High Zs value with 2 sockets

[TheCodboy]

Hi all, Doing some pre board change testing and ive found 2 sockets with high Zs readings. Everything else is fine, done all my end to ends and the Zs's are what should be expected. A couple of the sockets have Zs lower than expected but 2 are higher. They should be about 0.8 ohms but ive got one at 1.20 and one at 1.40. Taken the highest value socket off, re terminated, still high. Tested at the terminals of the socket just in case the socket was duff, but still high. Its a PME system with a good low ZE (0.15). Any thoughts people??

 

[Pete999]

how many cables was at this socket ? you posted you had done end to end at consumer unit (assumed) what about r1 + r2

You mean R1+R2? and OP what was r1, r2,and rn?

 

[TheCodboy]

Delete.

You mean R1+R2? and OP what was r1, r2,and rn?

L=0.92 N=0.92 E=1.83
Measured Ze 0.14

 

[Midwest]

Do you see the point about doing r1, rn, r2 at the sockets with higher Zs result?

 

[TheCodboy]

Do you see the point about doing r1, rn, r2 at the sockets with higher Zs result?

If i take it at the sockets, they should obviously be the same as at the board,hence confirming a ring. So if they are different, interconnection maybe?

 

[westward10]

From your readings it will not be the same as at the board, they may well be open circuit.

 

[Midwest]

If you do end to ends at these sockets with a higher Zs reading, and you don't get continuity, then this socket will more likely to be a spurred socket. Importance of doing dead tests in the correct order. Although understand what you were trying to achieve, pre CU change.

Edit, as suggested by the other chaps!

 

[TheCodboy]

From your readings it will not be the same as at the board, they may well be open circuit.

I think a return to the property on monday and get some socket fronts off....

 

[Midwest]

I think a return to the property on monday and get some socket fronts off....

Think, as the chaps have been saying, your higher Zs readings are because the sockets have been spurred. Easy assumption to make when you see two cables at a socket. (See my post #8).

 

[Midwest]

Think, as the chaps have been saying, your higher Zs readings are because the sockets have been spurred. Easy assumption to make when you see two cables at a socket. (See my post #8).

Least I hope it is, anything else might be more stressful

 

[TheCodboy]

Least I hope it is, anything else might be more stressful

Me too!!!!

 

[ChrisElectrical88]

L=0.92 N=0.92 E=1.83
Measured Ze 0.14

These reading are too high for a RFC to be below 100m

 

[Midwest]

These reading are too high for a RFC to be below 100m

My CG 2392 course workbook suggests circuit length of 45-50m circuit length (2.5 + 1.5mm), then there's the old dodgy socket connections?

 

[ChrisElectrical88]

0.92/7.41 x1000

124m

Also the CPC is greater than 1.67x the r1 and rn which would suggest a loose connection on that somewhere

 

[westward10]

Or 1.0 cpcs.

 

[ChrisElectrical88]

Don't know the 1.0mm resistance off my head (1.5 is 12.41) I'm sure if someone could do that calculation and get close to 124 then it would confirm that.