Ring Final Circuit

[kendo57]

Any ideas? Getting 0.49 ohms on L to L and N to N end to end test, and 0.30 ohms on CPC to CPC end to end, tightened all connections on sockets. 2.5 csa on live conductors, 1.5 csa on CPC.

 

[Fleeting]

Are there any parallel paths caused by boilers, water heaters etc...
Is is contained in steel conduit.
Supplentary bonding connected.

 

[Murdoch]

Not unusual to see such readings

 

[kendo57]

Are there any parallel paths caused by boilers, water heaters etc...
Is is contained in steel conduit.
Supplentary bonding connected.

No parallel paths, conduit, or supplementary bonding. Static caravan, been doing them for years, CPC reading always been 1.67 times reading of line conductors.

 

[Sharpend]

Have you dropped all socket fronts? You may have a spur off to underneath/outside that is bolted to the chassis?

 

[kendo57]

Have you dropped all socket fronts? You may have a spur off to underneath/outside that is bolted to the chassis?

Yeah, no spurs.

 

[Sharpend]

Are the back boxes fixed to anything metal?

 

[SPECIAL LOCATION]

How big is the caravan? is it the 0.30 or the 0.49 that appears more realistic with respect to the probably cable lengths used?

i.e. 0.49 of 2.5mm is around 66m
and 0.30 of 1.5 is around 25m

If this is just a static caravan it wouldn't take too long to open all sockets split the ring at the CU, then go along checking each section as if it were a radial to see where about the readings become inconsistent...

Also double checking cable sizes are correct throughout as you test each outlet?

e.g. LN&E all connected on one leg of the ring LN&E all open on the other..
Measuring L->E and L->N at every socket and see if calculated cable lengths from you readings look feasible?

Could you have some damaged squashed cable somewhere?

 

[poni]

i.e. 0.49 of 2.5mm is around 66m
and 0.30 of 1.5 is around 25m

I would go to the mid point and check for a fault or short ,it looks like its half way along your ring , or remove all CPC from the board and test it again, then if you have the same reading test to all other CPC's to see if you have crossed them over

 

[kendo57]

No, and don't forget the ring cpc's are disconnected from the met when carrying out an end to end test

I would go to the mid point and check for a fault or short ,it looks like its half way along your ring , or remove all CPC from the board and test it again, then if you have the same reading test to all other CPC's to see if you have crossed them over

Thanks for the pointers, really appreciated.

 

[binky]

No, and don't forget the ring cpc's are disconnected from the met when carrying out an end to end test

Thanks for the pointers, really appreciated.

Any damp in the walls? I chased a similar issue for hours many years ago, to cut a long story short, the new plaster was thick and still damp under the dry skin

 

[Fleeting]

Aside from separating the cpcs at the board make another break in the circuit and see if you lose continuity.

 

[kerching]

Probably asked before but have you done an '8' test on L&E