land Is it a case for deeper earth rod (all covered by 30mA rcd)?

 

[Zeespark]

Deeper earth rod and I would say a 100mA RCD (I could be wrong on both counts though). The BGB will have guidance on this.

AndyGuinness

 

[sparkytim]

200 ohms is only a recommended value to endeavor to achieve (MAY be unstable)

See BGB pG 57 411.5.3 NOTE 2

The REQUIREMENT is to meet Ra x I delta n < 50V

 

[SPECIAL LOCATION]

Is this the actual supply to the boats..

or to building near the marina..?

The buildings can be TNCS.. 709.411.4 pg 226

RCDs 709.531.2 pg 227 refers to 415.1.1 pg 66

requires 30ma & 40ms @

 

[Harvey]

Building next to a marina and sockets next to the water not for boats

 

[Evans Electric]

Mug up on Marinas in the Regs if I were you Harvey.

 

[AC Alan]

Building next to a marina and sockets next to the water not for boats

This was the section B scenario on one of the 2391 exams last year.

If it is an actual install you need a longer rod as said above to reduce your Ra reading (Ze).

 

[Harvey]

I have mugged up if you read correctly

---------- Post Auto-Merged at 20:53 ---------- Previous post was made at 20:50 ----------

Thanks AC alan